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1. Manufacturing Conditions and Procedures
This manual covers general requirements and procedures for the manufacture of cement mill with respect to the following items
1. item
1) Quality of steel materials and castings
2) Procuring conditions for steel materials
3) Manufacturing conditions and procedure for welded structures
4) Accuracy standards for parts (see the following references)
- Reference 1 : Ordinary Tolerances for Machined Dimensions
- Reference 2 : Tolerances for welded Structures
5) Non-destructive Examinations
- Reference 3 : Non-destructive Examination standard for Major Components of Cement Mill
2. Detailed Manufacturing Conditions and Procedure
1) Quality of steel materials and castings and forgings
The following standards shall be complied with as regards the steel materials and castings to be used for the cement mill
a) Steel plates and pipes
Symbol Code Applicable standard
SSP JIS G3101 Rolled steel plates for general structures, class 2
SM41 A,B JIS G3106 Rolled steel plates for welded structures, class 1
SGP JIS G3452 Carbon steel pipe for piping
STPT38 JIS G3456 Carbon steel pipes for high-temperature piping, class 2
SSA(L) JIS G3101 Rolled steel plates for general structures class 2 Angles
SSB JIS G3101 Rolled steel plates for general structures class 2 Bars
SF45 JIS G3201 Carbon steel forgings
2) Procurement conditions for steel materials
- Steel plate for mill shell
a) The width and length of steel plates shall have repair cutting allowances to prevent lateral bending and out-of-squareness of cut plate
b) Manhole reinforcing materials shall be of such size as including allowance for edge bending when they are pressed or bent
c) Materials shall be free of defect such as inclusion of mill scale.
d) SM41B shall be Charpy tested, more than 2.8kg-m at 0℃ by Charpy method.
e) Each steel plate for the shell shall be ultrasonically tested by the steel manufacturer to ensure freedom of defect. The ultrasonic test shall comply with JIS G080 “Ultrasonic Examination of Pressure Vessel Steel Plate”. The place to be tested shall be BL
- Mill shell flange materials
a) The raw mill shell flanges shall be made of three pieces of square bar. The square bars shall be hot bent and welded into a ring. The size of the square bar is shown in the attached dwg. Torsion of square bar shall not be greater than 20mm.
b) The square bars shall be ultrasonically inspected to ensure freedom of defect.
3) Manufacturing Conditions and Procedure for welded structures
a) Welding shall be carried out according to the general welding procedure.
See the reference 2 “Acceptance Standard for Welded Structures”
b) Parts to be machined later shall be welded after fit-up and assuring that they have sufficient thickness and machining allowance.
c) Carry out welding, observing the following instructions
i) Preheating temperature of thick plates before welding :
- Plates 50mm thick or over : To be preheated to a temperature higher than 100℃
- Plates thinner than 50mm : To be preheated to a temperature higher than 50℃
ii) Use low-hydrogen electrodes after drying them at 350℃ for one hour
d) Welded parts shall be straightened and tempered properly before being machined.
e) Welded shall be annealed, if necessary, as follow
REFERENCE 1
ORDINARY TOLERANCES FOR MACHINED DIMENSION
1. Scope
If no dimensional tolerances (figures or symbols) are specified for machined parts of cement mill in the drawings, the following tolerances shall be applicable.
2. Dimensional Tolerances
1. Disposal of Reject
IF any part has a dimension exceeding the tolerance, the personnel concerned shall agree upon whether such part should be used with or without repair or discarded, taking into account its destination.
REFERENCE 2
ACCEPTANCE STANDARD FOR WELDING STRUCTURES
1. Scope
This standard covers the acceptance criteria for the visual, dimensional and shape inspections of the welded structures for cement mill. If, however, any other tolerances are specification, such shall be observed.
2. Inspection Items
1) Visual inspection
2) Dimensional inspection
a. Product Length
b. Foundation bolt hole pitch and connection bolt hole pitch
c. Dimensions of welding grooves
d. Leg length
e. Plate thickness after machining
3) Shaper inspection
a. Squareness
b. Straightness
3. Allowable Limits for Visual Inspection
1) For allowable limits for welds, see table 1.
1) The surface of welded structures shall be free of excessive spatter, constraining jig marks, rusting and damage
2) Gas-Cut surfaces shall be smooth and clean
1. Tolerances for Dimensional Inspection
1. Disposal of Reject
If any part is rejected by inspection, the personnel concerned shall agree upon whether such part should be used with or without repair or discarded, taking into account its destination.
REFERENCE 3
NON-DESTRUNTIVE EXAMINATION STANDARD FOR MAJOR COMPONENTS OF CEMENT MILL
1. Scope
This standard specifies the non-destructive examination procedures and acceptance criteria for the major components of the cement mill.
Major Mill Components :
1) Trunnion
2) Mill Shell
2. Magnetic Particle Inspection
The magnetic particle inspection shall be carried out according to the following procedure.
1) Method
(1) Each component to be examined shall be magnetized continuously by the prod or yoke method and inspected in two directions at right angles to each other.
(2) Dry or wet magnetic particles shall be used.
2) Conditions
(1) The magnetizing current shall be DC 100-125 amperes/25mm for the prod method and not less than AC2500 ampere turns for the yoke method.
(2) The distance between the prods shall be 50 to 300mm.
(3) The properties of magnetic particles to be used(Susceptibility, dispersibility, suspendability and color) shall be suitable for the material, surface condition and expected defect of a component to be examined.
3. Ultrasonic Inspection
The ultrasonic inspection shall be carried out according to the following procedure.
1) Method
(1) In principle, welds shall be inspected by the angle beam technique. The other areas shall be inspected by the normal beam technique.
(2) Conditions
- Pulse echo ultrasonic testing apparatus shall be used.
- Frequency shall be 1 to 4MHz.
- When the normal beam technique is used, the sensitivity shall be F1 =75% + 2dB using STB-G, V15-4. When the angle beam technique is used, the sensitivity shall be as specified in JIS Z3060.
(3) Dry or wet magnetic particles shall be used.
4. Inspection Time : To be informed later
5. Location
In principle, the locations in Table 4 shall be inspected. Further details shall be agreed upon after award of the contract.
6. Acceptance Criteria
Defects shall be accepted or rejected according to the criteria in Item 8. Unacceptable defects shall be removed and repaired according to the procedure approved by HANJUNG
7. Acceptance Criteria for Defects in Welds
Tables 8 and 9 show the welds to be inspected and acceptance criteria for the defects
Table 8. Welds to be inspected
Describe the capacities of the machines and equipment to be used for manufacturing cement mill components.
1. Crane
Lifting Capacity x quantity
Name of manufacturer
2. Lather
Workable diameter x length
Name of manufacturer
3. Vertical lathe
Workable diameter x height
Name of manufacturer
4. Drilling Machine
Working Diameter x height
Name of manufacture
5. Bending roller
Bending plate thickness x bending diameter x bending width
Name of manufacturer
Limit to weight
6. Press
Bendable plate thickness x bending width
Name of manufacturer
7. Casting equipment
Name of manufacturer
Melting capacity
Experience of casting special materials
Capacity
Fuel
Width x height x length x capacity (ton)
8. Other equipment
Describe any other specifications which may represent the capacity of equipment. Describe what measures you will take if any of the machines in your factory does not have a capacity required to manufacturer the inquired cement mill component(s).
1. Mill Body Manufacture
1. Mill Tube
1.1
Normally, more than 4 plate sections must not be used for manufacture of the mill tube. A deviation herefrom shall be approved by HANJUNG.
The welded seams must be placed so that they are at lest 100mm from bolt holes and manholes welded seams must be ground plain on the inside.
Circular seams must be placed so that they are at least 100mm from any imaginable bolt row which can be placed on the mill tube when the distance between the bolt rows corresponds to the smallest division unit which is 250mm. See mill tube drawing.
Longitudinal seams should be placed so that they are not in continuation of seams on adjoining plate sections.
1.2
Stamping of boiler plates shall be in accordance with the workshop certificates. When the plates are marked off, it may be necessary to move the stamp to an easily visible place on the mill tube.
1.3
Diagonal measuring. Check that the finished plates are rectangular. It can be done by checking whether the opposite sides are equally long and the diagonal measurements are identical.
1.4
Bevels for welded joints must be made with a mechanically propelled flame cutter or by edge planing or turning. Beveling which is not shown on the drawing must be made in accordance with the welding method.
1.5
Rolling. Plates must be rolled without sharp bends and faces. Rolling must not be done at a plate temperature below +5℃.
1.6
Cutting of manholes and outlet opening must be done after circular rolling of plate sections.
Manholes must be on the lines M-M and N-N (see mill tube drawing). When the position of the manholes have been fixed, mark M-M and N-N lines with a centre punch inside the plate section.
The Center punch marks must reach from the plate edge and approx. 50mm
Bender the marking more visible by application or a painted white strip 50mm wide.
Prior to cutting of manholes, examine the planned points on the plate for lamination by subjecting them to supersonic testing. (In the case of ascertained lamination, contact HANJUGN)
The holes are to be cut with a template guided automatic cutter (e.q. ESAB type STAR)
Drill a hole approx. 10mm wide through the plate to start cutting. The hole must be drilled at the center of one of the long sides of the manholes, slightly towards the center of the manhole as shown in Fig 1.
Fig 1.
Cutting must be stared and finished in the drilled holes, and the remaining plate tip must be chiseled and ground away.
The cutout must lie so far within the final line work can be ground away.
Weld repairs must not take place
The Plate edge of the hole must be given a curvature with 4mm radius on both sides of the plate, as shown in Fig 2.
Fig 2
After grinding and polishing of the hole edges they must be examined carefully by means of magnetic particle inspection must also be removed by grinding and polishing.
1.7
Welding :
All circular and longitudinal seams are to be made by means of submerged arc welding, unless otherwise arranged with HANJUNG head office.
When the carbon equivalent of the material is higher than 0.41%, preheating must be made in accordance with the standard in force for the actual plate thickness. For calculations of carbon equivalent, see material sheet “ Unalloyed steel weldability”
The bevels for welds between mill heads and mill tube as well as welds at the transition from one plate thickness to another, are shown on the drawing.
Only welders who have passed a work test based on recognized regulations applying to boiler welding may be employed. See Danish Standard DS320.1 and/or INSTA 20 (Inter Nordic Standardization) or a corresponding international standard.
Besides the welds shown in drawing and instruction materials, welding and repair welding must not be carried out without the written consent of HANJUNG
1.8
Manufacturing Tolerances
1.8.1
During the manufacture of the mill tube, the following tolerances of the finished mill tube must be taken into account :
A) Deviation of every single bolt hole from theoretically correct position -------- +/-2 mm
B) Circumference measure of mill tube (πx D) ---------------------------------------- +/-10 mm
-0 mm
C) Length L of mill tube ----------------------------------------------------------------------- +/-5 mm
-0 mm
D) Stagger of Plates inside tube ----------------------------------------------------------- max. 1 mm
E) Mill tube ovality --------------------------------------------------------------------------- +/-10 mm
F) Diameter reduction (“stays”) ----------------------------------------------------------- max. 3mm
G) Rectilinearly measured with piano wire -------------------------------------------- max. 3mm
1.8.2
The stagger “D” is checked with a straight edge and a curvature template before and after welding. Length of straight edge and template : 1m.
Regard must be paid to :
Tube Concumference.
Real plate thicknesses.
Alignment of plate edges.
1.8.3
Because of the tolerance (E) for the ovality of the finished mill tube, the single plate sections must be checked for ovality before they are welded to the other plate sections.
This check is carried out by drawing two diagrams in each section while they stand with the mill axis vertical. Sharp bends resulting from rolling and welding must not have cambers of arch larger than 1.5mm as measured with a template.(Length of template 1m)
For drawing of diagrams, see section 15.
The diagrams must be handed over to the HANJUNG Inspector.
Plate sections with the seam circumference measure must be welded together in other that the stagger of the plates (D) does not exceed 1mm.
1.8.4
Continue the inside marking of lines M-M and Non the outer side of the mill tube and mark the lines in the same way as inside the tube.
1. MILL HEAD FOR WELDING-ON
2.1
Turn off the heads (03) and (04) to final dimensions, with the exception of the plane faces of contact for the trunnions. Allow 5-6mm of material to remain on these faces of contact for subsequent turning.
2.2
Mark off center lines M-M and N-N on the outer side of the mill heads. Make the marking clear by means of a painted white stripe 50mm wide.
2.3
Mark off and complete all holes in the mill heads, apart from the holes for tight-fitting bolts.
2.4
Pre-drill the holes for tight-fitting bolts through a jig to 6mm below final size. (Hole diameter A in Fig 3, sub-section 8.2.1)
Countersink and chamfer the holes from the rear.
Subject to the unavailability of a jig for the mill head, pre-drill the holes through the trunnion. See sub-section 4.1
2. TRUNNIONS
Trunnions are made to separate workshop instructions.
3.1
Pre-drill the trunnion holes for tight-fitting bolts (07) through a jig to 6mm below final size.(Hole diameter B in Fig 3, sub-section 8.2.1)
The holes can be drilled simultaneously with drilling the corresponding holes in the mill head. See sub-section 3.4
3.2
Mark off the center lines M-M and N-N on the drilled flanges of the trunnion the jig. Make the marking visible by means of a pointed white stripe 50mm wide
3.3
Mark off, finish-drill, and remove burrs from all holes in the trunnions, except the holes for tight-fitting bolts facing the head
3.4
Finish-drill the holes for the tight-fitting bolts between outlet trunnion (02) and transition piece (06) through a jig. Drill and ream the holes to final size.
Match-mark the flanges, and mark off M-M and N-N lines with a white stripe 50mm wide before the flanges are taken apart. Remove burrs from all bolt holes.
3. WELDING ON OF MILL HEAD
4.1
The carrying plate for outlet head and distance rings together with any diaphragms must be placed in the mill tube before the heads are welded on, unless otherwise stipulated in order or parts list
Note : All parts in mill heads and trunnions must be trial-mounted before the head are mounded.
4.2
The mill heads must be mounted on the mill tube so that the M-M lines on tube so that the M-M lines on tube and heads are flush. A method of assembly must be used which does not require welded-on retainer irons.
4.3
Welding bevels are often aligned by the use of erection irons, after which the seams are to be tack-welded. Next, weld together mill heads and mill tube. If – quite exceptionally – the erection irons are welded on instead of being bolted on, such welding must be done s far inside the mill tube as possible
In no circumstances should erection irons be welded to the heads.
4.4
Undercuts should not be allowed to develop during welding, and the height of projections outside and inside the mill tube must be in compliance with the demands set forth on drawing and instructions.
4.5
All traces of welded-on erection irons, etc., must be removed completely by grinding. Subject the ground areas to a magnetic particle examination incorporating an electromagnet. All visible faults found during this test must also be removed by grinding and polishing.
Welded repairs must not be made
4. INSPECTION OF WELDED SEAMS
5.1
The loading of a mill body is different for the different welded seams, and so different quality demands are also made on the seams.
Demands on the individual welded seams :
5.1.1
Longitudinal seams (Submerged arc weld). Seam class B to general workshop instructions;
However, with the following deviations :
Test Method : Ultrasonic test
Convexity, internal : plain
Stagger of plates : max. 1mm
5.2
Longitudinal Seams (Electroslag weld)
Seam class B to general workshop instructions
However, with the following deviations :
Test method : Ultrasonic or X-ray test
Convexity, internal : Plain
Stagger of plates : max. 1mm
5.3
Circular Seams at Mill Heads
Seam class C to general workshop instructions
However, with the following deviations :
Test method : Ultrasonic test
Convexity, Inside and Out : Plain
Stagger of plates / Mill head : max. 1mm
5.4
Circular Seams, others
Seam class B to general workshop instructions
However, with the following deviations :
Test method : Ultrasonic test
Convexity, Internal : Plain
Stagger of plates : max. 1mm
5.5
Stress-Relieving Annealing
Stress-relieving annealing is, normally, not carried out unless a special arrangement to this effect has been made with HANJUNG
5. TURNING OF MILL BODIES WITH WELDED-ON HEADS
6.1
Clamp the mill body in a lathe by means of special center pieces. See example of center pieces and roller bearing centers on sketches II and III.
6.2
Check the external roundness of the mill tube.
For ovality tolerance, see subsection 2.8.1
Drawings for a roundness gauge designed for this special purpose, can be obtained from HANJUNG.
Diagrams of ovality measurement must be handed over to the HANJUNG inspector.
6.3
Finish-turning of the contact faces of both heads for trunnions must be made in the same setup.
If the mill body has a flange for gear rim, it must also be turned off in the same setup.
Maximum surface roughness : R = 5my
The rectangularity of the contact faces to the mill axis must be tested with a straight edge placed across the opening in the mill head.
Maximum permissible deviation measured with a feeler gauge = 0.05mm
6.4
If a sufficiently large lathe is not available, it will be necessary to discuss the method of machining the mill head contact faces with HANJUNG.
6. MOUNTING OF TRUNNIONS
7.1
Bolting : Bolt trunnions and mill heads together smaller than the predrilled hole diameters. Center lines M-M and N-N must coincide in trunnions and mill heads.
Check flanged joints with a 0.05 mm feeler gauge.
If the mill head bores have expanded because of deformations caused by welding together with the mill tube, the radial clearance between mill head and trunnion must be distributed evenly.
7.2
Drilling of holes for tight-fitting bolts and insertion of tight-fitting bolts.
Since considerable deformation may occur in mill heads (03) and (04) during welding to the mill tube (05), the procedure described in the following must be following for tight-fitting bolt joints between mill head and trunnion.
7.2.1
In order to prevent trunnion and mill head being offset relative to each other during drilling ad reaming, one hole must be completed first and the tight-fitting bolt be driven in and tightened. Then the diametrically opposed hole is to be completed, and the tight-fitting bolt is driven in in and tightened. All the other holes for tight-fitting bolts can then be drilled and reamed. Gradually as the holes are completed, the tight-fitting bolts are driven in, but only if the mill is to be shipped with the trunnions bolted on.
Fig.3
The procedure for completion of the single holes is as follows (Fig. 3) :
a) Bore the predrilled hole to a size of 2mm smaller than its final dimension.(Holes diameter C).
b) Use a counterbore to bore the hole to a size of 0.5mm smaller than its final dimension. (Hole diameter E)
c) Use a machine reamer to ream the hole to its final size. (Hole diameter E).
d) Spot-face the contact faces (F) and (G) for the tight-fitting bolt head in the mill head and for the nut on the trunnion. It is a conditions that the chamfer has been made during pre-drilling of the mill head. If not, the operation must be carried out now.
Always check the size of chamfering relative to indication on drawing. (Normally 3mm x 45℃)
It is a fundamental requirement that the tolerance on drawing in terms of perpendicularity between hole for tight-fitting bolt and the contact face is adhered to ( 0.05mm)
e) Drive home the tight-fitting bolt and tighten the nut to torque specified in the parts list.
The bolt must be driven home (test for sound), since otherwise it may work loose during operation.
7.2.2
Note : if for some reason it should become necessary to use tight-fitting bolts of a larger diameter than stated on the drawing, the bolt head diameter (and hence the countersink for the head in the mill head) must be made correspondingly larger. In the case of such a change must be sent to HANJUNG head office immediately, for both calculation and spare parts reasons.
1. OTHER TYPES OF MILL BODY
8.1
The Preceding sections only describe the manufacture of mill bodies with welded-on heads. Section 8 deals with other common types of mill body – to the extent to which their manufacture deviates from the manufacture already described
8.2
Mill body with flange for bolted-on slide ring(s) and drying compartment, flange for gear rim, and welded-on mill head at outlet.
Fig.8
The following procedure may be used for the manufacture.
8.2.1
The mill tube is manufactured in accordance with the drawings, as mentioned in section 2.
8.2.2
Make flanges for mill tube, drying compartment, and gear rim in accordance with the drawing. After turning 5-6mm material must be left on all contact faces for subsequent machining.
8.2.3
Place the mill tube on roller supports and position head and flanges on the mill tube so that the parts are at right angles to the mill axis.
Check that the M-N marking of the parts coincides with that of the mill tube.
Fix the parts in the correct position, if necessary by the use of erection irons and tack-welding.
Notes : Erection irons must not be welded to the mill head, but only to the mill tube. See sections 5 and 6.
A basic electrode(mat.720) must be used for welding on such erection irons.
The same rules as mentioned in section 5 shall apply to removal of erection irons.
8.2.4
The finish-welded mill tube must be turned on a horizontal lathe. Turn off the mill head contact face for the trunnion, the mill flange contact face for the slide ring, and if necessary the contact faces of the gear rim flange for the gear rim in the same setup so that these faces become parallel.
Mark off the pitch circle for the gear rim bolt holes. Measure inwards from the finish-turned outer diameter of the flange and mark the pitch circle with the turning tool.
8.2.5
Place the mill tube on the roller support again. Mark off the line M-N on the mill tube flange and pre-drill all holes and holes for tight-fitting bolts through a jig. For positioning of jig, see sketch VII.
Place the predrilled slide ring on the mill tube flange.
Check the contact between ring and mill flange with a 0.05mm feeler gauge.
See that the M-N marking on slide ring and mill tube coincides.
Drill and ream the holes for tight-fitting holes together in the following way :
a) Finish on hole as described in sub-section 6.2.1 and drive in the tight-fitting bolt.
Use gauge block for tightening if necessary.
b) Finish the hole diametrically opposed to the first hole and drive in the tight-fitting bolt.
c) Carry out the same operation at two holes offset through 90°relative to the first holes so that a total of four tight-fitting bolts have been inserted before the remaining holes are finish-drilled and reamed.
Dismount the slide ring and bore the predrilled holes for non-tight-fitting bolts.
8.2.6
The drying compartment is to be manufactured on the same lines as apply to the mill tube, and the welded-on flange to be turned off so that its contact face is at right angles to the axis of the drying compartment. Carry out M-N marking of drying compartment and flange.
Pre-drill all holes and holes for tight-fitting bolts through a jig.
Place the drying compartment in the vertical position with the slide ring flange at the top and place the slide ring on the flange.
Check the contact between slide ring and drying compartment coincide.
Drill and ream the tight-fitting bolt holts in the same way as described in sub-section 8.2.5.
Separate slide ring and drying compartment and bore the remaining holes for non-tight-fitting bolts in the flange in accordance with the drawing.
8.2.7
For mounting of trunnion, see section 8.
8.2.8
If the mill body is to be shipped with a bolted-on trunnon, slide ring, and drying compartment, all tight-fitting bolts must be tightened at the specified torque.
For Transport of mill tube with slide ring but without drying compartment, it will suffice to use only tight-fitting bolts with gauge block as shown at joint B in Fig 9.
Fig.9
8.3
Mill body with welded-in slide ring and flanges for bolted-on mill head / Trunnion and gear rim.
Fig 10
The following procedure can be used for the manufacture ;
8.3.1
The mill tube is manufactured in accordance with the drawing, as described in section 2. Flanges for gear rim and mill head are made and welded on as described in sub-sections 8.2.3.
8.3.2
Place the slide ring in position on the mill tube so that its M-N marking coincides with that of the mill tube and its axis has the same center as the mill axis.
Fix the slide ring in the correct position by means of erection irons. If exceptionally the erection irons have to be welded on, basic electrodes must be used. Welding must not be done on the slide ring. See also sub-section 1.7 and section 4 and 5.
8.3.3
Place the finish-welded mill body on a horizontal lathe and carry out alignment and turning of flanges and slide ring.
All contact faces of both flanges and slide ring must be turned off in one setup. The faces are shown on the mill tube drawing.
Polish the outer surface of the slide ring with emery cloth and oil. Level of acceptance for the slide ring surface is the same as for trunnions outside range 02. See separate instructions for mill trunnions.
8.3.4
The bolted-on mill head / Trunnion can be mounted in the following way :
a) Pre-drill the finish-turned mill head / trunnion and the mill tube flange through the same jig or templates
b) Mount mil head / Trunnion on mill tube so that the M-N marking is correct, and so that the axis of the mill head / trunnion centers with that of the mill
Check the mutual contact of the two parts with a 0.05mm feeler gauge.
c) Ream the holes for tight-fitting bolts together in mill head / trunnion and mill flange in the normal way way and drive in the tight-fitting bolts if the mill body is to be shipped with the mill head / trunnion bolted on. If the mill head / Trunnion are to be dismounted, burrs must be removed from the holes.
If a jig / template is not available, the following alternative method can be used :
a) Mount mill head / trunnion on mill tube. Remember that erection irons must not be welded to head or trunnion.
See that mill head / Trunnion and mill tube are centered. Check marking as well as the mutual contact of the parts. (0.05mm feeler gauge).
b) Align a drilling machine so that the drill is perpendicular to the flange of mill head / Trunnion.
c) Pre-drill one of the holes for tight-fitting bolts.
d) Bore the hole to a size which is 2mm below final size.
e) Use a counterbore for boring to 0.5mm below final size.
f) Finish-ream the hole with a machine reamer and drive in the tight-fitting bolt.
Note : Items 3, 4, 5 and 6 must be carried out without any change in the drilling machine and mill tube positions.
g) When the first tight-fitting bolt has been inserted, the diametrically opposed bolt is mounted in the same way and then 90°.offset – two bolts which are also diametrically opposed. Next, the remaining holes are finished.
h) If the mill body is not to be shipped with the mill head / trunnion bolted, dismount these parts and remove burrs from holes.
8.4
Mill body with peripheral outlet, welded-on mill head as well as bolted-on slide ring and flange for gear rim.
Fig 11
8.4
Mill body with peripheral outlet, welded-on mill head as well as bolted-on slide ring and flange
It will be most expedient to cut out the outlet openings for peripheral outlets in the heavy plate section with a mechanically propelled flame cutter to a size which is 5-6mm smaller than the final size, and then finish the holes in a milling machine.
If milling facilities are not available, the method for manholes as described in-sub-section 1.6 can be used. The drawing specifications in regard to the degree of machining of hole edges and radii of curvature must be observed closely.
8.4.2
Manufacture and welding-on of mill flange, outlet flange, and flange for gear rim as well as flanges for peripheral outlet are carried out as described in sub-section 8-2 and in accordance with drawings.
8.4.3
To turn the finish-welded mill body, all the contact faces on mill head, mill flange, gear rim flanges for peripheral outlets must be made in the same setup.
8.5
Mill body with two welded-in slide rings and, if required, drying compartment / tube for scooping device, and bolted-on outlet.
Fig 12
For mill bodies of this type with too large dimensions or own weight to be set up in a lathe in one piece, the following method can be used :
8.5.1
Manufacture the mill tube in two sections :
Inlet end /.and outlet end.
8.5.2
Weld together drying compartment / tube for scooping device, slide ring, and mill tube inlet end on the lines laid down in sub-section 8.3.2
Weld the mill tube outlet end to the associated slide ring in the same way.
8.5.3
Turn off these two parts of the mill body after welding / so that slide rings, bevels, and contact faces for inlet and outlet and outlet respectively are turned off in the same setup. Beveling of the tube ends must be as shown on the mill tube drawing.
The slide rings must be polished with emery cloth and oil. The acceptance level for surface faults is as described in sub-section 8.3.3
8.5.4
Place the mill body parts on roller supports and carry out careful alignment and bolting together before the parts are welded together.
After welding together, all turned faces must coincide without untrueness and eccentricity.
8.5.5
Where the mill tube can be set up in a lathe in one piece, our normal rules for welding bevels must be followed, see sub-section 1.4
2. INSPECTION AND DOCUMENTATION
HANJUNG’s supervisory inspector is to have access to inspect the mill sections at any reasonable time during manufacture. Examples of inspection form to be completed by the supplier, are inserted as enclosures in the present instructions.
3. PAINTING AND RUST-PROOFING
Normally, a mill body is treated as described in the following. However, special customer requirements are often made. If this is so, it will be stated in the order or in a special letter.
10.1
Before Painting :
Clean the surface of grease, rust, etc., both inside and out to preparation degree st.2.
10.2
Outside of mill body :
Like painting Program No.3
Mill body inside, incl. Diaphragms, supporting plate at outside head, etc., :
Like painting program No. 1
Take care that M-M and N-N marking do not disappear during painting, Sub-section 13.1
10.3
All machined surfaces : Apply a rust-proofing material
4. PACKING OF TRUNNIONS
Packing of trunnions must be carried out according to the packing drawing which is always stated in the parts list. The drawing contains instructions both for packing of trunnions to be shipped bolted to the mill and for trunnions to be shipped separately.
When trunnions are to be shipped separately, the machined contract faces on both mill heads and trunnions must be protected by a bolted-on wooden cover.
5. SHIPMENT
12.1
When the mill body is to be shipped with the trunnions bolted on, the nuts of the tight-fitting bolts must be tightened at the prescribed torque.
12.2
If the trunnions are to be shipped separately, they must be dismounted, and burrs be removed from the holes for tight-fitting bolts in mill heads and trunnions.
12.3
Any supports and transport mountings as well as lifting tackle must be bolted on. In no circumstances must welding be done on the finished mill body.
Strapping for the mill body must be placed on the tube, not on the trunnions.
6. MARKING AND FIRM NAME
See Sketch VI
The mill body must be marked on the lines laid down on the sketch. All lines, letters, and figures to be in white paint and of the dimensions specified.
Face of type : HELVETICA or Similar face
a) HANJUNG monogram no. 10 (21) (for detailed dimensions, see drawing . To be painted through a template.
b) Mill body order No. (22) (example). The order No. used in this example is stated in the parts list.
c) Parcel No. (23) (example). The parcel No. used in this example is stated in the instructions from our shipping department.
d) Firm name and registered address of the HANJUNG office concerned (24) (example), exactly as specified. As far as possible, Place the firm name in the center of the mill body, or as close to the center as possible.
e) The weight of the mill body in kg(25) (example).
f) Center lines M-M and N-N are marked in a white line 50mm wide, painted inside in the entire length of the mill body as well as on the outer side of the mill heads.
The Mill body must also be marked with address according to shipping instructions.
If the mill body is shipped with trunnions dismounted, their packings must be marked in the same way as the mill body.
Machinery parts must in no case bear the name of the manufacture
1. ROUNDNESS GAUGE
The mill tube deviation from circularity is determined by the use of a roundness gauge designed as shown on sketches IV and V
The disc with the tracing paper, sketch IV, Fig 4 and 5, is fitted at right angles to the tube axis, as shown, and is aligned in such a way that the guide pin in the center of the diagram paper is as close to the tube center as possible.
The special-type trammels are placed on the guide pin, and while the free end (see sketch V, Figs 6 and 7) is pressed against the inner wall of the tube and is move along the circumference from and the center – traces a diagram.
The diagram represents the circumference of the tube on a considerably reduced scale, but shows the variations of the tube radius on a full scale.
It is important that the diagram should be market at once for orientation in the circular direction as well as for showing from which end the tube is seen, in view of comparison of the same tube, and so that it can form the basis for alignment of the tube.
The free end of the trammels is to be moved round on a level exactly at right angles to the tube axis, since otherwise the diagram will become distorted.
When the ovality or roundness of a tube is required to be e.q. max. +/-10mm, it means that the curve must lie within two concentric circles with diameters D+10 and D-10mm, as shown in the diagram, sketch IV, Fig 5.
Tube sections which are placed in the horizontal position without stiffening will be more or less deformed by their proper weight. Deformations due to proper weight can be determined by comparison of two diagrams traced before and after respectively the tube is turned through 90°(Preferably on transparent paper).
2. DOCUMENTATION FOR HANJUNG HEAD OFFICE
1. Form U-1251
Ovality measurement on lathe
2. Form U-1151
Inspection from
3. Supersonic test report with sketches for examination of welded seams.
4. X-ray films of electroslag-welded seams
5. Repair reports and weld statistics.
6. Diagrams of Ovality measurements of the single plate sections before welding together.
7. Certificates and documents mentioned in section 1 of the instructions.
1. KEY TO SKETCH AND FIGURES
01 Trunnion, inlet
02 Trunnion, outlet
03 Mill head, inlet
04 Mill head, outlet
05 Mill tube
06 Transition piece
07 Tight-fitting plate
08 Lathe face plate
09 8 centering screws for alignment of mill body after setup
(to be checked with dial micrometer (17))
10 Inner inlet center piece (standard, can be used for all mill sizes)
11 Outer inlet center piece (special for every mill size)
12 Outer outlet center piece (special for every mill size)
13 Inner outlet center piece (special for every mill size)
14 8 centering screws for alignment of mill body after setup
(to be checked with dial micrometer (17))
15 Roller bearing center
16 3 screws for fixing of bearing during setup
(to be slackened before mill body is turned)
17 Dial micrometer
18 Contact faces for trunnions to be turned in same setup.
21 HANJUNG monogram
22 HANJUNG order no.
23 Parcel No.
24 Firm name and registered address
25 Weight of mill body
26 M-M and N-N lines
27 Drying compartment
28 Slide ring
29 Mill flange
30 Gauge block
31 Tight-fitting bolt
1. Welded-Up Slide Ring
1. General
A slide ring, welded-up of web plate (01) and ring (02), forms an integral part of the mill body when, after finish-welding and rough-turning, it is welded to the mill tube and the mill transition piece. See Fig.1
Finish-turning of the slide ring takes place after the ring has been welded to the mill body. The finish-welding and welding to the mill body is dealt with in instructions manual .
The manufacturer is free to choose whether to make the slide ring with or without an allowance for machining on the web plate and on the inside of the ring. See sub-sections 3.1 and 3.2.
Production methods, including welding procedure, must be selected with regard to meeting the requirements stated in the instructions manual and on the drawing. Deviations from the requirements must be approved by HANJUNG in writing.
2. Material
2.1 Welding
Filler metal, such as electrodes, wire, welding powder, etc. must be selected with regard to giving the finished weld a tensile and ductile strength equal to that of the parent material. See sub-sections 2.2 and 2.3
1.2 Ring(Cylindrical part)
The ring is to be made from normalized boiler plate corresponding to HANJUNG mat.120. Further the plate must be of z-quality i.e. have physical properties in direction of thickness, e.g. corresponding to :
JIS G 3103(z25)
DIN HI 17155 Z3
NF-A-36-202-Z25
BS 23B (Hyzed 25)
One of the characteristics of these qualities is a contraction rate of min. 25% during tensile testing in the direction of thickness. Z-plates are made by a number of steel works as plates with a low content of sulfur and phosphorus.
1.2.1 Ultrasonic Testing
All plate for the ring must be subjected to ultrasonic testing before rolling.
The tests comprise a 100% surface test in a zone, at least 200mm wide, where the web plate is to be welded to the ring, and a 100% test in the rim zone.
The result must at least meet the requirements of class 3 in “Stahl-Eisen Lieferbedingungen Nr. 072-77” with respect to surface tests as well as rim zone tests.
The requirements are cited in the tables on the next page.
Ultrasonic Surface Testing of Heavy Plate | ||
Probe : Type SE 4 MHz, 24 mm dia. | ||
The test is to be made along a square grid side at least 200mm. See Drawing. | ||
Max. permissible size of areas in which the echo from defects is larger than the bottom echo. | Permissible number of defects per ㎡ | |
Locally | All over the plate | |
1000 ㎟ | No more than 10 per ㎡ | No more than 5 per ㎡ |
Ultrasonic Rim Zone Testing of Heavy Plate | ||
Probe : Type SE 4 MHz, 24 mm dia. | ||
A complete test is to be made in a rim zone as wide as the thickness of the plate, but not less than 50mm. For un-machined plate : Not than 80mm | ||
Max. permissible size of areas in which the echo from defects is larger than the bottom echo. | Permissible length of echos from defects. | Permissible number of areas with defects per meter rim zon |
1000 ㎟ | Max. 40 mm | Max. 3 areas. |
1.2 Web plate (plane part)
The web plate is to be made from normalized boiler plate corresponding to HANJUNG mat.120
1. Manufacture
Clamping irons etc. should as far as possible be placed where any crack, deriving from welding on of the irons, will be removed by the subsequent machining. Alternatively the welding should include a local pre-heating.
The heat source used in connection with pre-heating, welding and heat treatment must not create risks of decarbonization of the component.
3.1 Web plate (plane part)
If difficulties in connection with meeting the roundness tolerance may be foreseen, the ring must be given an allowance for machining on the inside that allows machining to the inside diameter stated on the drawing.
Rolling /Bending of plates may not take place at plate temperatures lower than 5℃.
Pre-bend the outer plate ends in a press, or roll the plate with an extra length, so that the plate after rolling and adaptation has a pure, cylindrical surface all the way to the plate ends.
When ring and web plate are welded together, variations in the cross sections to be welded may cause deformation of the ring. To avoid this, the ring must, when finish-rolled, be without flat surfaces or sharp bends.
Check the roundness of the ring during rolling by means of a template covering about 45℃ of the circumference.
HANJUNG recommends electroslag-welding for the longitudinal seams of the ring. If other methods are used, the beveling of the plate edges must be adapted to the chosen method.
The welding must be done by certified welders only.
Their certificate must be valid for comparable welding work with regard to
- quality requirements
- plate thickness
- material
- procedure (manual or automatic)
Refer to one of the following standards :
- DS 322 Certificering af svejsere.
- BS 4871 Parts 1. Approval of welders
- DIN 8560 Prufung von Stahlschweissern.
- ASME IX Welding and Brazing Qualifications.
The plate must be pre-heated according to BS 5135 which stipulates the temperature in relation to the carbon equivalent of the material, the electrodes used, etc.
The carbon equivalent is calculated from the following formula ;
CE = C + Mn / 6 +(Cr + Mo +V) / 5 +(Ni +Cu) / 15
If the ring has been made without allowance for machining on the inside, all traces of any welded on clamping irons, etc. must be removed by grinding. A magnetic particle test must be made on the ground areas. All defects revealed by the test must be removed by grinding and polishing.
The inner welding seams must be ground flush with the surface.
.3.2 Web Plate
If difficulties, may be foreseen with regard to staying within the planeness tolerance without machining, the web plate may be manufactured with an allowance for machining to the dimensions stated on the drawing.
Welding and inspection of the radial seams of the web plate must follow the instructions given for welding of the ring. See-Section 3.1.
If the web plate has been made without allowance for machining, the welds must be ground flush with the surface.
The outer diameter of the web plate should be machined either in a lathe or in a boring mill, but not until the ring has been completed and its dimensions checked, in order to obtain the smallest possible clearance for the welding between the web plate and the ring.
Important
A proper fit between web plate and ring is a pre-condition for obtaining an ideal welding operation with a minimum of stress concentration and deformation.
1.3 Inspection
Before assembling web plate and ring, the two components should be inspected as follows.
3.3.1 Inspection of the welded seams
The finished seams must meet the requirements of quality QC. Refer General Workshop Instructions.
Method of inspection : 100% ultrasonic testing.
The qualifications of the ultrasonic test operator must correspond to ASNT-TC-1A, level.1
3.3.2 Dimensions control
The roundness and the inside diameter of the ring must be checked in order to establish the outer diameter of the web plate. See sub-section 3.2.
The roundness may be checked by means of diagram tracer. See section 10.
If the diagram shows deviations from the theoretically correct circular form, larger than stated on the drawing, the roundness should be improved. Either by heating along one or more of the generatrices of the ring, or by re-rolling.
2. ASSEMBLING THE WEB PLATE AND THE RING
4.1 Assembly
The turned web plate is to be placed in the annular part in such a way that the clearance, and consequently the cross section of the weld, will be as uniform as possible on the entire circumference.
4.2 Welding
In order to meet the requirements of the drawing with regard to perpendicularity, planeness etc. the welding sequence must be such, that the symmetry of the component is maintained throughout the welding operation. This may be obtained by following the procedure shown on Fig.2, where welding is done alternately from the two sides of the slide ring.
Important :
Preheating must be applied during the entire welding operation, including the tact welding. The preheating temperature must correspond to BS 5235 (See sub-section 3.1), but never be lower than 75℃
Preheating and maintaining the temperature during the welding operation must be done without decarbonizing the parts.
When the first run is finished on side A (Marked (1) on Fig.2), the slide ring is turned over, and the root of the first run is cleaned by grinding or by turning.
The cleaned groove is to be checked 100% by magnetic particle test. Any local defects must be removed by grinding. The root of the weld must, before the welding operation is continued, be absolutely free from defects.
3. STRESS RELIEF ANNEALING
The finish-welded slide ring is to be stress-relief annealed in a furnace. The heat source must not cause any risk of decarbonization of the component.
Both web plate and ring should, during their entire stay in the furnace, be fitted with thermo sensors connected to a curve recorder.
The web plate should be supported around the center opening.
The stress-relief annealing should be done according to the following specifications :
a) Heating rate : Temperature increased evenly at a rate of 75℃/h
b) Stress-relief Temperature
: 600±25℃
c) Duration : One hour per 25mm max. thickness of plate
d) Cooling rate : Cooling along with the furnace
but at a maximum rate 50℃/h
e) : The slide ring must remain in the furnace until
the temperature is below 100℃. If transported
out of doors, the slide ring should be covered.
f) : Cooling to room temperature must take place in
static air, under roofing, and with the slide ring
placed upon a support with room temperature.
If it proves necessary to make weld repairs after the slide ring has been stress-relief annealed and checked acc. to section 6, the heat treatment must be repeated.
Acceptance of the heat treatment procedure will be based upon the heat treatment report.
4. CHECKING THE WELD BETWEEN RING AND WEB PLATE
When repair welds (if any) and subsequent stress-relief annealing has been completed, the weld must be examined to ascertain that it meets the requirements of quality QC, acc. to general workshop.
This examination must not take place until at least 48 hours after the stress-relief annealing.
Checking Procedure
a) 100% Magnetoflux test (MT) on the weld, from both sides (A and B) of the slide ring.
b) 100% Ultrasonic test (UT) as follows
Check from both sides of the web plate with angle probes.
Check from the outside of the ring for laminar tearing and junction defects with a standard probe.
Check from the outside of the ring for transverse cracks with angle probes.
c) 100% dimension check(DT) on both sides after finish-machining of the weld. See section 7.
5. MACHINING
7.1 Rough-turning
a) Rough-turning the outside profile of the slide ring in such a manner that a suitable allowance for machining is left for a finish-turning to final dimensions after the slide ring has been welded to mill tube and transition piece.
b) Finish-turn the weld beveling and, if relevant, the thickness of the web plate and the inside diameter of the ring.
c) Finish-turn the inner bore diameter and the recess for tools. See drawing.
d) If the slide ring has been made without allowance for machining on the inner ring diameter and on the web plate, the two circular welds between annular part and web plate are to be finished-machined, until the radius and surface finish stated on the drawing have been obtained. If the welds are turned, the machining must not penetrate to the ring part or the web plate. Sharp transitions must be smoothed out by grinding.
e) Examine the welds for cracks by means of a magnetoflux test. The welds must, after machining, meet the requirements of quality QC.
1.2 Finish-Machining
Important !
The remaining finish-turning of the slide ring is not to take place till after the slide ring has been welded to the mill body. See instruction manual.
6. INSPECTION AND DOCUMENTATION
The HANJUNG inspector must at any time have access to inspect the parts during their manufacture and to check any relevant documentation.
The complete documentation comprises :
a) Works certificates for all plate material.(sub-section 2.1 and 2.2)
b) Report on ultrasonic testing of plates for the annular part
(sub-section 2.2.1)
c) Report on Ultrasonic testing of longitudinal seams of the ring and the radial seams of the web plate.(Sub-section 3.3.1)
d) Report on Ultrasonic and Magnetoflux tests of weld between ring and web plate. (sections 6 and 7)
e) Complete dimension sketch of finished component.
f) Report on repair work
g) Report on heat treatment.
7. PAINTING AND CORROSION PROOFING
If the slide ring to be shipped separately, the finish-machined surfaces must be corrosion proofed according to General Workshop Instructions.
If the slide ring is welded to the mill tube immediately after manufacture, painting and corrosion proofing must be done according to instructions.
8. DIAGRAM TRACER
The deviation of the ring from true circular form may be checked by means of a diagram tracer as shown on enclosures I and II.
The axis of the ring must be vertical.
Place the disc with the tracing paper (see Fig 3) at right angles to the ring and adjust it so that the guide pin in the center of the slide ring as possible.
Place a trammel point on the guide pin. Press the end of the trammel against the inside for the ring, and move it around the entire circumference as shown on Fig 5 and 6. A pencil, placed on the trammel at a suitable place over the paper 9see Fig 3), now draws a diagram on the paper.
It is imperative that the trammel point is moved in a plane exactly perpendicular to the axis of the ring, or the diagram will be distorted.
The diagram shows, in a highly reduced scale, the inside shape of the ring, while the differences measured on the radii are shown in true scale.
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