Machining method for directly connecting zinc sulfide balls through low-temperature brazing for tool design

Abstract

The invention discloses a machining method for directly connecting a zinc sulfide ball device through low-temperature brazing for tool design, relates to the technical field of low-temperature brazing connection, and discloses a method for brazing a zinc sulfide ball cover through low temperature, and the method specifically comprises the following steps that S1, base metal preparation is conducted, specifically, the to-be-welded face of a boss of the ball cover is polished through 60-mesh raw abrasive paper till the surface roughness is Ra6.3, and the surface roughness is Ra6.3; performing ultrasonic treatment in acetone for 25 to 30 minutes; s2, brazing filler metal is prepared, specifically, a certain amount of glass brazing filler metal powder and terpilenol are mixed according to the proportion of 49-50: 1-1.1 and stirred to be uniform, and pasty brazing filler metal with a certain viscosity is obtained. According to the machining method for directly connecting the zinc sulfide ball device through low-temperature brazing for tool design, the ball cover and the tool interact with the paste brazing filler metal at the temperature of 200-300 DEG C, so that the end face of the ball cover and the tool possibly generate chemical or physical reaction, brazing filler metal particles are tightly connected after being in contact and diffusion, and the service life of the ball cover and the tool is prolonged. And then low-temperature brazing is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of low-temperature brazing connection, and in particular to a processing method for directly connecting zinc sulfide balls by low-temperature brazing in tooling design. Background Art

[0002] ZnS has the characteristics of high infrared transmittance and wide wave transmission range, and is currently the most widely used full-band infrared window material. The traditional optical window manufacturing process is to connect ZnS to the metal frame in the form of mechanical connection or bonding. This experiment uses low-temperature glass brazing filler to fill the structural parts and directly braze the ball cover after sintering.

[0003] In the counter-patent application with publication (announcement) number: CN118060789A, publication (announcement) date: 2024-05-24, and titled "A method for brazing zinc sulfide ceramics and titanium alloys using silver-based medium-temperature solder", a new AgGe eutectic solder is used to achieve medium-temperature vacuum sealing of zinc sulfide ceramics and titanium alloys at 680°C to 740°C. The solder has excellent wettability to both zinc sulfide ceramics and titanium alloys, and can achieve defect-free connection of zinc sulfide ceramics and titanium alloys, thereby improving the reliability of zinc sulfide ceramic and titanium alloy joints at higher temperatures of 500°C to 600°C, greatly expanding the application of zinc sulfide ceramics in the infrared window field.

[0004] In the prior art including the above patents, ZnS has high mechanical strength, stable chemical properties, and a relatively moderate thermal expansion coefficient. The main reason is that ZnS has a wide transmission band range. It covers the entire band from 0.35-14.5μm from visible light to far infrared, which means that advanced multi-band photoelectric detection systems can share a window to work. Since the directly prepared ZnS has certain size and shape limitations, it is necessary to connect the flat ZnS in the application of large-sized aircraft fairings and special complex infrared windows. At present, the optical window connection process at home and abroad is to connect multiple pieces of ZnS to the metal frame of titanium alloy by mechanical clamping or bonding. The strength of the mechanical connection form is not high, and the adhesive will age and fail under long-term use. The main problem is that the thickness of the large-sized ZnS optical window is large, resulting in a large thickness of the metal frame, forming a light blocking effect on the optical system, weakening the signal receiving ability, and thus reducing the performance of the photoelectric tracking system. Moreover, the airtightness and strength of the mechanical assembly are also lower than those of welding. Therefore, it is necessary to overcome the problem of light blocking effect of traditional splicing process on infrared detection system, improve system performance and meet the use requirements of various models. Therefore, the research on ZnS connection technology is particularly important.

[0005] Faced with the requirement to further improve the performance of infrared detection and infrared guidance systems of fighter jets, missiles and other flying weapons, it is necessary to improve the manufacturing process of infrared window structural components, use welding instead of mechanical clamping and bonding, remove metal frames, reduce the obstruction of structural parts to infrared signal detectors, and improve the strength and service life of the light window and the performance of the entire infrared detection system.

[0006] In practical applications, in order to further increase the infrared transmittance of ZnS and protect the film surface from scratches, a layer or even multiple layers of anti-reflection films are coated on the light-transmitting surface of ZnS. The film materials include Al 2 O 3 、TiO 2 , YF 3 , diamond-like carbon (DLC), etc. This series of antireflection films may produce defects such as peeling, delamination, cracks and bubbles under high temperature heating conditions. Summary of the invention

[0007] The purpose of the present invention is to provide a processing method for directly connecting zinc sulfide balls by low temperature brazing in tooling design to solve the above-mentioned shortcomings in the prior art.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] A method for low temperature brazing of a zinc sulfide ball cover, the method specifically comprising the following steps:

[0010] S1 Preparation of base material: Grind the welding surface of the boss of the ball cover with 60-grit coarse sandpaper to a surface roughness of Ra6.3, and perform ultrasonic treatment in acetone for 25-30 minutes;

[0011] S2 solder preparation: Mix a certain amount of glass solder powder and pine alcohol in a ratio of 49-50:1 -1.1, and stir evenly to obtain a paste solder with a certain viscosity.

[0012] S3 solder coating: paste solder is coated on the surface of the ball cover to be welded by screen printing, so that the surface of the base material is evenly covered with a layer of paste solder with a thickness of 49.9-50.1μm.

[0013] S4 Drying: Place the ball cover coated with solder in a constant temperature drying oven and dry it at 200-300℃ for 55-65min to fully volatilize the pine oil and soften the paste solder to have a certain fluidity and viscosity, so that the end face of the ball cover and the tooling may undergo chemical or physical reaction, and the solder particles can be closely connected after contact and diffusion;

[0014] S5 sintering: the base material covered with the powdered solder is placed in an air furnace and heated to 400-450°C at a heating rate of 5°C / min, kept at this temperature for 10-60 minutes, and cooled to room temperature along with the furnace, so that a uniform layer of glass solder is sintered on the surface of the ball cover to be welded;

[0015] S6: Assemble the ball cover processed in step S5 and the brazing tooling;

[0016] S7 brazing: Place the assembled joint in an air furnace and heat it to 400-450°C at a heating rate of 5°C / min, keep it warm for 10-60 minutes, and cool it to room temperature with the furnace to obtain a brazed joint.

[0017] Preferably, the concentrations of acetone and terpineol are both greater than 99%.

[0018] Preferably, the glass solder powder in step S2 is K9 visible light glass.

[0019] A zinc sulfide ball cover for tooling design comprises a base, a connecting ring and a ball cover.

[0020] Preferably, the ball cover has a diameter of 156 mm, a center thickness of 48.3 mm, and a radius of 90 mm.

[0021] Preferably, a vent hole is provided at the bottom of the base to facilitate vacuuming and measuring the overall air tightness after the ball cover is installed.

[0022] Preferably, the base and the circumferential side of the connecting ring are respectively provided with thread grooves, thread gaps or back-off grooves, so that the connecting ring and the base can fit together.

[0023] Preferably, a small platform is provided on the peripheral side of the outer wall of the base to facilitate the placement of the ball cover and play a fixing role.

[0024] Preferably, the inner and outer edges of the connecting ring are designed to be arc-shaped, and the arc angle thereof is the same as the arc angle of the ball cover, so as to facilitate fitting with the ball cover.

[0025] Preferably, a gap of 0.1 mm is left between the connecting ring and the outer edge of the ball cover to facilitate the filling of the solder. Under low-temperature soldering, the surplus is sufficient to be completely integrated to form a tight connection.

[0026] Preferably, the base and the connecting ring are both made of 7075 aluminum.

[0027] In the above technical scheme, the present invention provides a processing method for directly connecting a zinc sulfide ball with a tool design by low-temperature brazing. The ball cover and the tool interact with the paste solder at a temperature of 200-300°C, so that a chemical or physical reaction may occur between the end face of the ball cover and the tool, so that the solder particles are in contact and diffused to form a tight connection, thereby achieving low-temperature brazing.

[0028] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

[0029] This application document provides an overview of various implementations or examples of the technology described in the present disclosure, and is not a comprehensive disclosure of the entire scope or all features of the disclosed technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0031] Figure 1 A schematic diagram of the assembly structure of the tooling provided in an embodiment of the present invention;

[0032] Figure 2 A schematic diagram of a base structure provided in an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the ball cover structure provided by an embodiment of the present invention.

[0034] Description of reference numerals:

[0035] 1. Base; 2. Connecting ring; 3. Ball cover. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0037] First, the chemical or physical reaction that may occur in step S4 of the present application is explained: since the base 1 and the connecting ring 2 are both made of 7075 aluminum, and aluminum is prone to undergo a slow oxidation reaction in the air to generate aluminum oxide, in step S4, when zinc sulfide and aluminum oxide are heated together, the oxidation reaction of zinc sulfide releases sulfur dioxide and oxygen, and aluminum oxide may provide the oxygen source required for the reaction (although it is not easy to decompose itself), which may promote the oxidation reaction of zinc sulfide. At the same time, there may be some physical interactions between zinc sulfide and aluminum oxide, such as contact and diffusion between particles, which may also affect the reaction.

[0038] However, it is important to note that although zinc sulfide and aluminum oxide may interact when heated, this does not mean that they will directly react chemically to form new compounds. In fact, it is more likely that they will react separately (such as oxidation of zinc sulfide) or just physically mix.

[0039] In general, zinc sulfide and aluminum oxide may interact with each other when heated, but the specific reaction depends on many factors and a direct chemical reaction may not necessarily occur.

[0040] Embodiment 1:

[0041] A method for low temperature brazing of a zinc sulfide ball cover, the method specifically comprising the following steps:

[0042] S1. Preparation of base material: The boss surface of the ball cover 3 to be welded is polished with 60-grit coarse sandpaper to a surface roughness of Ra6.3, and then subjected to ultrasonic treatment in acetone for 25 minutes, wherein the concentration of acetone is greater than 99%.

[0043] S2 solder preparation: a certain amount of glass solder powder and pineol are mixed in a ratio of 49:1, and stirred evenly to obtain a paste solder with a certain viscosity, wherein the glass solder powder is K9 visible light glass, and the concentration of pineol is greater than 99%.

[0044] S3 solder coating: paste solder is coated on the surface to be welded of the ball cover 3 by screen printing, so that the surface of the base material is evenly covered with a layer of paste solder with a thickness of 49.9 μm.

[0045] S4 Drying: Place the ball cover 3 coated with solder in a constant temperature drying oven and dry it at 200°C for 55 minutes to fully volatilize the pine oil, soften the paste solder, and have a certain fluidity and viscosity, so that the end face of the ball cover 3 and the tooling may undergo a chemical or physical reaction, and the solder particles are closely connected after contact and diffusion; wherein the concentration of pine oil is greater than 99%.

[0046] S5 sintering: the base material covered with the powdered solder is placed in an air furnace and heated to 400°C at a heating rate of 5°C / min, kept warm for 20 minutes, and cooled to room temperature in the furnace, so that a uniform layer of glass solder is sintered on the surface to be welded of the ball cover 3.

[0047] S6: Assemble the ball cover 3 processed in step S5 with the brazing tooling. Figure 1 shown.

[0048] S7 brazing: Place the assembled joint in an air furnace and heat it to 400°C at a heating rate of 5°C / min, keep it warm for 20 min, and cool it to room temperature with the furnace to obtain a brazed joint.

[0049] A tool for low temperature brazing of a zinc sulfide ball cover 3, comprising a base 1, a connecting ring 2 and a ball cover 3,

[0050] This tooling can not only weld ZnS polished and coated ball covers, but also braze conductive ball covers.

[0051] The diameter of the ball cover 3 is 156 mm, the center thickness is 48.3 mm, and the radius is 90 mm.

[0052] A vent hole is provided at the bottom of the base 1 to facilitate vacuuming and measuring the overall air tightness after the ball cover 3 is installed.

[0053] The base 1 and the connecting ring 2 are respectively provided with thread grooves, thread gaps or back-off grooves on their circumferences, so that the connecting ring 2 and the base 1 can fit together.

[0054] A small platform is arranged on the peripheral side of the outer wall of the base 1 to facilitate the placement of the ball cover 3 and play a fixing role.

[0055] The inner and outer edges of the connecting ring 2 are designed to be arc-shaped, and the arc angle thereof is the same as the arc angle of the ball cover 3 , so as to facilitate fitting with the ball cover 3 .

[0056] Among them, a gap of 0.1mm is left between the connecting ring 2 and the outer edge of the ball cover 3 to facilitate the filling of the solder, and a small amount of pine oil can be added to the solder to increase the viscosity so as to better complete the solder filling, reduce the pores at the joint, and increase the welding strength. Under low-temperature brazing, the surplus is sufficient to be completely integrated to form a tight connection.

[0057] Wherein, the base 1 and the connecting ring 2 are both made of 7075 aluminum.

[0058] Embodiment 2:

[0059] A method for low temperature brazing of a zinc sulfide ball cover, the method specifically comprising the following steps:

[0060] S1. Preparation of base material: The boss surface of the ball cover 3 to be welded is polished with 60-grit coarse sandpaper to a surface roughness of Ra6.3, and then subjected to ultrasonic treatment in acetone for 27 minutes, wherein the concentration of acetone is greater than 99%.

[0061] S2 solder preparation: a certain amount of glass solder powder and pineol are mixed in a ratio of 49.5:1.05, and stirred evenly to obtain a paste solder with a certain viscosity, wherein the glass solder powder is K9 visible light glass, and the concentration of pineol is greater than 99%.

[0062] S3 solder coating: paste solder is coated on the surface to be welded of the ball cover 3 by screen printing, so that the surface of the base material is evenly covered with a layer of paste solder with a thickness of 50 μm.

[0063] S4 drying: placing the ball cover 3 coated with solder in a constant temperature drying oven and drying at 200°C for 50 minutes to fully volatilize the pine oil, soften the paste solder, and have a certain fluidity and viscosity, so that the end face of the ball cover 3 and the tooling may undergo a chemical or physical reaction, and the solder particles are closely connected after contact and diffusion; wherein the concentration of pine oil is greater than 99%.

[0064] S5 sintering: The base material covered with the powdered solder is placed in an air furnace and heated to 425°C at a heating rate of 5°C / min, kept at this temperature for 30 minutes, and cooled to room temperature with the furnace, so that a uniform layer of glass solder is sintered on the surface to be welded of the ball cover 3; ZnS is brazed at 425°C for 30 minutes. When brazing is performed by sintering and remelting, the thickness of the interface reaction layer gradually increases with the increase in temperature, because the increase in temperature will promote the diffusion of the S element into the glass solder, reduce the viscosity of the glass solder, and increase the fluidity of the glass solder.

[0065] S6: Assemble the ball cover 3 processed in step S5 with the brazing tooling. Figure 1 shown.

[0066] S7 brazing: The assembled joint was placed in an air furnace and heated to 425°C at a heating rate of 5°C / min, kept warm for 30 min, and cooled to room temperature with the furnace to obtain a brazed joint.

[0067] A tool for low temperature brazing of a zinc sulfide ball cover 3, comprising a base 1, a connecting ring 2 and a ball cover 3,

[0068] This tooling can not only weld ZnS polished and coated ball covers, but also braze conductive ball covers.

[0069] The diameter of the ball cover 3 is 156 mm, the center thickness is 48.3 mm, and the radius is 90 mm.

[0070] A vent hole is provided at the bottom of the base 1 to facilitate vacuuming and measuring the overall air tightness after the ball cover 3 is installed.

[0071] The base 1 and the connecting ring 2 are respectively provided with thread grooves, thread gaps or back-off grooves on their circumferences, so that the connecting ring 2 and the base 1 can fit together.

[0072] A small platform is arranged on the peripheral side of the outer wall of the base 1 to facilitate the placement of the ball cover 3 and play a fixing role.

[0073] The inner and outer edges of the connecting ring 2 are designed to be arc-shaped, and the arc angle thereof is the same as the arc angle of the ball cover 3 , so as to facilitate fitting with the ball cover 3 .

[0074] Among them, a gap of 0.1mm is left between the connecting ring 2 and the outer edge of the ball cover 3 to facilitate the filling of the solder, and a small amount of pine oil can be added to the solder to increase the viscosity so as to better complete the solder filling, reduce the pores at the joint, and increase the welding strength. Under low-temperature brazing, the surplus is sufficient to be completely integrated to form a tight connection.

[0075] Wherein, the base 1 and the connecting ring 2 are both made of 7075 aluminum.

[0076] Embodiment three:

[0077] A method for low temperature brazing of a zinc sulfide ball cover, the method specifically comprising the following steps:

[0078] S1. Preparation of base material: The boss surface of the ball cover 3 to be welded is polished with 60-mesh coarse sandpaper to a surface roughness of Ra6.3, and then subjected to ultrasonic treatment in acetone for 30 minutes, wherein the concentration of acetone is greater than 99%.

[0079] S2 solder preparation: a certain amount of glass solder powder and pineol are mixed in a ratio of 50:1.1, and stirred evenly to obtain a paste solder with a certain viscosity, wherein the glass solder powder is K9 visible light glass, and the concentration of pineol is greater than 99%.

[0080] S3 solder coating: paste solder is coated on the surface to be welded of the ball cover 3 by screen printing, so that the surface of the base material is evenly covered with a layer of paste solder with a thickness of 50.1 μm.

[0081] S4 Drying: Place the ball cover 3 coated with solder in a constant temperature drying oven and dry it at 300°C for 65 minutes to fully volatilize the pine oil, soften the paste solder, and have a certain fluidity and viscosity, so that the end face of the ball cover 3 and the tooling may undergo a chemical or physical reaction, and the solder particles are in contact and diffused to form a tight connection; wherein the concentration of pine oil is greater than 99%.

[0082] S5 sintering: The base material covered with the powdered solder is placed in an air furnace and heated to 450°C at a heating rate of 5°C / min, kept at this temperature for 60 minutes, and cooled to room temperature with the furnace, so that a uniform layer of glass solder is sintered on the surface to be welded of the ball cover 3; ZnS is brazed at 450°C for 60 minutes. When brazing is performed by sintering and remelting, the thickness of the interface reaction layer gradually increases with the increase in temperature, because the increase in temperature will promote the diffusion of the S element into the glass solder, reduce the viscosity of the glass solder, and increase the fluidity of the glass solder.

[0083] S6: Assemble the ball cover 3 processed in step S5 with the brazing tooling. Figure 1 shown.

[0084] S7 brazing: The assembled joint was placed in an air furnace and heated to 450°C at a heating rate of 5°C / min, kept warm for 60 min, and cooled to room temperature with the furnace to obtain a brazed joint.

[0085] A tool for low temperature brazing of a zinc sulfide ball cover 3, comprising a base 1, a connecting ring 2 and a ball cover 3,

[0086] This tooling can not only weld ZnS polished and coated ball covers, but also braze conductive ball covers.

[0087] The diameter of the ball cover 3 is 156 mm, the center thickness is 48.3 mm, and the radius is 90 mm.

[0088] A vent hole is provided at the bottom of the base 1 to facilitate vacuuming and measuring the overall air tightness after the ball cover 3 is installed.

[0089] The base 1 and the connecting ring 2 are respectively provided with thread grooves, thread gaps or back-off grooves on their circumferences, so that the connecting ring 2 and the base 1 can fit together.

[0090] A small platform is arranged on the peripheral side of the outer wall of the base 1 to facilitate the placement of the ball cover 3 and play a fixing role.

[0091] The inner and outer edges of the connecting ring 2 are designed to be arc-shaped, and the arc angle thereof is the same as the arc angle of the ball cover 3 , so as to facilitate fitting with the ball cover 3 .

[0092] Among them, a gap of 0.1mm is left between the connecting ring 2 and the outer edge of the ball cover 3 to facilitate the filling of the solder, and a small amount of pine oil can be added to the solder to increase the viscosity so as to better complete the solder filling, reduce the pores at the joint, and increase the welding strength. Under low-temperature brazing, the surplus is sufficient to be completely integrated to form a tight connection.

[0093] Wherein, the base 1 and the connecting ring 2 are both made of 7075 aluminum.

[0094] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for low temperature brazing of zinc sulfide ball cover, characterized in that: The method specifically comprises the following steps: S1 Preparation of base material: Grind the welding surface of the boss of the ball cover with 60-grit coarse sandpaper to a surface roughness of Ra6.3, and perform ultrasonic treatment in acetone for 25-30 minutes; S2 solder preparation: Mix a certain amount of glass solder powder and pine alcohol in a ratio of 49-50:1-1.1, and stir evenly to obtain a paste solder with a certain viscosity. S3 solder coating: paste solder is coated on the surface of the ball cover to be welded by screen printing, so that the surface of the base material is evenly covered with a layer of paste solder with a thickness of 49.9-50.1μm. S4 Drying: Place the ball cover coated with solder in a constant temperature drying oven and dry it at 200-300℃ for 55-65min to fully volatilize the pine oil and soften the paste solder to have a certain fluidity and viscosity, so that the end face of the ball cover and the tooling may undergo chemical or physical reaction, and the solder particles can be closely connected after contact and diffusion; S5 sintering: the base material covered with the powdered solder is placed in an air furnace and heated to 400-450°C at a heating rate of 5°C / min, kept at this temperature for 10-60 minutes, and cooled to room temperature along with the furnace, so that a uniform layer of glass solder is sintered on the surface of the ball cover to be welded; S6: Assemble the ball cover processed in step S5 and the brazing tooling; S7 brazing: Place the assembled joint in an air furnace and heat it to 400-450°C at a heating rate of 5°C / min, keep it warm for 10-60 minutes, and cool it to room temperature with the furnace to obtain a brazed joint.

2. The method for low temperature brazing of zinc sulfide spherical cap according to claim 1, characterized in that: The concentrations of the acetone and terpineol are both greater than 99%.

3. The method for low temperature brazing of zinc sulfide spherical cap according to claim 1, characterized in that: The glass solder powder in step S2 is K9 visible light glass.

4. A zinc sulfide ball cover for tooling design, which is used to process the method of low temperature brazing of zinc sulfide ball cover according to any one of claims 1 to 3, characterized in that: It comprises a base (1), a connecting ring (2) and a ball cover (3).

5. The zinc sulfide ball cover for tooling design according to claim 4, characterized in that: The ball cover (3) has a diameter of 156 mm, a center thickness of 48.3 mm, and a radius of 90 mm.

6. The zinc sulfide ball cover for tooling design according to claim 4, characterized in that: A vent hole is provided at the bottom of the base (1). After the ball cover (3) is installed, vacuum is drawn to measure the overall air tightness.

7. The zinc sulfide ball cover for tooling design according to claim 4, characterized in that: The base (1) and the connecting ring (2) are respectively provided with thread grooves, thread gaps or cutter recesses on their circumferential sides, so that the connecting ring (2) and the base (1) can fit together.

8. The zinc sulfide ball cover for tooling design according to claim 4, characterized in that: A small platform is provided on the peripheral side of the outer wall of the base (1) to facilitate the placement of the ball cover (3) and to play a fixing role.

9. The zinc sulfide ball cover for tooling design according to claim 4, characterized in that: The inner and outer edges of the connecting ring (2) are designed to be arc-shaped, and the arc angle is the same as the arc angle of the ball cover (3), so as to facilitate fitting with the ball cover (3).

10. The zinc sulfide ball cover for tooling design according to claim 4, characterized in that: A gap of 0.1 mm is left between the connecting ring (2) and the outer edge of the ball cover (3).

11. The zinc sulfide ball cover for tooling design according to claim 4, characterized in that: The base (1) and the connecting ring (2) are both made of 7075 aluminum.

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