A rapid full inspection device for threaded holes of MIM parts
Patent Information
- Application Number
- CN202522606034.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-09
- Publication Date
- 2026-09-04
- Estimated Expiration
- 2035-12-09
AI Technical Summary
其中，在进行螺纹孔机加工时，会使用数控铣床将MIM零件上的螺纹孔加工到位，但是在加工过程中，由于刀具磨损、碎屑残留、素材来料差异等问题，在进行大批量生产时，无法保证螺丝拧进螺纹孔时100%顺通，而为了确保MIM零件的出厂质量，保证零件组装时不出现螺丝拧不进螺纹孔的情况，在MIM零件出货前，需要对加工后的螺纹孔进行检测，也就是需要使用螺丝100%全检MIM零件的所有螺纹孔，一方面检测螺丝能否顺通，另一方面检测螺纹孔的有效圈数是否符合要求
[0011]This invention is used for the rapid inspection of threaded holes in MIM parts. Before use, first fix the hollow set screw set to the lower part of the screwdriver bit, and then install the half-threaded screw on the screw sleeve. During installation, the bolt head of the half-threaded screw is inserted into the blind hole of the screw sleeve through the rectangular opening, and the smooth part of the half-threaded screw is inserted into the U-shaped opening, exposing the thread inspection part of the half-threaded screw. Then, screw the hollow set screw into the blind hole of the screw sleeve through the thread until the working end of the screwdriver bit extends into the non-circular groove of the bolt head of the half-threaded screw, and presses the bolt head tightly against the bottom of the blind hole to fix the half-threaded screw. Finally, install the drive end of the screwdriver bit on the electric screwdriver to complete the installation of this device. When using this device to inspect the threaded holes of MIM parts, the thread size and number of turns of the thread detection part of the half-thread screw are determined according to the threaded hole to be inspected. The inspection principle is as follows: Start the electric screwdriver, which drives the bit and the half-thread screw to rotate in sequence, and simultaneously drives the hollow set screw and the screw sleeve to rotate, so that the thread detection part of the half-thread screw is screwed into the threaded hole of the MIM part to be inspected. If the thread detection part is completely submerged in the threaded hole of the MIM part, it means that the threaded hole of the MIM part is qualified. Conversely, if the thread detection part is not completely submerged in the threaded hole of the MIM part, it means that the threaded hole of the MIM part is unqualified. This device uses an electric screwdriver to replace manual screw tightening for full inspection of threaded holes. It can quickly complete the inspection of each threaded hole, significantly improving the efficiency of full inspection, reducing the labor intensity and workload of workers, and lowering inspection costs. It is suitable for the mass production of MIM parts. Secondly, in this device, the number of thread turns on the thread detection unit is determined by the required number of effective turns on the threaded hole. That is, the number of effective thread turns required for the threaded hole is set to the same number of turns on the thread detection unit. Thus, as long as the thread detection unit can be fully inserted into the threaded hole, the number of effective thread turns on the threaded hole will not be less than the required number, avoiding the need for manual counting of effective thread turns. The determination of the number of turns is no longer dependent on manual labor, thereby avoiding the influence of human factors. This invention solves the problem of misjudgment during threaded hole inspection due to errors in manual counting, improving the accuracy and precision of threaded hole inspection and effectively ensuring the factory quality of MIM products. Furthermore, this device uses a half-threaded screw to inspect the threaded holes. Due to wear and other reasons, the half-threaded screw needs to be replaced after inspecting a certain number of threaded holes to ensure thread inspection accuracy. At this time, simply loosen the screw sleeve, disengaging the connection between the screw sleeve and the hollow set screw, allowing the working end of the screwdriver bit to extend out of the non-circular groove of the bolt head. This allows the old or damaged half-threaded screw to be removed, and then a new half-threaded screw can be installed to complete the fixation. The process of removing and replacing the half-threaded screw is convenient and quick, achieving rapid disassembly and replacement. In summary, this invention has the advantages of high work efficiency, low inspection cost, and high inspection accuracy.
Smart Images
Figure CN224719329U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the technical field of rapid inspection equipment for threaded holes in MIM parts, specifically to a rapid full inspection device for threaded holes in MIM parts. Background Technology
[0002] MIM is an abbreviation for Metal Injection Molding, an advanced manufacturing technology that mixes metal powder with a binder, forms the mixture through injection molding, and then debindes and sinters to produce high-precision, complex-shaped small metal parts. The general process flow is as follows: injection molding - debinding - sintering - shaping - machining threaded holes - screw inspection. During threaded hole machining, a CNC milling machine is used to machine the threaded holes on the MIM part. However, due to tool wear, debris residue, and differences in incoming materials, it is impossible to guarantee 100% smooth screw insertion into the threaded holes during mass production. To ensure the quality of MIM parts before shipment and to prevent screws from failing to screw into the threaded holes during assembly, the machined threaded holes need to be inspected before shipment. This involves a 100% inspection of all threaded holes on the MIM part using screws. This inspection checks both the smoothness of screw insertion and whether the effective number of turns of the thread meets the requirements.
[0003] Currently, the full inspection of screws in the threaded holes of MIM products is mostly done manually. Operators manually screw the screws into the threaded holes of the MIM parts, ensuring the screws reach the bottom of the holes to confirm proper thread flow. Simultaneously, when manually unscrewing the screws, the operator must count the effective number of turns to ensure it meets the required number. This process presents several problems: First, a single MIM part often has several threaded holes, making the full inspection of a single part time-consuming, labor-intensive, costly, and inefficient, which is detrimental to the mass production of MIM parts. Second, counting the effective turns of the threaded holes manually is highly susceptible to human error, easily leading to errors such as over- or under-counting, resulting in misjudgments during the full inspection and affecting the quality of the MIM products leaving the factory. Therefore, developing a rapid full inspection device for the threaded holes of MIM parts that is highly efficient, low-cost, and highly accurate is objectively necessary. Utility Model Content
[0004] The purpose of this invention is to provide a rapid full inspection device for threaded holes in MIM parts that has high work efficiency, low full inspection cost, and high inspection accuracy.
[0005] The purpose of this utility model is achieved as follows: It includes an electric screwdriver and a screwdriver bit mounted on the electric screwdriver. The screwdriver bit is sequentially connected to a hollow set screw, a screw sleeve, and a half-thread screw. The hollow set screw has a through hole coaxially machined inside, and an external thread machined on its outer wall. The screw sleeve has a blind hole coaxially machined inside, and an internal thread matching the external thread of the hollow set screw is machined on the upper side wall of the blind hole. A rectangular opening is machined on the lower side wall of the blind hole. A U-shaped opening facing the same direction as the rectangular opening is machined on the screw sleeve at the bottom of the blind hole. The half-thread screw includes a bolt head, a smooth shank, and a thread detection section connected in sequence. A non-circular groove matching the working end of the screwdriver bit is machined on the bolt head. The screwdriver bit is fixedly inserted into the through hole of the hollow set screw. The hollow set screw is screwed into the blind hole through its external thread. The half-thread screw is mounted on the bottom of the screw sleeve through the rectangular opening and the U-shaped opening, with the working end of the screwdriver bit extending into the non-circular groove of the bolt head.
[0006] Furthermore, the screwdriver bit and the through hole of the hollow set screw are fastened by an interference fit.
[0007] Furthermore, the working end of the bit has a hexagonal structure, and the cross-section of the non-circular groove of the bolt head is hexagonal.
[0008] Furthermore, the end of the U-shaped opening is semi-circular, and the semi-circle is coaxially arranged with the screw sleeve, and the radius of the semi-circle is the same as the radius of the smooth rod.
[0009] Furthermore, the bit has a stepped shape from the drive end to the working end, decreasing in size, and the hollow set screw is installed on the step near the working end.
[0010] Furthermore, anti-slip blocks are provided on the outer wall of the screw sleeve.
[0011] This invention is used for the rapid inspection of threaded holes in MIM parts. Before use, first fix the hollow set screw set to the lower part of the screwdriver bit, and then install the half-threaded screw on the screw sleeve. During installation, the bolt head of the half-threaded screw is inserted into the blind hole of the screw sleeve through the rectangular opening, and the smooth part of the half-threaded screw is inserted into the U-shaped opening, exposing the thread inspection part of the half-threaded screw. Then, screw the hollow set screw into the blind hole of the screw sleeve through the thread until the working end of the screwdriver bit extends into the non-circular groove of the bolt head of the half-threaded screw, and presses the bolt head tightly against the bottom of the blind hole to fix the half-threaded screw. Finally, install the drive end of the screwdriver bit on the electric screwdriver to complete the installation of this device. When using this device to inspect the threaded holes of MIM parts, the thread size and number of turns of the thread detection part of the half-thread screw are determined according to the threaded hole to be inspected. The inspection principle is as follows: Start the electric screwdriver, which drives the bit and the half-thread screw to rotate in sequence, and simultaneously drives the hollow set screw and the screw sleeve to rotate, so that the thread detection part of the half-thread screw is screwed into the threaded hole of the MIM part to be inspected. If the thread detection part is completely submerged in the threaded hole of the MIM part, it means that the threaded hole of the MIM part is qualified. Conversely, if the thread detection part is not completely submerged in the threaded hole of the MIM part, it means that the threaded hole of the MIM part is unqualified. This device uses an electric screwdriver to replace manual screw tightening for full inspection of threaded holes. It can quickly complete the inspection of each threaded hole, significantly improving the efficiency of full inspection, reducing the labor intensity and workload of workers, and lowering inspection costs. It is suitable for the mass production of MIM parts. Secondly, in this device, the number of thread turns on the thread detection unit is determined by the required number of effective turns on the threaded hole. That is, the number of effective thread turns required for the threaded hole is set to the same number of turns on the thread detection unit. Thus, as long as the thread detection unit can be fully inserted into the threaded hole, the number of effective thread turns on the threaded hole will not be less than the required number, avoiding the need for manual counting of effective thread turns. The determination of the number of turns is no longer dependent on manual labor, thereby avoiding the influence of human factors. This invention solves the problem of misjudgment during threaded hole inspection due to errors in manual counting, improving the accuracy and precision of threaded hole inspection and effectively ensuring the factory quality of MIM products. Furthermore, this device uses a half-threaded screw to inspect the threaded holes. Due to wear and other reasons, the half-threaded screw needs to be replaced after inspecting a certain number of threaded holes to ensure thread inspection accuracy. At this time, simply loosen the screw sleeve, disengaging the connection between the screw sleeve and the hollow set screw, allowing the working end of the screwdriver bit to extend out of the non-circular groove of the bolt head. This allows the old or damaged half-threaded screw to be removed, and then a new half-threaded screw can be installed to complete the fixation. The process of removing and replacing the half-threaded screw is convenient and quick, achieving rapid disassembly and replacement. In summary, this invention has the advantages of high work efficiency, low inspection cost, and high inspection accuracy. Attached Figure Description
[0012] Figure 1 This is a schematic diagram of the external structure of this utility model; Figure 2 This is a cross-sectional structural diagram of the present invention; Figure 3 This is a schematic diagram of the structure of the bit 2 in this utility model; Figure 4 This is a schematic diagram of the hollow set screw 3 in this utility model; Figure 5 This is a schematic diagram of the screw sleeve 4 in this utility model; Figure 6 This is a schematic diagram of the structure of the semi-threaded screw 5 in this utility model; In the diagram: 1-Electric screwdriver, 2-Bit, 3-Hollow set screw, 4-Screw sleeve, 5-Half thread screw, 6-Rectangular opening, 7-U-shaped opening, 8-Bolt head, 9-Smooth shaft, 10-Thread detection section, 11-Anti-slip block. Detailed Implementation
[0013] The present invention will be further described below with reference to the accompanying drawings, but this description is not intended to limit the present invention in any way. Any changes or improvements made based on the present invention shall fall within the protection scope of the present invention.
[0014] like Figures 1-6 As shown, this utility model includes an electric screwdriver 1 and a screwdriver bit 2 mounted on the electric screwdriver 1. The electric screwdriver 1 is an existing device used to drive the screwdriver bit 2 to rotate. A hollow set screw 3, a screw sleeve 4, and a half-thread screw 5 are sequentially connected to the screwdriver bit 2. The hollow set screw 3 has a through hole coaxially machined inside, and an external thread machined on the outer wall of the hollow set screw 3. The screw sleeve 4 has a blind hole coaxially machined inside, and an internal thread matching the external thread of the hollow set screw 3 is machined on the upper side wall of the blind hole. A rectangular... The screw sleeve 4 at the bottom of the blind hole has a U-shaped opening 7 that faces the same direction as the rectangular opening 6. The half-thread screw 5 includes a bolt head 8, a smooth shank 9, and a thread detection part 10 connected in sequence. The bolt head 8 has a non-circular groove that matches the working end of the bit 2. The bit 2 is fixedly inserted into the through hole of the hollow set screw 3. The hollow set screw 3 is screwed into the blind hole through the thread. The half-thread screw 5 is installed at the bottom of the screw sleeve 4 through the rectangular opening 6 and the U-shaped opening 7, and the working end of the bit 2 extends into the non-circular groove of the bolt head 8.
[0015] This utility model is used for rapid detection of threaded holes in MIM parts. Before use, the device is installed by first fixing the hollow set screw 3 to the lower part of the bit 2, and then installing the half-threaded screw 5 on the screw sleeve 4. During installation, the bolt head 8 of the half-threaded screw 5 is inserted into the blind hole of the screw sleeve 4 through the rectangular opening 6, and the smooth part 9 of the half-threaded screw 5 is inserted into the U-shaped opening 7, exposing the thread detection part 10 of the half-threaded screw 5. Then, the hollow set screw 3 is screwed into the blind hole of the screw sleeve 4 through the thread until the working end of the bit 2 extends into the non-circular groove of the bolt head 8 of the half-threaded screw 5, and the bolt head 8 is pressed tightly against the bottom of the blind hole to fix the half-threaded screw 5. Finally, the drive end of the bit 2 is installed on the electric screwdriver 1, thus completing the installation of the device.
[0016] When using this device to inspect the threaded holes of MIM parts, the thread size and number of turns of the thread detection part 10 of the half-thread screw 5 are determined according to the threaded hole to be inspected. The inspection principle is as follows: Start the electric screwdriver 1, which drives the bit 2 and the half-thread screw 5 to rotate in sequence, and simultaneously drives the hollow set screw 3 and the screw sleeve 4 to rotate, so that the thread detection part 10 of the half-thread screw 5 is screwed into the threaded hole of the MIM part to be inspected. If the thread detection part 10 is completely submerged in the threaded hole of the MIM part, it means that the threaded hole of the MIM part is qualified. Conversely, if the thread detection part 10 cannot be completely submerged in the threaded hole of the MIM part, it means that the threaded hole of the MIM part is unqualified.
[0017] This device uses an electric screwdriver 1 to replace manual screw tightening for full inspection of threaded holes. It can quickly complete the inspection of each threaded hole, significantly improving the efficiency of full inspection, reducing the labor intensity and workload of workers, and lowering inspection costs. It is suitable for the current mass production of MIM parts. Secondly, in this device, the number of thread turns on the thread detection unit 10 is determined according to the required number of effective turns on the threaded hole. That is, the number of effective threads required for the threaded hole is set to the same number on the thread detection unit 10. Thus, as long as the thread detection unit 10 can be fully inserted into the threaded hole, the number of effective thread turns on the threaded hole will not be less than the required number. This avoids the need for manual counting of effective thread turns, eliminating the influence of human factors and solving the problem of errors easily caused by manual counting. The device addresses the issue of misjudgment in full inspection of threaded holes, improving the precision and accuracy of threaded hole inspection and effectively ensuring the factory quality of MIM products. Furthermore, this device utilizes a half-thread screw 5 to inspect threaded holes. Due to wear and other reasons, after inspecting a certain number of threaded holes, the half-thread screw 5 needs to be replaced to ensure thread inspection accuracy. To do this, simply unscrew the screw sleeve 4, loosening the connection between the screw sleeve 4 and the hollow set screw 3, allowing the working end of the bit 2 to extend out of the non-circular groove of the bolt head 8. This allows the old or damaged half-thread screw 5 to be removed from the screw sleeve 4. Then, a new half-thread screw 5 can be installed using the aforementioned method to complete the fixation. The disassembly and replacement of the half-thread screw 5 is convenient and quick, achieving rapid disassembly and replacement, thereby improving the efficiency of full inspection of threaded holes in MIM parts.
[0018] Preferably, the fixing method between the bit 2 and the through hole of the hollow set screw 3 is an interference fit. In actual use, other methods can also be selected for fixing the two as needed, such as spot welding positioning. It is only necessary to ensure that there is no relative rotation between the bit 2 and the hollow set screw 3. The advantage of using an interference fit is that when the hollow set screw 3 needs to be removed, it is not easy to damage the bit 2. However, when spot welding positioning is used, it is necessary to cut the weld and grind the spot weld area, which can easily damage the bit 2 and reduce the service life of the bit 2.
[0019] Preferably, the working end of the bit 2 has a hexagonal structure, and the cross-section of the non-circular groove of the bolt head 8 is hexagonal. Generally, the working end of the bit 2 can be a hexagonal structure to match the hexagonal groove on the bolt head 8. In this way, when the bit 2 rotates, the half-threaded screw 5 can be rotated through the cooperation and restriction between the two. In this device, the main function of the hollow set screw 3 and the screw sleeve 4 is to realize the quick disassembly and assembly of the half-threaded screw 5, and to fix the position of the half-threaded screw 5.
[0020] The end of the U-shaped opening 7 is semi-circular, and the semi-circular part is coaxial with the screw sleeve 4. The radius of the semi-circular part is the same as the radius of the smooth part 9. When the semi-threaded screw 5 is inserted into the screw sleeve 4, the semi-circular end plays a role in positioning and limiting the semi-threaded screw 5. When the smooth part 9 of the semi-threaded screw 5 contacts the semi-circular end of the U-shaped opening 7, it means that the semi-threaded screw 5 has been installed in place. At this time, the axis of the semi-threaded screw 5 is coaxial with the bit 2, screw sleeve 4 and other parts. The working end of the bit 2 can easily extend into the non-circular groove of the bolt head 8, making installation more convenient and with higher installation accuracy.
[0021] In this device, the bit 2 is inserted inside the hollow set screw 3. For ease of installation, the bit 2 is stepped from the drive end to the working end, with the size decreasing. The hollow set screw 3 is installed on the step near the working end. Thus, during installation, the working end of the bit 2 with the smallest diameter passes through the hollow set screw 3 first. Since the diameter of the working end of the bit 2 is smaller than the diameter of the through hole of the hollow set screw 3, the installation can be relatively smooth, and the working end of the bit 2 will not be damaged during the installation process. Then, the next step of the bit 2 is inserted into the hollow set screw 3 for fixation.
[0022] The outer wall of the screw sleeve 4 is provided with an anti-slip block 11. During the installation and disassembly of this device, the screw sleeve 4 needs to be rotated. However, in actual operation, it was found that during the rotation of the screw sleeve 4, due to the smooth outer wall of the screw sleeve 4, it is easy to slip, which affects the installation and disassembly of the device. In order to solve this problem, the anti-slip block 11 is set. By setting the anti-slip block 11, the force point for rotating the screw sleeve 4 is increased, thereby solving the slippage problem and ensuring the quick installation and disassembly of the device.
[0023] The thread count, number of turns, and other parameters of the thread detection part 10 of the semi-threaded screw 5 in this device should match the thread hole of the MIM part to be inspected. Standard parts can also be selected when they meet the requirements. The standard is DIN 7964 (E)-1990.
[0024] In actual use, the utility model is used for detecting MIM parts with 6 M3 threaded holes. A CNC milling machine is used to process the 6 threaded holes on the MIM parts in place. During processing, problems such as tool wear, debris residue, and differences in incoming raw materials make it impossible to guarantee 100% smooth screwing of screws into the threaded holes during mass production. The device is used for full inspection of threaded holes, requiring that the effective number of turns of the threaded holes is greater than or equal to 10 turns. For the selected half-threaded screw 5, the number of thread turns in its thread detection part 10 is 10 turns. During detection, if all threads of the thread detection part 10 can sink into the threaded hole to be detected, it indicates that the threaded hole is qualified: on one hand, the screw can be screwed in smoothly; on the other hand, the number of turns of the threaded hole also meets the requirement. Conversely, if the thread detection part 10 cannot completely sink into the threaded hole to be detected, it indicates that the threaded hole is unqualified: on one hand, the screw cannot be screwed in smoothly; on the other hand, the number of turns of the threaded hole also fails to meet the requirement.
[0025] When using the utility model for threaded hole detection, an electric screwdriver is used instead of manual screwing to perform full inspection on the threaded holes. The tightening torque for screw assembly of MIM parts is 1.5N.m. The necessary conditions for no abnormality in assembly after full inspection of MIM parts with screws are: 1. The torque of the electric screwdriver 1 for full inspection is far less than the assembly torque; 2. The torque of the electric screwdriver 1 for full inspection is the same as that of manual screwing.
[0026] Tests show that the torque of manual screwing during manual full inspection is 0.01~0.03N.m, therefore the torque of the electric screwdriver 1 selected for full inspection should be 0.01~0.03N.m, and the maximum force applied by the electric screwdriver 1 to the screw is 0.03N.m. A half-threaded screw 5 is used instead of a full-threaded screw, and the number of thread turns of the half-threaded screw 5 is fixed at 10 turns according to product requirements. When the electric screwdriver 1 applies the maximum force to the screw, if all threads of the half-threaded screw 5 sink into the threaded hole, the inspection is qualified; if all threads of the half-threaded screw 5 do not sink into the threaded hole, the inspection is unqualified. During full inspection of threaded holes, one half-threaded screw 5 is used to inspect about 200 threaded holes, and quick disassembly and replacement are carried out after inspecting 200 threaded holes.
[0027] Currently, some automated equipment exists on the market that uses servo motors and torque sensors to control torque and speed, and displacement sensors to control screw feed to determine the effective number of thread turns. However, such equipment requires a high investment, often costing hundreds of thousands of yuan, failing to achieve the goal of cost reduction. Others use electric thread gauges for full inspection, but these require custom-made gauges, each costing hundreds of yuan—hundreds of times the price of the half-thread screw 5 in this device. The cost per MIM part is too high, still failing to reduce costs. This device, however, utilizes a quick-release connection structure between the bit 2 and the half-thread screw 5, enabling rapid installation and removal of the screw. Simultaneously, it employs a low-torque electric screwdriver 1 in conjunction with the screw 5, achieving low-investment, low-cost, and high-precision thread count detection for full inspection of threaded holes.
Claims
1. A rapid full inspection device for threaded holes in MIM parts, comprising an electric screwdriver (1) and a bit (2) mounted on the electric screwdriver (1), characterized in that: The bit (2) is sequentially connected to a hollow set screw (3), a screw sleeve (4), and a half-thread screw (5). The hollow set screw (3) has a through hole coaxially machined inside, and an external thread is machined on the outer wall of the hollow set screw (3). The screw sleeve (4) has a blind hole coaxially machined inside, and an internal thread matching the external thread of the hollow set screw (3) is machined on the upper side wall of the blind hole. A rectangular opening (6) is machined on the lower side wall of the blind hole, and a U-shaped opening with the same orientation as the rectangular opening (6) is machined on the screw sleeve (4) at the bottom of the blind hole. 7) The semi-threaded screw (5) includes a bolt head (8), a smooth shank (9) and a thread detection part (10) connected in sequence. The bolt head (8) has a non-circular groove that matches the working end of the bit (2). The bit (2) is fixedly installed in the through hole of the hollow set screw (3). The hollow set screw (3) is screwed into the blind hole through the thread. The semi-threaded screw (5) is installed at the bottom of the screw sleeve (4) through a rectangular opening (6) and a U-shaped opening (7). The working end of the bit (2) extends into the non-circular groove of the bolt head (8).
2. The rapid full inspection device for threaded holes of MIM parts according to claim 1, characterized in that: The screwdriver bit (2) is fixed to the through hole of the hollow set screw (3) by an interference fit.
3. The rapid full inspection device for threaded holes of MIM parts according to claim 1, characterized in that: The working end of the bit (2) is hexagonal, and the cross-section of the non-circular groove of the bolt head (8) is hexagonal.
4. The rapid full inspection device for threaded holes of MIM parts according to claim 1, characterized in that: The end of the U-shaped opening (7) is semi-circular, and the semi-circular part is coaxial with the screw sleeve (4). The radius of the semi-circular part is the same as the radius of the smooth rod part (9).
5. A rapid full inspection device for threaded holes in MIM parts according to claim 1, characterized in that: The bit (2) is stepped from large to small along the drive end to the working end, and the hollow set screw (3) is installed on the step near the working end.
6. A rapid full inspection device for threaded holes in MIM parts according to claim 1, characterized in that: The outer wall of the screw sleeve (4) is provided with an anti-slip block (11).