CN111069338A

CN111069338A - Convex feature roll punching forming limit evaluation die and measuring method thereof

Info

Publication number: CN111069338A
Application number: CN201911381329.6A
Authority: CN
Inventors: 李大永; 梁振业; 杨浩
Original assignee: Shanghai Jiaotong University
Current assignee: Shanghai Jiaotong University
Priority date: 2019-12-27
Filing date: 2019-12-27
Publication date: 2020-04-28

Abstract

The invention provides a convex feature roll-punching forming limit evaluation die and a measuring method thereof. The upper die set comprises independent die blocks, wherein the recessed upper die block has a recessed feature; the lower die set comprises independent die blocks, wherein the lower lug die block has a raised feature; the recessed features of the upper die block are matched with the raised features of the lower die block to draw material to flow during rotation of the die blocks to form the raised features. The forming limit of the roll-formed raised features of the sheet material is evaluated by forming the raised features with different sizes, measuring the strain of the raised feature areas and the sizes of the raised features, and providing a test basis for establishing a design rule of the roll-formed part.

Description

Convex feature roll punching forming limit evaluation die and measuring method thereof

Technical Field

The invention relates to the field of plate forming, in particular to a convex feature roll punching forming limit evaluation die and a measuring method thereof.

Background

The roll punching process is a composite forming process, and essentially combines a punching process with a roll bending process. The roll punching process is particularly suitable for processing narrow and long variable-section parts, and has the advantages of stable forming process and small redundant deformation of the plate. The raised feature is a common variable cross-section feature that is used for assembly and positioning. Most of the existing studies on the forming limit relate to the forming limit of a stamping process, and patent CN1903474A provides a forming limit testing device relating to a hydraulic bulging forming process. Patent CN2676182Y provides a die for forming test, in particular, relates to a forming limit test of arc or rectangular sample of stamping process. Patent CN2702311Y provides a forming limit diagram measuring mold for a differential thickness laser tailor-welded blank, which can be used to obtain a forming limit diagram of a differential thickness laser tailor-welded blank of a stamping process. Patent CN201780237U provides a die for testing the forming limit of a sheet material, which is added with a heating component, and can complete the forming limit test of isothermal or differential temperature press forming of the sheet material within a certain temperature range.

However, the above measuring apparatus for the forming limit is not directed to the roll press forming process, and a patent related to a forming limit evaluation die of the roll press forming process is proposed at present. Due to the complexity of stress and strain in the forming process of the roll punching forming process, the forming limit obtained by a general test is not suitable for the roll punching process, and the application and popularization of the roll punching forming process are severely restricted by the lack of the forming limit data of the variable cross-section characteristic roll punching. Therefore, it is necessary to develop a forming limit evaluation mold suitable for a roll-punching forming process to obtain a roll-punching forming limit of a variable cross-section convex feature, so as to establish a specification indicating the design of a part subjected to the roll-punching forming process.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide an evaluation die for researching the forming limit of a roller punching process forming raised feature, so as to fill the blank in the field of research on the forming limit of the roller punching process forming raised feature.

According to the invention, the convex feature roll-punching forming limit evaluation die comprises an upper die set and a lower die set, wherein:

the upper die set comprises a plurality of upper die blocks, one side of each upper die block is arranged on the roller punching forming equipment, and the other side of each upper die block extends outwards to form a bulge;

the lower die set comprises a plurality of lower die blocks, one side of each lower die block is arranged on the roll punching forming equipment, and the other side of each lower die block extends inwards to form a groove matched with the corresponding protrusion;

the upper die set and the lower die set are matched with each other through the bulges and the grooves;

at least one upper die block is a sunken upper die block, a notch is formed in the convex surface of the sunken upper die block, at least one lower die block is a protruded lower die block, and a convex block matched with the notch is arranged in a groove of the protruded lower die block.

Preferably, the height of the bump is h, the diameter of the top end of the bump is d, the corresponding radius of the outer contour of the upper portion of the bump is r1, and the corresponding radius of the outer contour of the lower portion of the bump is r2, so that the bump characteristics are defined by the parameters h, d, r1 and r 2.

Preferably, a horizontal upper die block and a horizontal lower die block are further included, wherein:

the horizontal upper die block is connected with the concave upper die block,

the horizontal lower die block is connected with the protruding lower die block.

Preferably, the surface of the protrusion of the horizontal upper block and the surface of the groove of the horizontal lower block are horizontal planes.

Preferably, the corners of the upper die block and the lower die block are provided with chamfers.

According to the invention, the measuring method for evaluating the die based on the forming limit of the convex feature roll punch comprises the following steps:

a step of installing a die: respectively installing an upper die set and a lower die set on roll punching forming equipment;

the bump feature roll-punch forming test step: starting the roll punching forming equipment, taking down the test sample after the convex features are completely formed, and finishing the primary test; adjusting the parameters of the convex block and the notch, performing the step characteristic roll punching forming test again, and performing a plurality of tests aiming at each group of different parameters;

grid measurement and size measurement: carrying out grid measurement on a convex characteristic region of the forming sample piece, and further obtaining the main strain and the secondary strain of the region; measuring the size of the convex characteristic region of the forming sample to obtain the size precision;

a standardization step: after the primary strain and the secondary strain of a series of convex features with different sizes are obtained, the parameters of the convex blocks and the concave openings are standardized to obtain the forming limit of the convex features formed by the roll punching.

Compared with the prior art, the invention has the following beneficial effects:

1. the present invention can provide an accurate measurement of the roll-punch forming limit of raised features by adjusting the parameters d, h, r1 and r 2.

2. The invention can evaluate the forming limit of the convex characteristic roll punching for the plates with different thicknesses and different materials.

3. The invention comprises two equal section parts, and can eliminate the end influence in the forming limit evaluation process.

4. The die blocks included in the invention can be replaced, so that the service life is prolonged, and the cost is reduced.

5. The invention has simple structure, convenient use and higher flexibility.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a schematic view of a roll-punch forming limit evaluation die for raised features provided by the present invention;

FIG. 2 is a schematic view of a lower die set;

FIG. 3 is a top view of the lower die set;

FIG. 4 is a schematic view of an upper die set;

FIG. 5 is a top view of the upper die set;

FIG. 6 is a front view of an under bump mold block;

FIG. 7 is a top view of a recessed upper mold block;

FIG. 8 is a schematic cross-sectional view A-A of a top view of a recessed upper mold block;

the figures show that:

first horizontal upper die block 1

Concave upper die block 2

Second horizontal upper die block 3

First horizontal lower die block 4

Under bump mold block 5

Second horizontal lower die block 6

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

As shown in fig. 1, the raised feature roll-punch forming limit evaluation mold provided by the present invention includes an upper mold set and a lower mold set. The upper die set comprises three die blocks, namely a first horizontal upper die block 1, a sunken upper die block 2 and a second horizontal upper die block 3; the lower die set comprises three die blocks, namely a first horizontal lower die block 4, a lower bump die block 5 and a second horizontal lower die block 6; the upper die block and the lower die block comprise bolt hole structures so as to be matched with roll punching forming equipment; the upper die block and the lower die block include a chamfer feature to avoid interference during the rotational forming process. In the embodiment, the first horizontal upper die block 1 and the second horizontal upper die block 3 are uniform-section die blocks, and the concave upper die block 2 is a variable-section die block and comprises a concave feature; the first horizontal lower die block 4 and the second horizontal lower die block 6 are equal-section die blocks, and the lower bump die block 5 is a variable-section die block and comprises a convex feature. The first horizontal upper die block 1, the second horizontal upper die block 3, the first horizontal lower die block 4 and the second horizontal lower die block 6 can be replaced. The height of the bump of the under bump mold block is h, the diameter of the top end of the bump is d, the corresponding radius of the outer contour of the upper portion of the bump is r1, and the corresponding radius of the outer contour of the lower portion of the bump is r2, so that the characteristics of the bump are defined by the parameters h, d, r1 and r 2.

The invention also provides a method for measuring the forming limit by using the convex characteristic roll punching forming limit evaluation die. The steps of using the evaluation die provided by the invention to perform a raised feature roll-punch forming limit test comprise:

⑴ installing mould blocks, namely installing a first horizontal upper mould block 1, a concave upper mould block 2, a second horizontal upper mould block 3, a first horizontal lower mould block 4, a convex lower mould block 5 and a second horizontal lower mould block 6 on roll punching forming equipment respectively, wherein the variable cross-section mould block needs to be installed in the middle of the constant cross-section mould block to eliminate the end influence in the forming limit test process.

⑵, starting the roll punching forming device, taking down the test sample after the convex feature is completely formed, finishing the test, changing the parameters d, h, r1 and r2, carrying out the roll punching forming test again, and carrying out a plurality of tests to reduce the error according to each group of different parameters.

⑶, carrying out grid measurement on the convex characteristic region of the forming sample piece, further obtaining the main strain and the secondary strain of the region, and carrying out size measurement on the convex characteristic region of the forming sample piece, thus obtaining the related size precision.

⑷, after obtaining the primary and secondary strains for a series of different sized raised features, the parameters d, h, r1 and r2 are normalized based on specific requirements to obtain more intuitive roll-punch formed raised feature forming limits.

Based on the convex feature roll punching forming limit evaluation die, the convex feature roll punching forming limit can be accurately measured, and design criteria are provided for the design of roll punching forming parts. The method has important practical significance for popularizing the roll punching forming process and fills the gap in the domestic roll punching forming limit research field.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.

Claims

1. The utility model provides a protruding characteristic roll-punching forming limit aassessment mould which characterized in that, includes die set and bed die set, wherein:

2. The die of claim 1 wherein the bump has a height h, a bump tip diameter d, a bump upper portion outer profile corresponding to a radius r1, and a bump lower portion outer profile corresponding to a radius r2, the bump characteristics being defined by the parameters h, d, r1, and r 2.

3. The raised feature roll-punch forming limit evaluation die of claim 1, further comprising a horizontal upper die block and a horizontal lower die block, wherein:

the horizontal upper die block is connected with the concave upper die block,

4. The raised feature roll-punch forming limit evaluation die of claim 3, wherein the raised surface of the horizontal upper die block and the recessed surface of the horizontal lower die block are horizontal surfaces.

5. The raised feature roll-forming limit evaluation die of claim 1, wherein corners of the upper die block and the lower die block are each provided with a chamfer.

6. A measurement method of a raised feature roll-punch forming limit evaluation mold based on any one of claims 1 to 5, characterized by comprising the steps of: