A friction head for a scratch tester

Abstract

This invention relates to a friction head for a scratch tester. The friction head includes a rod, a positioning mechanism disposed at the bottom of the rod, and sandpaper detachably disposed at the bottom of the positioning mechanism. The bottom surface of the positioning mechanism is a downwardly convex arc surface, and the sandpaper is adapted to the bottom surface of the positioning mechanism. Compared with the prior art, this invention facilitates sandpaper replacement, improves testing accuracy and flexibility, and the replacement operation is simple and quick. The arc-shaped bottom of the sandpaper makes line contact with the material to be tested, thus allowing for a direct reciprocating straight path, greatly simplifying the complexity of path design and providing good test repeatability, thereby ensuring testing accuracy. It also reduces the precision requirements for instrument calibration, lowers the operational difficulty, and improves testing efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of scratch testers and relates to a friction head used for a scratch tester. Background Art

[0002] The scratch tester is a device used to test the scratch resistance of materials. It is widely used in the automotive industry, mainly to test the wear resistance of smooth and textured plastic trims in automotive interior and exterior trims.

[0003] The existing scratch tester mainly includes a sample loading platform, a friction head, a friction head bracket and a power device. When in use, the material to be tested is placed on the sample loading platform and fixed, then the friction head is placed on the friction head bracket, and a weight of the required weight is placed on the friction head or the friction head bracket. Then, driven by the power device, the sample loading platform drives the material to be tested to reciprocate horizontally along a pre-designed route. The scratch resistance of the material is judged by the continuous friction of the bottom of the friction head on the material and the state of the material after friction.

[0004] The friction head currently used mainly includes a vertical rod and a cylindrical nylon block arranged at the bottom of the rod. When in use, the rod is fixed to the friction head bracket, and a weight is placed on the rod. Then, the bottom of the nylon block is brought into contact with the surface of the material to be tested, and friction is generated by the relative movement between the bottom of the nylon block and the material to be tested. However, this type of friction head has many problems, such as:

[0005] 1. It is inconvenient to replace the nylon block, and as the use time increases, the bottom of the nylon block will wear unevenly, affecting the accuracy of the test results;

[0006] 2. The nylon block is cylindrical, and the contact surface between its bottom and the material to be tested is a circular surface. Therefore, when designing the movement path of the material, it is necessary to design a complex Lissajous figure, which not only increases the cumbersomeness of the test process, but also has poor test repeatability, thus affecting the test accuracy;

[0007] 3. If the rod column is not kept vertical and tilted to a certain extent, the bottom of the cylindrical nylon block will not be able to fully contact the material to be tested, resulting in the test being unable to proceed normally. Summary of the invention

[0008] The purpose of the present invention is to overcome the defects of the prior art and provide a friction head for a scratch tester to improve the test accuracy.

[0009] The purpose of the present invention can be achieved by the following technical solutions:

[0010] A friction head for a scratch tester, the friction head comprises a rod column, a positioning mechanism arranged at the bottom of the rod column, and sandpaper detachably arranged at the bottom of the positioning mechanism, the bottom surface of the positioning mechanism is a downwardly convex arc surface, and the sandpaper is adapted to the bottom surface of the positioning mechanism. The sandpaper is detachably mounted on the arc-shaped bottom surface of the positioning mechanism, which is not only convenient for replacing the sandpaper, but also because the lowest point of the arc-shaped bottom surface is a horizontal line, the circular contact surface between the traditional cylindrical nylon block and the material to be tested is replaced by a line contact, so there is no need to use a complex Lissajous figure path.

[0011] Furthermore, the angle between the rod and the vertical direction is 0-5°. Since the bottom surface of the positioning mechanism is a downwardly convex arc surface, even if the rod is tilted at a certain angle, there will still be a horizontal contact line between the arc surface at the bottom of the positioning mechanism and the material to be tested.

[0012] Furthermore, the positioning mechanism includes a positioning ring sleeved on the bottom of the rod column, a convex body fixedly arranged at the bottom of the positioning ring, and a sandpaper clamping assembly, wherein the bottom surface of the convex body is a downwardly convex arc surface, and the sandpaper is arranged at the bottom of the convex body and is matched with the bottom surface of the convex body. The sandpaper clamping assembly is used to clamp and fix the sandpaper to realize the detachable installation of the sandpaper.

[0013] Furthermore, the bottom of the rod column and the positioning ring are connected by threads. The bottom of the rod column is screwed into the positioning ring through the threads to achieve a fixed connection between the rod column and the positioning ring.

[0014] Furthermore, a positioning ring installation groove matched with the positioning ring is opened on the top of the convex body, and the positioning ring is fixedly arranged in the positioning ring installation groove.

[0015] Furthermore, the bottom surface of the positioning ring installation groove is a plane. The bottom of the rod column passes through the positioning ring and is tightly against the bottom surface of the positioning ring installation groove to ensure a stable connection.

[0016] Furthermore, the top surface of the convex body is a plane, the bottom surface is an arc surface, the sandpaper is in a long strip shape, and the sandpaper is bent into an arc surface and closely attached to the bottom surface of the convex body. The sandpaper can be selected from ordinary long strip sandpaper. When in use, the sandpaper of the required length is cut, and then the sandpaper is bent into an arc surface and closely attached to the bottom surface of the convex body, and the sandpaper is fixed to the bottom surface of the convex body by a sandpaper clamping assembly.

[0017] Furthermore, both ends of the convex body are provided with cylindrical pin installation grooves, and the sandpaper clamping assembly includes a pair of cylindrical pins respectively arranged in the two cylindrical pin installation grooves, and the two ends of the sandpaper are respectively extended into the two cylindrical pin installation grooves and located between the cylindrical pins and the convex body. After the sandpaper is pressed against the bottom surface of the convex body, the two ends of the sandpaper are placed in the cylindrical pin installation grooves, and then the cylindrical pins are placed in the two cylindrical pin installation grooves to press the sandpaper, and the two ends of the sandpaper are fixed to achieve detachable installation of the sandpaper.

[0018] Furthermore, the sandpaper clamping assembly further comprises a pair of elastic tightening strips respectively arranged on both sides of the convex body, and the elastic tightening strips are simultaneously sleeved on the two cylindrical pins. The elastic tightening strips are elastic, and after the cylindrical pins are placed in the two cylindrical pin installation grooves, one of the elastic tightening strips is simultaneously sleeved on one end of the two cylindrical pins, and the other elastic tightening strip is simultaneously sleeved on the other end of the two cylindrical pins, and then the two cylindrical pins are fixed by the two elastic tightening strips, so that the two cylindrical pins are kept in the cylindrical pin installation grooves.

[0019] Furthermore, both ends of the cylindrical pin are provided with elastic tightening strip installation grooves, and both ends of the elastic tightening strip are provided with through holes adapted to the elastic tightening strip installation grooves. The inner diameter of the through hole is slightly smaller than the outer diameter of the cylindrical pin. The through hole of the elastic tightening strip is inserted into the elastic tightening strip installation groove of the cylindrical pin to ensure a stable connection between the two cylindrical pins and the two elastic tightening strips.

[0020] In actual application, the present invention selects sandpaper of appropriate mesh size according to the roughness requirements of the friction head in the test standard, cuts the sandpaper to the required size and places it close to the bottom surface of the convex body, and fixes the sandpaper with two cylindrical pins and two elastic tightening strips; then the friction head is installed on the scratch tester as a whole, and a weight of appropriate weight is put on the rod column as required, and then the scratch tester is started for testing; during the test, the sample loading platform of the scratch tester drives the material to be tested to reciprocate linearly, so that the bottom of the sandpaper and the surface of the material to be tested rub against each other, and scratches are left on the surface of the sample, and the scratch resistance of the sample is judged according to the depth of the scratches. The sample can be a plastic plate, a test plate coated with paint and varnish, etc.

[0021] Compared with the prior art, the present invention has the following characteristics:

[0022] 1) By utilizing the cooperation of two cylindrical pins, two elastic tightening strips and the two ends of the convex body, the sandpaper is detachably arranged at the bottom of the convex body, so that it is convenient to replace sandpaper of different roughness according to different test requirements, thereby increasing the load, or replacing new sandpaper when the sandpaper is worn, thereby improving the test accuracy and test flexibility, and the replacement operation is simple and fast;

[0023] 2) The circular contact surface between the traditional cylindrical nylon block and the material to be tested is replaced by a line contact between the arc bottom of the sandpaper and the material to be tested. By changing the contact mode, it is no longer necessary to use a complex Lissajous figure path when planning the path, and a reciprocating straight line path can be directly used, which greatly simplifies the complexity of the path design and has good test repeatability, thereby ensuring the test accuracy;

[0024] 3) Since the sandpaper is bent into an arc surface that is consistent with the shape of the bottom surface of the convex body, even if the rod column is tilted at a certain angle, there will still be a horizontal contact line between the arc surface and the material to be tested, so that the line contact state can always be maintained, which greatly reduces the accuracy requirements for instrument debugging, reduces the difficulty of operation, and improves test efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0026] Figure 2 It is a schematic diagram of the structure of the convex body in the present invention;

[0027] Figure 3 It is a structural schematic diagram of a cylindrical pin in the present invention;

[0028] Figure 4 It is a schematic diagram of the structure of the elastic tightening strip in the present invention;

[0029] Description of the markings in the figure:

[0030] 1—rod column, 2—sandpaper, 3—positioning ring, 4—convex body, 5—positioning ring mounting groove, 6—cylindrical pin mounting groove, 7—cylindrical pin, 8—elastic tightening strip, 9—elastic tightening strip mounting groove, 10—through hole. DETAILED DESCRIPTION

[0031] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0032] Example:

[0033] like Figure 1 The friction head for a scratch tester shown in the figure comprises a rod column 1, a positioning mechanism arranged at the bottom of the rod column 1, and sandpaper 2 detachably arranged at the bottom of the positioning mechanism. The bottom surface of the positioning mechanism is a downwardly convex arc surface, and the sandpaper 2 is adapted to the bottom surface of the positioning mechanism.

[0034] The angle between the pole 1 and the vertical direction is 0-5°.

[0035] The positioning mechanism includes a positioning ring 3 sleeved on the bottom of the pole 1, a convex body 4 fixedly arranged at the bottom of the positioning ring 3, and a sandpaper clamping assembly, the bottom surface of the convex body 4 is a downwardly convex arc surface, and the sandpaper 2 is arranged at the bottom of the convex body 4 and is adapted to the bottom surface of the convex body 4. The bottom of the pole 1 and the positioning ring 3 are connected by threads.

[0036] like Figure 2 As shown, the top of the convex body 4 is provided with a positioning ring mounting groove 5 adapted to the positioning ring 3, and the positioning ring 3 is fixedly arranged in the positioning ring mounting groove 5. The bottom surface of the positioning ring mounting groove 5 is a plane. The top surface of the convex body 4 is a plane, and the bottom surface is an arc surface. The sandpaper 2 is in the shape of a long strip, and the sandpaper 2 is bent into an arc surface and is tightly attached to the bottom surface of the convex body 4. Both ends of the convex body 4 are provided with cylindrical pin mounting grooves 6, and the sandpaper clamping assembly includes a pair of cylindrical pins 7 respectively arranged in the two cylindrical pin mounting grooves 6, and the two ends of the sandpaper 2 extend into the two cylindrical pin mounting grooves 6 respectively, and are located between the cylindrical pins 7 and the convex body 4. The sandpaper clamping assembly also includes a pair of elastic tightening strips 8 respectively arranged on both sides of the convex body 4, and the elastic tightening strips 8 are simultaneously sleeved on the two cylindrical pins 7.

[0037] like Figure 3 As shown, both ends of the cylindrical pin 7 are provided with elastic tightening strip mounting grooves 9. Figure 4 As shown, both ends of the elastic tightening strip 8 are provided with through holes 10 adapted to the elastic tightening strip mounting grooves 9 .

[0038] In actual application, according to the roughness requirements of the friction head in the test standard, select sandpaper 2 with a suitable mesh number, cut the sandpaper 2 to the required size and then cling it to the bottom surface of the convex body 4, and fix the sandpaper 2 with two cylindrical pins 7 and two elastic tightening strips 8; then install the friction head as a whole on the scratch tester, and put a weight of suitable weight on the rod column 1 as needed, and then start the scratch tester for testing; during the test, the sample loading platform of the scratch tester drives the material to be tested to reciprocate in a straight line, so that the bottom of the sandpaper 2 and the surface of the material to be tested rub against each other, and leave scratches on the surface of the sample, and the scratch resistance of the sample is judged according to the depth of the scratches.

[0039] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A friction head for a scratch tester, characterized in that: The friction head comprises a rod column (1), a positioning mechanism arranged at the bottom of the rod column (1), and sandpaper (2) detachably arranged at the bottom of the positioning mechanism, wherein the bottom surface of the positioning mechanism is a downwardly convex arc surface, and the sandpaper (2) is adapted to the bottom surface of the positioning mechanism; The positioning mechanism comprises a positioning ring (3) sleeved on the bottom of the rod column (1), a convex body (4) fixedly arranged on the bottom of the positioning ring (3), and a sandpaper clamping assembly, the bottom surface of the convex body (4) is a downwardly convex arc surface, and the sandpaper (2) is arranged on the bottom of the convex body (4) and is adapted to the bottom surface of the convex body (4); The bottom of the rod column (1) and the positioning ring (3) are connected by threads; The top surface of the convex body (4) is a plane, and the bottom surface is a curved surface; the sandpaper (2) is in the shape of a long strip, and the sandpaper (2) is bent into a curved surface and is closely attached to the bottom surface of the convex body (4); Both ends of the convex body (4) are provided with cylindrical pin mounting grooves (6), the sandpaper clamping assembly comprises a pair of cylindrical pins (7) respectively arranged in the two cylindrical pin mounting grooves (6), and the two ends of the sandpaper (2) respectively extend into the two cylindrical pin mounting grooves (6) and are located between the cylindrical pins (7) and the convex body (4).

2. A friction head for a scratch tester according to claim 1, characterized in that: The angle between the pole (1) and the vertical direction is 0-5°.

3. A friction head for a scratch tester according to claim 1, characterized in that: A positioning ring installation groove (5) adapted to the positioning ring (3) is provided on the top of the convex body (4), and the positioning ring (3) is fixedly arranged in the positioning ring installation groove (5).

4. A friction head for a scratch tester according to claim 3, characterized in that: The bottom surface of the positioning ring installation groove (5) is a plane.

5. The friction head for a scratch tester according to claim 1, characterized in that: The sandpaper clamping assembly further comprises a pair of elastic tightening strips (8) respectively arranged on both sides of the convex body (4), and the elastic tightening strips (8) are simultaneously sleeved on the two cylindrical pins (7).

6. A friction head for a scratch tester according to claim 5, characterized in that: Both ends of the cylindrical pin (7) are provided with elastic tightening strip installation grooves (9), and both ends of the elastic tightening strip (8) are provided with through holes (10) that are compatible with the elastic tightening strip installation grooves (9).

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