solidworks sheetmetal 코너 요령

[조용범(운영자)]

1.   Introduction: 

This is a “how-to” which explains the different scenarios for the SolidWorks “closed corner” sheet metal feature.  It explains some of the limitations and situations. Also, some alternatives to the closed corner and work-arounds are suggested.  Essentially a “closed corner” closes the gap in the corner of a sheet metal part. 

 

Open Corner Becomes Closed

2.   Basic Use and Definitions

Closed Corner Types

A sheet metal closed corner can extend one or two corner faces as needed to create three possible corner options:

Type1 – Inner Corner:

Inner Corner to Inner Corner.  In this case, both panels are extended to meet in a common corner.  This might be useful when using a corner weld on the outside and a minimal envelope is needed for the part.

Type2 - Outer Corner:

Full Overlap to outer surface.  In this case, one panel is extended to the outside of the other.

Type3 - Inner Plus Overlap:

 

Extension to inner surface with outer overlap.  In this case, one panel is extended to the inside of the other and the outer one is extended to the outside of the other.  The simple case shown here was modeled with “traditional modeling” to show the third option, which correctly previewed, but would not resolve as previewed using closed corner.  Generally this type of corner is hard to attain with the standard closed corner feature, but can be easily modeled.

See Section 4 below on alternatives and work arounds. 

3.   Conditions / Failure Modes

Required Conditions For Closed Corner:

They only work for 90 degree corners with 90 degree flanges (except with “inward” offsetting). 

These fail:

An exception to the 90 degree rule is when a flange is offset into the part.  Then an “inner to inner (Type1)” closed corner will work, but will only influence the second flange and not trim the first.

This works:

This Does Not:

Use With Edge Flanges

Closed corners are used in conjunction with edge flanges (i.e. not bends that come from the “insert-bends” method).

 

Use With Miters

They work well on external miter flange profiles, but with the corner relief conditions of the miter (typically splined relief).  Also works on internal miter corners, but with the flat blank intersection error that is inherent with miters.

This miter allowed closed corners, but could not unfold one corner:

A “Type1” inside-inside closed corner was substituted for the problem area shown above and the part would then unfold.

Note the splined relief (bend waist) in the formed & flat part as well as the intersection in the flat:

Note: It is very common for the modeler to preview a state of a closed corner which it will not be able to create.  This is the “down side” of using the closed corner.  While it shows the preview, it will often times not create the feature.

Common Failure Modes:

Modeled Pre-Relief

When the given corner has been pre-relieved, or does not originate from a single point.  This is similar to the “excessive offset” problem, but will fail even if the pre-modeled relief is less than the bend radius.  The feature depends on the original edge flanges and relief being taken from an orthogonal point as the meeting point of three planes (bottom and two side flanges)

Flange Sketch “Near Edge” Modified

When a radius or chamfer has been added to the top corner of the edge-flange sketch or the sketch has an interruption in the edge near the corner.

Trim Side Bends = Off

When the “Trim Side Bends” option is off, closed corners will not work. As an added note, “Trim Side Bends” only seems to work for 90 degree corners in any case.

With “Trim Side Bends” Off    

With “Trim Side Bends” On

Flange Sketch Pull Back

When the edge of the face to be extended has been pulled back from the corner (even .001), the closed corner will fail (pulled back or moved away from the corner via dimension).

Sketch Modification On Near Edge

When the Sketch has been notched, only the face directly adjacent to the corner can be extended. (I.e. Extension is not multi region).

Only the bottom edge can be extended in this case.

Perfect Planarity

When “Perfect Planarity” exists between the inner face of an edge-flange and the “extended to” edge-flange, the closed corner cannot reach the far-side.  Try adding a .001 micro-gap offset to the “second” edge-flange feature.

Perfect planarity is when the inner edge flange and the outer flange edges (red) are perfectly co-planar.  This condition limits the ability of the closed corner to reach the outside of the part.  This is a variant of the “zero thickness geometry” limitation in the modeler.

Excessive Offset in “Second” Edge Flange

When the “second” edge flange has been offset too far to the outside, a closed corner is not attainable.  The closed corner will fail when the offset exceeds the inner bend radius of the edge flange.

The green region shows the offset amount.

4.   Alternatives / Work Arounds

Note: Both of these alternatives fail under perfect planarity conditions, as do most sheet metal features.

Traditional Extrude

This method also allows shortened extensions (I.e. Mid-material) and multiple profiles.

The basic method is shown below on a corner with two 80 degree edge flanges.  This works as well with a 90 degree bend or an alternate angle.

The nice part about this method is that it will work for many angles and is more robust when the angles are changed.

First, extrude the end face “Up to Surface”

 

 (Alternate view)

Then, Extrude the second end face “offset from surface” by .001 or whatever makes sense for your given manufacturing process.

For the method above, the desired corner style determines which surfaces to extend to.  For example, if a “type 1” corner is needed, the inside surfaces would be selected instead.

Additionally, this is a great method for closed corners with a “mid-material” requirement (for example, when an outside welded corner bead or tooling clearance is needed).  In this case, “Offset from Surface” can be used and made 1/2 material thickness, or whatever is needed.

 

Edge Flange Sketch Detail

The “sketch method” is probably the most elegant and easy to use.  It simply consists of making the sketch for the second flange have more detail and creating the overlap as the required application. 

Often the required closed corner can be attained by editing only one sketch.   The closed corner may also have interruptions in the panel as shown below, or may be a simple solid panel, as needed.

Additionally a sketch modification can be combined with the “traditional” extrude described above.

 

PDF Version

A printable PDF version of this information is available here.

“Legalese”

All suggestions made here are for training purposes only.

The author is not liable for any loss relating to the misapplication or usage of this information. 

You may freely use, reproduce and print this data as long as it remains intact in its original format.

The information presented here may be used for “paid” training purposes.

[김상철(FS 3015 프로디자인)]

다 영어네.. 해석좀ㅋㅋ

[오재영]

ㅜ.ㅜ 좋은 팁같은데.. 영어네여;; 그림으로나마 잘보고 갑니다~

[한동희]

좋은자료 감사합니다~ ^^

[딸기잼(안양시)]

정보 감사합니다.