A plastic bending strength experiment clamp

Abstract

The utility model discloses a kind of plastic bending strength experimental fixture, including support base, the surface both sides of support base are equipped with transmission box, the surface both sides of transmission box are rotatably installed with support roller, the surface one side of support base is equipped with positioning frame, the top one side of positioning frame is equipped with electric push rod, the bottom rotatably installed with extruding roller of electric push rod, transmission box is equipped with span adjustment mechanism between support roller. The utility model has following effect: the plastic workpiece needing to carry out bending strength detection is supported by two support rollers, then by span adjustment mechanism, the span between two support rollers can be adjusted according to the thickness of plastic workpiece, without artificial step-by-step measurement and adjustment, avoid the error and complex operation brought by artificial measurement and calculation, to effectively improve the accuracy of test data and the efficiency of bending strength measurement experiment.

Description

Technical Field

[0001] This utility model relates to the field of plastic testing technology, and more specifically, to a plastic bending strength test fixture. Background Technology

[0002] Bending strength testing of plastic products is one of the important methods for evaluating their mechanical properties, and it is widely used in materials research and development, quality control, and product certification. By measuring the mechanical response of plastics under bending loads, key performance indicators such as bending resistance, stiffness, and toughness can be effectively assessed. Currently, the commonly used testing method is the three-point bending test. This method uses a pair of support rollers to stably support both ends of the specimen, and a loading head above applies a vertically downward force at the mid-span of the specimen. Based on the data of downward pressure and displacement recorded during the test, the bending strength and bending modulus of the plastic product can be calculated.

[0003] While three-point bending fixtures are relatively mature technologies, they still present operational inconveniences in practical applications. Specifically, the span between the two support rollers must be precisely set according to the thickness of the plastic workpiece before testing. According to relevant testing standards (such as ISO 178 or ASTM D790), the span is typically a specific multiple of the sample thickness (e.g., 16:1). Therefore, the thickness of the plastic workpiece must be accurately measured before testing, and the required span calculated based on this value. The positions of the two support rollers then need to be manually adjusted. This process is not only cumbersome and time-consuming, but also prone to errors in measurement or adjustment, leading to span setting deviations. Improper span setting directly affects stress distribution, resulting in distorted test results and reduced testing accuracy. Utility Model Content

[0004] In view of the problems in the related technologies, this utility model proposes a plastic bending strength test fixture to overcome the above-mentioned technical problems existing in the existing related technologies.

[0005] Therefore, the specific technical solution adopted by this utility model is as follows:

[0006] A plastic bending strength test fixture includes a support base, transmission boxes mounted on both sides of the support base, support rollers rotatably mounted on both sides of the transmission boxes, a positioning frame mounted on one side of the support base, an electric push rod mounted on the top side of the positioning frame, a compression roller rotatably mounted on the bottom of the electric push rod, and a span adjustment mechanism provided between the transmission boxes and the support rollers.

[0007] Furthermore, in order to adjust the span between the two support rollers, the span adjustment mechanism includes a driven shaft rotatably mounted inside the transmission box, transmission screws connected to both sides of the driven shaft, an adjusting cylinder threadedly connected to the surface of the transmission screws, and one side of the adjusting cylinder rotatably connected to one end of the support roller.

[0008] Furthermore, in order to drive the driven shaft to rotate, a limit groove is opened on one side of the inner wall of the transmission box. A lifting block is slidably installed inside the limit groove. One end of the lifting block is connected to a lifting rack. A driven gear is installed at the middle position of the surface of the driven shaft. The driven gear meshes with the lifting rack.

[0009] Furthermore, in order to ensure that the plastic workpiece placed on the surface of the support roller has equal overhang lengths at both ends, a sliding groove is opened on one side of the surface of the support base, and a bidirectional screw is rotatably installed inside the sliding groove. Extrusion rods are threadedly connected to both sides of the surface of the bidirectional screw.

[0010] Furthermore, in order to compare and measure the rising height of the top of the lifting rack with the thickness of the plastic workpiece, a measuring rod is rotatably connected to the top of the lifting rack as it slides through the transmission box.

[0011] Furthermore, in order to detect the pressure applied by the electric actuator during bending measurement, a pressure sensor is installed at one end of the electric actuator.

[0012] Furthermore, to facilitate the twisting and rotation of the bidirectional screw, a twisting ring is connected to one end of the bidirectional screw.

[0013] The beneficial effects of this utility model are as follows:

[0014] The plastic workpiece to be tested for bending strength is supported by two support rollers. Then, by pulling the lifting rack in the span adjustment mechanism upward, the top of the lifting rack rises to the same height as the thickness of the plastic to be tested. As the lifting rack rises, it drives the two support rollers on the transmission screw to move relative to each other, realizing the rapid adjustment of the span between the two support rollers. This eliminates the need for manual step-by-step measurement and adjustment, avoiding errors and complex operations caused by manual measurement and calculation, thereby effectively improving the accuracy of test data and the efficiency of bending strength measurement experiments. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the surface structure of a plastic bending strength test fixture according to an embodiment of the present utility model;

[0017] Figure 2 This is a side view of a plastic bending strength testing fixture according to an embodiment of the present utility model;

[0018] Figure 3 This is a rear view of a plastic bending strength testing fixture according to an embodiment of the present utility model;

[0019] Figure 4 This is a schematic diagram of the surface structure of the measuring rod after rotation in a plastic bending strength test fixture according to an embodiment of the present utility model;

[0020] Figure 5 This is an internal cross-sectional view of the transmission box in a plastic bending strength test fixture according to an embodiment of the present utility model;

[0021] Figure 6 yes Figure 5 Enlarged view of point A in the middle;

[0022] Figure 7 This is a side view of the internal cross-section of the transmission box in a plastic bending strength test fixture according to an embodiment of the present utility model;

[0023] Figure 8 yes Figure 7 Enlarged diagram of point B in the middle.

[0024] In the picture:

[0025] 1. Support base; 2. Transmission box; 3. Support roller; 4. Positioning frame; 5. Electric push rod; 6. Extrusion roller; 7. Span adjustment mechanism; 701. Driven shaft; 702. Transmission screw; 703. Adjusting cylinder; 704. Limiting groove; 705. Lifting block; 706. Lifting rack; 707. Driven gear; 8. Sliding groove; 9. Bidirectional screw; 10. Extrusion rod; 11. Measuring rod; 12. Pressure sensor; 13. Tightening ring. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0027] According to an embodiment of the present invention, a plastic bending strength test fixture is provided.

[0028] like Figures 1-4As shown, a plastic bending strength test fixture according to an embodiment of the present invention includes a support base 1. A pair of transmission boxes 2 are installed on both sides of the surface of the support base 1. A pair of support rollers 3 are rotatably installed on both sides of the surface of the two transmission boxes 2 for stable support of the plastic workpiece to be tested. A positioning frame 4 is installed on one side of the surface of the support base 1. An electric push rod 5 is installed on the top side of the positioning frame 4. A squeezing roller 6 is rotatably installed on the bottom of the electric push rod 5. Through the two support rollers 3 and the squeezing roller 6 at the end of the electric push rod 5, a three-point bending fixture required for measuring the bending strength of the plastic workpiece can be formed. The squeezing roller 6 is driven to move downward by the electric push rod 5, so that the squeezing roller 6 can press down on the plastic workpiece for bending test. A span adjustment mechanism 7 is provided between the transmission box 2 and the support roller 3 for quickly adjusting the span between the two support rollers 3 according to the thickness of the plastic workpiece.

[0029] like Figures 2-8As shown, the span adjustment mechanism 7 includes a driven shaft 701 rotatably mounted inside the transmission box 2. Transmission screws 702 are connected to both sides of the surface of the driven shaft 701, with opposite threads on their surfaces. An adjusting cylinder 703 is threaded onto the surface of each transmission screw 702. One side of the adjusting cylinder 703 is rotatably connected to one end of the support roller 3. The driven shaft 701 drives the two transmission screws 702 to rotate, causing the transmission screws 702 to move relative to the adjusting cylinder 703, thus enabling the adjusting cylinder 703 to adjust the span of the two support rollers 3. A limit groove 704 is opened on one side of the inner wall of the transmission box 2. A lifting block 705 is slidably mounted inside the limit groove 704. One end of the lifting block 705 is connected to a lifting rack 706. A driven gear 707 is mounted at the center of the surface of shaft 701. The driven gear 707 meshes with a lifting rack 706. The up-and-down movement of the lifting rack 706 drives the driven gear 707 to rotate, which in turn drives the transmission shaft to rotate, thus providing power for the span adjustment of the two support rollers 3. Through the transmission ratio between the lifting rack 706 and the transmission gear, and the transmission ratio between the transmission screw 702 and the adjusting cylinder 703, the ratio of the distance the lifting rack 706 moves up and down to the distance the adjusting cylinder 703 moves on the transmission screw 702 is 1:8. This allows the span between the two support rollers 3 to be 16 times the thickness of the plastic workpiece when the moving height of the lifting rack 706 is the same as the thickness of the plastic workpiece (according to relevant test standard ISO). 178 or ASTM D790); A sliding groove 8 is opened on one side of the surface of the support base 1. A bidirectional screw 9 is rotatably installed inside the sliding groove 8. A pressing rod 10 is threadedly connected to both sides of the surface of the bidirectional screw 9. By rotating the bidirectional screw 9, the pair of pressing rods 10 on the surface of the bidirectional screw 9 approach each other, which can squeeze and push the plastic workpiece on the surface of the two support rollers 3, so that the two ends of the workpiece are overhanging with equal lengths; The top of the lifting rack 706 slides through the transmission box 2 and is rotatably connected to a measuring rod 11, which is used to compare and measure the rising height of the top of the lifting rack 706 with the thickness of the plastic workpiece after rotation; A pressure sensor 12 is installed at one end of the electric push rod 5, which is used to detect the pressure applied by the electric push rod 5 during bending measurement; A turning ring 13 is connected to one end of the bidirectional screw 9, which is used to facilitate the turning and adjustment of the bidirectional screw 9.

[0030] In practical use, before testing the bending strength of plastic workpieces, the plastic sample to be tested is first placed horizontally between two support rollers 3, with its bottom in contact with the surface of the support rollers 3. By manually rotating the turning ring 13 at one end of the bidirectional screw 9, the bidirectional screw 9 is driven to rotate, and the extrusion rods 10 connected to its two sides move relative to each other in the sliding groove 8. When the extrusion rods 10 move towards the middle, their ends push the two ends of the plastic workpiece, causing it to slide on the support rollers 3 until the lengths of the two ends are equal, thus achieving automatic centering and positioning of the sample. Subsequently, the lifting mechanisms in the two transmission boxes 2 are simultaneously pulled upwards. The rack 706 moves such a distance that it is exactly equal to the thickness of the plastic workpiece. When the rack 706 moves upward, it drives the driven gear 707 in the transmission box 2 to rotate. The driven gear 707 is fixedly mounted on the driven shaft 701, thereby driving the driven shaft 701 to rotate. When the driven shaft 701 rotates under the drive of the driven gear 707, the two transmission screws 702 rotate synchronously. Since the screw threads are opposite, the two adjusting cylinders 703 move in opposite directions on the screws, thereby driving the support rollers 3 on both sides to move away from or towards each other synchronously in the horizontal direction, thus realizing the adjustment of the span.

[0031] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A plastic bending strength testing fixture, characterized in that, Includes a support base (1), a transmission box (2) is installed on both sides of the surface of the support base (1), a support roller (3) is rotatably installed on both sides of the surface of the transmission box (2), a positioning frame (4) is installed on one side of the surface of the support base (1), an electric push rod (5) is installed on the top side of the positioning frame (4), a squeezing roller (6) is rotatably installed on the bottom of the electric push rod (5), and a span adjustment mechanism (7) is provided between the transmission box (2) and the support roller (3). The span adjustment mechanism (7) includes a driven shaft (701) rotatably installed inside the transmission box (2), a transmission screw (702) connected to both sides of the surface of the driven shaft (701), an adjusting cylinder (703) threadedly connected to the surface of the transmission screw (702), and one side of the surface of the adjusting cylinder (703) rotatably connected to one end of the support roller (3). A limit groove (704) is opened on one side of the inner wall of the transmission box (2). A lifting block (705) is slidably installed inside the limit groove (704). A lifting rack (706) is connected to one end of the lifting block (705). A driven gear (707) is installed in the middle of the surface of the driven shaft (701). The driven gear (707) meshes with the lifting rack (706).

2. The plastic bending strength testing fixture according to claim 1, characterized in that, A sliding groove (8) is opened on one side of the surface of the support base (1). A double-acting screw (9) is rotatably installed inside the sliding groove (8). A pressing rod (10) is threaded on both sides of the surface of the double-acting screw (9).

3. The plastic bending strength testing fixture according to claim 1, characterized in that, The top of the lifting rack (706) slides through the transmission box (2) and is rotatably connected to the measuring rod (11).

4. A plastic bending strength testing fixture according to claim 1, characterized in that, A pressure sensor (12) is installed at one end of the electric push rod (5).

5. A plastic bending strength testing fixture according to claim 2, characterized in that, One end of the double-ended screw (9) is connected to a screwing ring (13).

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