Clamp for extreme point cold bending test of ultrahigh-strength steel

Abstract

The utility model relates to a clamp for extreme point cold bending test of ultrahigh strength steel, which comprises a connecting piece, a pressure head clamp, a pressure head, a base, a sliding table, a supporting roller frame, a roller, a double-end threaded column and a roller frame moving mechanism, the pressure head clamp is connected to the lower end of the connecting piece, and the pressure head clamp is provided with a pressure head inserting groove; the pressing head is fixed in a pressing head inserting groove of the pressing head clamp through a pin, the sliding table is fixed to the upper end of the base, the supporting roller frames are symmetrically arranged in pairs, the two rollers are installed on the supporting roller frames respectively, and the supporting roller frames can relatively slide on the sliding table under driving of the roller frame moving mechanism. The double-end threaded columns are connected to the two sides of the two supporting roller frames in a penetrating mode and locked and positioned through the clamp locking nuts. According to the utility model, the limit tip cold bending test of a high-strength material with the tensile strength below 2Gpa can be met; the pressure heads with different thicknesses can be conveniently replaced, rapid disassembly and assembly on the universal testing machine can be realized, the distance between the rollers can be conveniently adjusted, and the device is not easy to damage and small in size.

Description

Technical Field

[0001] The utility model relates to the technical field of metal material evaluation, in particular to a clamp for extreme sharp cold bending testing of ultra-high strength steel. Background Art

[0002] The extreme sharp cold bending performance of ultra-high-strength steel is currently a new important performance evaluation index to measure the toughness of ultra-high-strength steel plates. With the development of automobile lightweight and safety technology, the strength level of vehicle body safety parts has gradually increased, and the proportion of ultra-high-strength automotive steel used in vehicle bodies has become increasingly higher. As the strength level of vehicle body steel plates increases, their general toughness and plasticity decrease, making them more susceptible to brittle fracture in collisions. In response to the demand for ultra-high-strength steel extreme sharp cold bending performance testing for automotive product certification and application, the test was conducted with reference to the VDA238-100 method. However, due to the influence of fixture stiffness, support roller movement, support roller spacing control, pressure head deflection, friction during the test, etc., the test results of different fixtures have large deviations. Therefore, for the sharp-angle cold bending test, it is necessary to design a test fixture that can be used for ultra-high-strength steels such as 2GPa hot-formed steel, and is simple to load and unload and easy to operate. Utility Model Content

[0003] The purpose of the utility model is to provide a fixture for the extreme sharp cold bending test of ultra-high-strength steel, which solves the problems of insufficient fixture rigidity, deflection of the pressure head, sliding of the support roller during the pressing process, and numerous steps for loading and unloading the fixture in the current extreme sharp cold bending test of ultra-high-strength steel with a tensile strength of 1000Mpa to 2GPa. It can easily replace pressure heads of different thicknesses, can be quickly disassembled and assembled on a universal testing machine, and can conveniently adjust the distance between the rollers. It simplifies the experimental process, greatly improves the experimental efficiency, and can meet the increasing demand for extreme sharp cold bending experiments on high-strength steel.

[0004] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0005] A fixture for extreme sharp cold bending testing of ultra-high strength steel, comprising a connecting piece, a pressure head fixture, a pressure head, a base, a slide, a support roller frame, a roller, a double-headed threaded column, and a roller frame moving mechanism, wherein the pressure head fixture is connected to the lower end of the connecting piece, the pressure head fixture is provided with a pressure head plug-in slot, and the pressure head is fixed in the pressure head plug-in slot of the pressure head fixture by a pin, the slide is fixed to the upper end of the base, the support roller frames are symmetrically arranged in pairs, and two rollers are respectively installed on the support roller frames. The support roller frames can slide relatively on the slide under the drive of the roller frame moving mechanism, and the double-headed threaded column is connected to both sides of the two support roller frames and is locked and positioned by the clamp locking nut.

[0006] The roller frame moving mechanism includes a handwheel and a bidirectional threaded rod. The two ends of the bidirectional threaded rod are provided with threads of different rotation directions and are respectively screwed to two supporting roller frames. The slide platform is provided with a slideway arranged parallel to the bidirectional threaded rod. The supporting roller frame is slidably connected to the slideway, and the handwheel is fixed to one end of the bidirectional threaded rod.

[0007] A scale is also provided on the side surfaces of the two support roller frames, and the calibrated "0" position of the scale coincides with the position of the tangent point when the two rollers are brought close together.

[0008] The connecting piece is connected to the pressure head fixture through threads and is locked and fixed by a pressure head locking nut.

[0009] The connecting piece is provided with a slot hole for installation in cooperation with the universal testing machine.

[0010] The base is provided with a slot hole for installation in cooperation with the universal testing machine.

[0011] The pressure head includes a clamping part and a test part. The clamping part and the test part are integrally formed. The test part is in the shape of a long strip. The clamping part is laterally engaged with the pressure head plug-in groove. A transverse slot hole is provided on the side of the clamping part. The pin is screwed into the transverse slot hole of the clamping part from the side of the pressure head fixture to axially lock the pressure head in place.

[0012] Compared with the prior art, the beneficial effects of the utility model are:

[0013] The utility model can meet the requirements of extreme sharp cold bending test of high-strength materials with tensile strength below 2Gpa; it can conveniently replace pressure heads of different thicknesses, can be quickly disassembled and assembled on a universal testing machine, and can conveniently adjust the distance between rollers; it is not easy to be damaged and has a small size. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a three-dimensional structural schematic diagram of the utility model.

[0015] Figure 2 It is the front view of the utility model.

[0016] Figure 3 It is a right view of the utility model.

[0017] Figure 4 It is a left view of the utility model.

[0018] Figure 5 It is a top view of the utility model.

[0019] Figure 6 It is a bottom view of the utility model.

[0020] In the figure: 1-connecting part, 2-pressure head locking nut, 3-pressure head fixture, 4-pressure head, 5-roller, 6-ruler, 7-support roller frame, 8-double threaded column, 9-clamp locking nut, 10-handwheel, 11-7-head screw, 12-slide, 13-upper plate, 14-side plate, 15-bottom plate, 16-bidirectional threaded rod, 17-pin, 18-screw bracket. DETAILED DESCRIPTION

[0021] The following is a further description of the embodiments of the present invention in conjunction with the accompanying drawings:

[0022] like Figure 1-Figure 6 As shown, a fixture for extreme sharp cold bending test of ultra-high strength steel includes a connecting piece 1, a pressure head fixture 3, a pressure head 4, a base, a slide 12, a support roller frame 7, a roller 5, a double-headed threaded column 16, and a roller frame moving mechanism. The pressure head fixture 3 is connected to the lower end of the connecting piece 1, and the pressure head fixture 3 is provided with a pressure head plug-in groove, and the pressure head 4 is fixed in the pressure head plug-in groove of the pressure head fixture 3 by a pin 17. The slide 12 is fixed to the upper end of the base, and the support roller frames 7 are symmetrically arranged in pairs, and two rollers 5 are respectively installed on the support roller frames 7. The support roller frames 7 can slide relatively on the slide 12 under the drive of the roller frame moving mechanism, and the double-headed threaded column 8 is connected to both sides of the two support roller frames 7 and is locked and positioned by the fixture locking nut 9.

[0023] The base is a hollow frame composed of two side plates 14, an upper plate 13 and a bottom plate 15. The bottom plate 15 is provided with round holes for matching with the universal testing machine and with pin holes for positioning.

[0024] The roller frame moving mechanism includes a handwheel 10 and a bidirectional threaded rod 16. The two ends of the bidirectional threaded rod 16 are provided with threads of different rotation directions and are respectively screwed to the two supporting roller frames 7. The slide 12 is provided with a slideway arranged parallel to the bidirectional threaded rod 16. The supporting roller frame 7 is slidably connected to the slideway. The handwheel 10 is fixed to one end of the bidirectional threaded rod 16.

[0025] The support roller frame 7 is composed of a main board and two bracket side plates. The two bracket side plates are vertically fixedly connected to the main board, and the rollers are installed between the two side plates through bearings. The two oppositely rotating threaded segments of the bidirectional threaded rod 16 are respectively screwed to the main boards of the two support roller frames 7. When the bidirectional threaded rod 16 rotates, the two support roller frames 7 can slide relative to or in the opposite direction due to the setting of the oppositely rotating threaded segments. The two ends of the bidirectional threaded rod 16 extend out of the two support roller frames 7, one end is connected to the hand wheel 10, and the other end is mounted on the screw bracket 18. The screw bracket 18 is provided with an open groove, and the other end of the bidirectional threaded rod 16 can be locked by the 7-head screw 11 to position it.

[0026] A scale 6 is also provided on the side of the two support roller frames 7, and the calibration "0" position of the scale 6 coincides with the position of the tangent point when the two rollers 5 are close together. The scale is used to measure the distance between the two rollers 5.

[0027] The connecting piece 1 is connected to the pressure head fixture 3 through threads and is locked and fixed by the pressure head locking nut 2.

[0028] The connecting piece 1 is provided with a slot hole for mounting in cooperation with the universal testing machine.

[0029] The base is provided with a slot hole for installation in cooperation with the universal testing machine.

[0030] The pressure head 4 includes a clamping part and a test part. The clamping part and the test part are integrally formed. The test part is in the shape of a long strip. The clamping part is laterally engaged with the pressure head plug-in groove of the pressure head fixture 3. A transverse slot hole is provided on the side of the clamping part. The pin 17 is screwed into the transverse slot hole of the clamping part from the side of the pressure head fixture 3 to axially lock and position the pressure head 4.

[0031] The length of the pressure head fixture 3 is the same as that of the pressure head 4. The pressure head insertion groove is transversely arranged at the center line position of the bottom of the pressure head fixture 3. The clamping part of the pressure head 4 is plugged into the pressure head insertion groove. The pin 17 is threadedly connected to the pressure head fixture 3, and the clamping part of the pressure head 4 is tightened and fixed after being locked.

[0032] The thickness of the test part of the indenter 4 of the utility model has two specifications, namely: the sharp corner radius r is 0.2mm and 0.4mm. The steps of the extreme sharp cold bending test implemented by the utility model are as follows:

[0033] Take 2Gpa hot-pressed steel and cut it into 60mm×60mm squares. Deburr and chamfer at 45° on both end faces along the width direction, and the chamfer width is less than 0.5mm.

[0034] 1. Install the indenter 4 and the base on the universal testing machine.

[0035] 2. Place a 2Gpa hot-pressed steel plate sample on two rollers 5 so that the rolling direction of the sample is perpendicular or parallel to the loading edge of the pressure head 4.

[0036] 3. Start the downward movement of the pressure head 4 so that the sample loading line completely coincides with the edge of the pressure head 4.

[0037] 4. After adjusting the relative position between the specimen and the tooling, apply a preload force of 30N to the specimen.

[0038] 5. Set the quasi-static loading rate of the indenter 4 to 5-20 mm / min.

[0039] 6. Start the equipment to perform continuous bending loading on the specimen, collect the loading load and displacement data in real time, and stop the test when the load on the specimen bending load-displacement curve drops to 10% of the peak load or visible cracks appear.

[0040] 7. Manually drive the pressure head 4 to separate it from the sample and take out the sample.

[0041] 8. Use professional angle measurement tools to measure the bending angle.

Claims

1. A fixture for extreme tip cold bending test of ultra-high strength steel, characterized in that: It includes a connecting piece, a pressure head clamp, a pressure head, a base, a slide, a support roller frame, a roller, a double-headed threaded column, and a roller frame moving mechanism. The pressure head clamp is connected to the lower end of the connecting piece. The pressure head clamp is provided with a pressure head plug-in groove, and the pressure head is fixed in the pressure head plug-in groove of the pressure head clamp by a pin. The slide is fixed to the upper end of the base. The support roller frames are symmetrically arranged in pairs, and two rollers are respectively installed on the support roller frames. The support roller frames can slide relatively on the slide under the drive of the roller frame moving mechanism. The double-headed threaded column is connected to both sides of the two support roller frames and is locked and positioned by the clamp locking nut.

2. The fixture for extreme tip cold bending test of ultra-high strength steel according to claim 1, characterized in that: The roller frame moving mechanism includes a handwheel and a bidirectional threaded rod. The two ends of the bidirectional threaded rod are provided with threads of different rotation directions and are respectively screwed to two supporting roller frames. The slide platform is provided with a slideway arranged parallel to the bidirectional threaded rod. The supporting roller frame is slidably connected to the slideway, and the handwheel is fixed to one end of the bidirectional threaded rod.

3. The fixture for extreme tip cold bending test of ultra-high strength steel according to claim 1, characterized in that: A scale is also provided on the side of the two support roller frames, and the calibration "0" position of the scale coincides with the tangent point position when the two rollers are close together.

4. The fixture for extreme tip cold bending test of ultra-high strength steel according to claim 1, characterized in that: The connecting piece is connected to the pressure head fixture through threads and is locked and fixed by a pressure head locking nut.

5. A fixture for extreme tip cold bending test of ultra-high strength steel according to claim 1 or 4, characterized in that: The connecting piece is provided with a slot hole for installation in cooperation with the universal testing machine.

6. The fixture for extreme tip cold bending test of ultra-high strength steel according to claim 1, characterized in that: The base is provided with a slot hole for installation in cooperation with the universal testing machine.

7. The fixture for extreme tip cold bending test of ultra-high strength steel according to claim 1, characterized in that: The pressure head includes a clamping part and a test part. The clamping part and the test part are integrally formed. The test part is in the shape of a long strip. The clamping part is laterally engaged with the pressure head plug-in groove. A transverse slot hole is provided on the side of the clamping part. The pin is screwed into the transverse slot hole of the clamping part from the side of the pressure head fixture to axially lock the pressure head in place.

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