Auxiliary clamp for testing bonding strength of coating

Abstract

The invention discloses an auxiliary clamp for testing the bonding strength of a coating, which belongs to the technical field of surface treatment and coating manufacturing, is used for carrying out traction test on the bonding strength of the coating, and is used for clamping two butt joint parts which are bonded into a whole and stretching the butt joint parts perpendicular to the horizontal plane through a traction test machine which stretches in opposite vertical directions. The clamping head of the upper butt joint part is firstly clamped, after the two butt joint parts naturally droop, the lower clamping head is clamped, through natural droop operation, under the matching structure of the rotating ball head and the ball groove, the clamping error generated during clamping of a traction machine is overcome, and the plane where a test sample is pasted is parallel to the horizontal plane; the function of testing the tensile force perpendicular to the test sample is realized.

Description

Technical Field

[0001] This invention belongs to the field of surface treatment and manufacturing coating technology, and specifically relates to an auxiliary fixture for testing coating adhesion strength. Background Technology

[0002] In industrial manufacturing, coating technology is widely used in the surface treatment of metals, ceramics, and composite materials to improve their wear resistance, corrosion resistance, and functionality. The bonding strength between the coating and the substrate is one of the core indicators for evaluating coating performance, directly affecting product reliability and service life. The traction test is a commonly used method for testing coating bonding strength. It directly reflects the interfacial bonding force between the coating and the substrate through a tensile force perpendicular to the coating surface. This method is characterized by its intuitive operation and high degree of data quantification, making it particularly suitable for evaluating the bonding performance of brittle coatings or under complex working conditions. However, the accuracy of the traction test depends on the stability of the testing device and the precision of the applied force direction; traditional fixtures have significant limitations in practical applications.

[0003] Traditional traction test fixtures typically employ a rigid clamping structure, requiring the test sample to be precisely aligned and fixed beforehand to ensure the tensile force direction is perpendicular to the coating surface. However, in actual operation, the clamping mechanism of the traction test machine may deviate from the ideal direction due to machining inaccuracies or installation errors, resulting in additional shear forces or bending moments that affect the accuracy of the test results. This necessitates repeated manual calibration of the sample position, which is time-consuming, labor-intensive, and difficult to ensure consistency, significantly increasing the operational difficulty. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide an auxiliary fixture for coating bonding strength testing, which can automatically calibrate the direction of force application and eliminate clamping errors, so as to improve testing accuracy and efficiency.

[0005] To achieve the above objectives, the present invention provides the following technical solution: This invention includes two docking parts, each with an adhesive surface for attaching test samples. The two docking parts are clamped by a traction testing machine and pulled in opposite directions. Each docking part includes a clamping head, a rotating middle seat, and a connecting base. The clamping head includes a clamping section and a rotating ball head. One end of the clamping section is fixedly clamped by the traction testing machine, and the other end is integrally connected to the rotating ball head. A ball groove is formed at the upper end of the rotating middle seat, and the ball groove has an inner groove structure that mates with the rotating ball head. The ball groove portion protrudes from the end face of the rotating middle seat, and the rotating ball head is rotatably disposed within the ball groove. The connecting base is disposed at the other end of the rotating middle seat, and the connecting base includes a connecting post connected to the rotating middle seat and an adhesive seat at the lower end of the connecting post. The adhesive surface is the bottom surface of the adhesive seat.

[0006] Furthermore, a cylindrical inner cavity is formed inside the lower end of the rotating seat, and a through hole is formed through the lower end of the rotating seat. An inner baffle with an edge larger than the through hole and smaller than the cross-section of the inner cavity is fixedly connected to the upper end of the connecting column. The inner baffle is located inside the inner cavity, and the outer diameter of the connecting column is smaller than the cross-section of the through hole. During the traction test, the inner baffle slides and shifts along the bottom surface of the inner cavity toward the through hole to eliminate the shear stress at the docking part.

[0007] Furthermore, a pin is fixedly provided at the upper middle part of the inner baffle. A through hole is opened on the top surface of the inner cavity facing the rotating ball head for the pin to pass through. A insertion hole is opened at the end of the rotating ball head away from the clamping section for the pin to be inserted. Both the insertion hole and the through hole cooperate with the pin. The connecting base is moved upward so that the pin passes through the through hole and the insertion hole in sequence, thereby fixing the clamping head, the rotating middle base and the connecting base in the radial direction.

[0008] Furthermore, the top of the pin is provided with a soft, easily expandable ball piston, and the end face of the insertion hole is provided with a plug hole for the rotating ball piston to be inserted. The plug hole is smaller than the rotating ball piston, so that the ball piston and the plug hole are in an interference fit.

[0009] Furthermore, a number of steel balls are rotatably disposed on the end face of the inner baffle facing the adhesive seat. The steel balls are partially exposed from the end face of the inner baffle. During the traction test, the steel balls abut against the bottom surface of the inner cavity.

[0010] Furthermore, the adhesive seat includes an upper seat and a lower seat, the upper seat is fixedly connected to the connecting column, the lower seat slides into the upper seat laterally, and the adhesive surface is located on the outer end face of the lower seat.

[0011] Furthermore, one end of the clamping section is a sheet-like structure for clamping by the traction testing machine, and the cylindrical structure axis of the clamping section coincides with the central axis of the rotating ball head.

[0012] Furthermore, the inner baffle has a disc-shaped structure, the connecting column is coaxially connected to the inner baffle, and the steel ball is located at the outer edge of the bottom end face of the inner baffle.

[0013] Furthermore, a transverse groove with a convex cross-section is opened through the upper end face, and a transverse pin that mates with the transverse groove is fixed on the upper end face.

[0014] Furthermore, the top surface of the inner cavity facing the rotating ball head is provided with a groove that matches the shape of the inner baffle.

[0015] The beneficial effects of this invention are as follows: This invention is used for traction testing of coating bonding strength. A traction testing machine, using vertically opposite stretching directions, clamps and stretches two bonded joints perpendicular to the horizontal plane. First, the clamping head of the upper joint is clamped. After the two joints hang naturally, the lower clamping head is clamped. Through this natural hanging operation, and with the cooperation structure of the rotating ball head and ball groove, the clamping error generated during clamping by the traction machine is overcome, ensuring that the plane of the bonded test sample is parallel to the horizontal plane, thus achieving the function of traction testing perpendicular to the test sample.

[0016] Other advantages, objectives, and features of the invention will be set forth in the following description and will be apparent to those skilled in the art in some respects, or may be learned by practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0017] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following figures are provided for illustration: Figure 1 This is a schematic diagram of the auxiliary fixture according to an embodiment of the present invention; Figure 2 This is a cross-sectional view of the docking portion according to an embodiment of the present invention; Figure 3 for Figure 2 Enlarged view of point B; Figure 4 This is a cross-sectional view of the rotating center seat according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the clamping head according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of the connecting base according to an embodiment of the present invention; The following labels are used in the attached diagram: A. Butt joint; b. Adhesive surface; 1. Clamping head; 11. Clamping section; 12. Rotating ball head; 121. Insertion hole; 122. Plug hole; 2. Rotating middle seat; 21. Ball groove; 22. Inner cavity; 23. Through hole; 24. Through hole; 25. Embedded groove; 3. Connecting base; 31. Connecting column; 32. Adhesive seat; 321. Upper seat; 322. Lower seat; 323. Horizontal groove; 324. Horizontal pin; 33. Inner baffle; 331. Steel ball; 34. Insert pin; 35. Ball head piston; 4. Test sample. Detailed Implementation

[0018] This invention discloses an auxiliary fixture for testing coating adhesion strength, such as... Figure 1As shown, it includes two docking parts A, each with an adhesive surface b for attaching the test sample 4. The two docking parts A are clamped by a traction testing machine and pulled in opposite directions. Each docking part A includes a clamping head 1, a rotating center seat 2, and a connecting base 3. Figure 2 and Figure 5 As shown, the clamping head 1 includes a clamping section 11 and a rotating ball head 12. One end of the clamping section 11 is a plate-like structure for clamping by a traction testing machine. The cylindrical axis of the clamping section 11 coincides with the central axis of the rotating ball head 12. One end of the clamping section 11 is fixedly clamped by the traction testing machine, and the other end is fixedly connected to the rotating ball head 12. A ball groove 21 is formed on the upper end of the rotating middle seat 2. The ball groove 21 has an inner groove structure that cooperates with the rotating ball head 12. Part of the ball groove 21 protrudes from the end face of the rotating middle seat 2. The rotating ball head 12 is rotatably disposed in the ball groove 21, and the connecting base 3 is disposed at the other end of the rotating middle seat 2. The connecting base 3 includes a connecting column 31 connected to the rotating middle seat 2 and an adhesive seat 32 at the lower end of the connecting column 31. The adhesive surface b is the bottom surface of the adhesive seat 32. During the traction test, the two docking parts A are bonded to the test sample 4. The traction test machine first clamps the clamping head 1 of the upper docking part A, and the two docking parts A hang down naturally. Then, the traction test machine clamps the clamping head 1 of the lower docking part A.

[0019] This auxiliary fixture is used to perform a traction test on the coating bonding strength. The traction tester, which stretches in opposite vertical directions, clamps and stretches the two bonded joint parts A perpendicular to the horizontal plane. First, the clamping head 1 of the upper joint part A is clamped. After the two joint parts A hang down naturally, the lower clamping head 1 is clamped. Through the operation of hanging down naturally, the clamping error generated during clamping by the rotating ball head 12 and the ball groove 21 is overcome, so that the plane of the bonded test sample 4 is parallel to the horizontal plane, and the function of perpendicularly tensile force test on the test sample 4 is realized.

[0020] In further proposals, such as Figure 2 , Figure 4 As shown, a cylindrical inner cavity 22 is opened inside the lower end of the rotating seat 2. A through hole 23 is opened through the inner cavity 22 and the lower end of the rotating seat 2. An inner baffle 33 with an edge larger than the through hole 23 and smaller than the cross-section of the inner cavity 22 is fixedly connected to the upper end of the connecting column 31. The inner baffle 33 is located inside the inner cavity 22. The outer diameter of the connecting column 31 is smaller than the cross-section of the through hole 23. During the traction test, the inner baffle 33 slides and moves along the bottom surface of the inner cavity 22 toward the through hole 23 to eliminate the shear stress of the docking part A.

[0021] This structure provides a lateral displacement structure for the connecting base 3, so that after the auxiliary clamp is clamped at both ends, the inner baffle 33 moves a small distance within the inner cavity 22, providing a certain translation distance for the two connecting bases 3, thus eliminating the positional offset of the connecting base 3 caused by the clamping error of the traction machine.

[0022] In further proposals, such as Figure 2 and Figure 4 As shown, a pin 34 is fixedly provided at the upper middle part of the inner baffle 33. A through hole 24 for the pin 34 to pass through is opened on the top surface of the inner cavity 22 facing the rotating ball head 12. An insertion hole 121 for the pin 34 to be inserted is opened at the end of the rotating ball head 12 away from the clamping section 11. Both the insertion hole 121 and the through hole 24 are engaged with the pin 34. A groove 25 that matches the shape of the inner baffle 33 is also opened on the top surface of the inner cavity 22 facing the rotating ball head 12. The connecting base 3 is moved upward so that the pin 34 passes through the through hole 24 and the insertion hole 121 in sequence, so that the clamping head 1, the rotating middle seat 2 and the connecting seat are fixed in the radial direction.

[0023] After the test sample 4 is bonded, the clamping head 1, the rotating middle seat 2 and the connecting base 3 are coaxially connected by the pin 34, so that the connecting column 31 is located in the middle of the through hole 23. The two docking parts A after coaxial connection are directly clamped by the traction testing machine and then stretched. During the stretching process, the rotation of the ball groove 21 and the rotating ball head 12, as well as the small-distance translation of the inner baffle 33 in the inner cavity 22, can balance the tensile force on the test sample 4 into a vertical tensile force. By setting this structure, the assembly simplicity of this device is improved, the installation difficulty is reduced, and the transverse shear stress of the test sample 4 can still be eliminated.

[0024] In further proposals, such as Figure 3 and Figure 6 As shown, the top of the pin 34 is also provided with a soft and easily expandable ball head piston 35. The end face of the insertion hole 121 is provided with a plug hole 122 for the rotating ball head piston 12 to be inserted. The plug hole 122 is smaller than the rotating ball head piston 12, so that the ball head piston 35 and the plug hole 122 are in an interference fit state.

[0025] By setting the ball piston 35 and the plug hole 122, the pin 34 is given a certain retention capacity in the insertion hole 121, which prevents the joint of the docking part A from falling during the vertical clamping process.

[0026] In further proposals, such as Figure 2 , Figure 3 and Figure 6As shown, a plurality of steel balls 331 are rotatably disposed on the end face of the inner baffle 33 facing the adhesive seat 32. The steel balls 331 are partially exposed from the end face of the inner baffle 33. The inner baffle 33 has a disc-shaped structure. The connecting post 31 is coaxially connected to the inner baffle 33. The steel balls 331 are located at the outer edge of the bottom end face of the inner baffle 33. During the traction test, the steel balls 331 abut against the bottom surface of the inner cavity 22.

[0027] By setting steel balls 331, the inner baffle 33 is provided with the ability to slide within the inner cavity 22, thereby eliminating the transverse shear stress caused by friction.

[0028] In further proposals, such as Figure 6 As shown, the adhesive base 32 includes an upper base 321 and a lower base 322. The upper base 321 is fixedly connected to the connecting post 31. A transverse groove 323 with a convex cross-section is opened through the end face of the upper base 321. A transverse pin 324 that cooperates with the transverse groove 323 is fixedly provided on the end face of the upper base 321. The lower base 322 slides into the upper base 321 and is inserted laterally. The adhesive surface b is located on the outer end face of the lower base 322.

[0029] This structure provides a detachable mounting base 322 for the test sample 4, which facilitates the bonding of the test plane and the bonding surface, prevents the adhesive from falling onto other structures of the mating part A during the application process, reduces the operating volume of the mating part A during the bonding process, and lowers the operating difficulty.

[0030] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. An auxiliary fixture for testing the bonding strength of a coating, comprising two mating portions (A), each of the two mating portions (A) having an adhesive surface (b) for attaching a test sample (4), the two mating portions (A) being clamped by a traction testing machine and pulled in opposite directions, characterized in that: The docking part (A) includes a clamping head (1), a rotating middle seat (2), and a connecting base (3); the clamping head (1) includes a clamping section (11) and a rotating ball head (12). One end of the clamping section (11) is fixedly clamped by the traction testing machine, and the other end is fixedly connected to the rotating ball head (12); a ball groove (21) is opened at the upper end of the rotating middle seat (2). The ball groove (21) has an inner groove structure that cooperates with the rotating ball head (12). The ball groove (21) is partially exposed from the end face of the rotating middle seat (2). The rotating ball head (12) is rotatably disposed in the ball groove (21). The connecting base (3) is disposed at the other end of the rotating middle seat (2). The connecting base (3) includes a connecting column (31) connected to the rotating middle seat (2) and an adhesive seat (32) at the lower end of the connecting column (31). The adhesive surface (b) is the bottom surface of the adhesive seat (32).

2. The auxiliary fixture for testing coating adhesion strength according to claim 1, characterized in that: The lower end of the rotating seat (2) has a cylindrical inner cavity (22), and the inner cavity (22) and the lower end of the rotating seat (2) have a through hole (23). The upper end of the connecting column (31) is fixedly connected to an inner baffle (33) with an edge larger than the through hole (23) and smaller than the cross-section of the inner cavity (22). The inner baffle (33) is located inside the inner cavity (22), and the outer diameter of the connecting column (31) is smaller than the cross-section of the through hole (23). During the traction test, the inner baffle (33) slides and moves along the inner cavity (22) toward the bottom surface of the through hole (23) to eliminate the shear stress of the docking part (A).

3. The auxiliary fixture for testing coating adhesion strength according to claim 2, characterized in that: The upper middle part of the inner baffle (33) is also fixed with a pin (34). The inner cavity (22) has a through hole (24) for the pin (34) to pass through on the top surface of the rotating ball head (12). The end of the rotating ball head (12) away from the clamping section (11) has a socket (121) for the pin (34) to be inserted. The socket (121) and the through hole (24) are both engaged with the pin (34). The connecting base (3) is moved up so that the pin (34) passes through the through hole (24) and the socket (121) in sequence, so that the clamping head (1), the rotating middle seat (2) and the connecting seat are fixed in the radial direction.

4. The auxiliary fixture for testing coating adhesion strength according to claim 3, characterized in that: The top of the pin (34) is also provided with a soft and easily expandable ball piston (35). The end face of the insertion hole (121) is provided with a plug hole (122) for the rotating ball piston (12) to be inserted. The plug hole (122) is smaller than the rotating ball piston (12), so that the ball piston (35) and the plug hole (122) are in an interference fit state.

5. The auxiliary fixture for testing coating adhesion strength according to claim 4, characterized in that: A number of steel balls (331) are rotatably disposed on the end face of the inner baffle (33) facing the adhesive seat (32). The steel balls (331) are partially exposed from the end face of the inner baffle (33). During the traction test, the steel balls (331) abut against the bottom surface of the inner cavity (22).

6. The auxiliary fixture for testing coating adhesion strength according to claim 5, characterized in that: The adhesive seat (32) includes an upper seat (321) and a lower seat (322). The upper seat (321) is fixedly connected to the connecting post (31). The lower seat (322) slides into the upper seat (321) laterally. The adhesive surface (b) is located on the outer end face of the lower seat (322).

7. The auxiliary fixture for testing coating adhesion strength according to claim 6, characterized in that: One end of the clamping section (11) is a sheet-like structure for clamping by the traction testing machine, and the cylindrical axis of the clamping section (11) coincides with the central axis of the rotating ball head (12).

8. The auxiliary fixture for testing coating adhesion strength according to claim 7, characterized in that: The inner baffle (33) has a disc-shaped structure, the connecting column (31) is coaxially connected to the inner baffle (33), and the steel ball (331) is located at the outer edge of the bottom surface of the inner baffle (33).

9. The auxiliary fixture for testing coating adhesion strength according to claim 8, characterized in that: The upper seat (321) has a transverse groove (323) with a convex cross section through the end face, and the upper seat (321) is fixed with a transverse pin (324) that cooperates with the transverse groove (323).

10. The auxiliary fixture for testing coating adhesion strength according to claim 9, characterized in that: The inner cavity (22) has a groove (25) on its top surface facing the rotating ball head (12) that matches the shape of the inner baffle (33).

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