Watch Accessories MIM Parts

Product Introduction

Production Method
A manufacturing method for the production process of a high-precision special-shaped structure Watch Accessories MIM Parts hook

【Technical field】
The invention belongs to the technical field of connectors, in particular to a production process of a high-precision special-shaped structural metal injection watch accessory hook.

【Background technique】
Watch Accessories MIM Parts process is suitable for mass production of products with complex shapes and high precision. Some products have complex structures (such as internal undercuts, screw holes, etc.), the mold cannot be fully formed, and the parts that cannot be formed must be processed by post-processing (such as: cnc). Post-processing will cause secondary processing tolerances and high costs. The size of some products is too small, resulting in the post-process can not be realized.
At present, there is a hook part of a watch accessory. The step accuracy of the hook is required to be controlled within 0.01mm. The injection molding process and sintering process in the prior art are used. Due to the unstable injection pressure of the injection molding itself, the injection The dimensional accuracy of the formed product itself is prone to fluctuations, and it is impossible to guarantee that each product in the same batch meets the accuracy requirements; in addition, in the sintering process, there are many uncertain factors, which seriously affect the compactness of the product and are prone to deformation Dimensional instability or product strength cannot meet the requirements.
Therefore, need to provide a kind of production technology of new high-precision special-shaped structure metal injection watch accessories buckle to solve the above problems.

【Technical Realization Elements】
The main purpose of the Watch Accessories MIM Parts of the present invention is to provide a high-precision special-shaped structure metal injection watch accessories hook production process, which realizes the molding of complex and precise structures, and the product accuracy can be controlled within 0.01mm, and the product size is more stable .
The present invention realizes above-mentioned purpose through following technical scheme: a kind of high-precision special-shaped structure metal injection watch accessories hook production process, it comprises the following steps:
Injection molding: use the injection molding process to form the hook blank on the injection machine;
Product classification: use the pressure monitoring curve diagram of each mold injection process in the injection machine to analyze the fluctuation rate of the pressure monitoring curve diagram, and inject the hook blank from the corresponding mold whose fluctuation rate exceeds the set value items removed;

Degreasing and sintering:
Put the hook blank that meets the set fluctuation rate into the carrier, and then put the carrier into the sintering furnace;
Negative pressure degreasing:
Evenly raise the temperature of the sintering furnace to 230-250°C within 75-85 minutes, maintain the temperature for 45-55 minutes, and at the same time pass nitrogen protection into the sintering furnace, and control the flow rate at 38-42l/min;
The sintering furnace continues to uniformly heat up to 370-390°C within 90-110 minutes, maintain the temperature for 55-65 minutes, and maintain nitrogen protection;
The sintering furnace continues to uniformly heat up to 470-490°C within 65-75 minutes, maintain the temperature for 55-65 minutes, and maintain nitrogen protection;
The sintering furnace continues to uniformly heat up to 590-610°C within 55-65 minutes, and maintains the temperature for 85-95 minutes, and maintains nitrogen protection;
The sintering furnace continues to uniformly heat up to 690-710°C within 60 minutes, and maintains the temperature for 30 minutes, and maintains nitrogen protection;
The sintering furnace continues to heat up uniformly to 790-810°C within 35-45 minutes, and maintain nitrogen protection during the heating process;

Vacuum internal combustion:
Keep the temperature in the sintering furnace at 790-810°C, keep it warm for 25-35 minutes, and stop the nitrogen input at the same time;
The sintering furnace continues to uniformly heat up to 1090-1110°C within 65-75 minutes, and maintain this temperature for 55-65 minutes;

Partial pressure sintering:
Continue to raise the temperature of the sintering furnace evenly to 1275-1295°C within 110-130 minutes, pressurize the sintering furnace at the same time, keep the pressure at 10-12kpa, and input argon protection, and control the flow rate at 38-42l/min ;
Keep the temperature of the sintering furnace at 1275-1295°C and keep it warm for 170-190 minutes;
The temperature of the sintering furnace is uniformly lowered to 790-810°C within 110-130 minutes, and the input of argon gas and the pressure value in the furnace are maintained;
Forced cooling: Cool the sintering furnace to 60°C within 55-65 minutes, and raise the pressure in the furnace to 84-88kpa.
Further, the carrier includes a bottom plate, a surrounding baffle plate arranged on the bottom plate and enclosing to form an accommodating space, a carrier plate arranged in the accommodating space and carrying the hook blank, And a cover plate that covers the surrounding baffle plate and closes the accommodating space.
Further, the sintering furnace includes a cylindrical outer cylinder as a whole, an insulation cylinder arranged in the outer cylinder, a bearing bracket arranged in the inner space of the insulation cylinder, located in the insulation cylinder and surrounding A plurality of heating modules distributed on the bearing bracket and a sealing control door for sealing the outer cylinder, the heating modules are distributed along the axial direction of the heat preservation cylinder.
Further, several layers of support units are arranged on the support bracket, and one carrier is inserted into each layer of support units.
Compared with the existing technology, the beneficial effect of the production process of a high-precision special-shaped structural metal injection watch accessory hook of the present invention is that: the high-precision injection molding mold is used for injection molding, which ensures the realization of complex structures and replaces existing extrusion Pressing, wire cutting and other processing procedures reduce the process steps and improve production efficiency; by using the pressure change monitoring curve of the injection machine to classify and screen the products after injection molding, the fluctuation rate of the pressure change monitoring curve is selected in the design Formed products within a certain range enter the subsequent production process, laying an important foundation for the realization of high-precision products; by adopting high-precision sintering technology, designing a carrier with enclosures and cover plates to carry products into the sintering furnace, greatly reducing It eliminates the risk of product contamination during the sintering process and provides a guarantee for maintaining the dimensional stability of the product during the sintering process; through the high-temperature design and duration design of the degreasing stage and sintering stage, the control ability of product compactness and product quality is improved, making Product dimensions are more stable, enabling high-precision production.

【Description of drawings】
FIG. 1 is a schematic structural diagram of a carrier according to an embodiment of the present invention;
Fig. 2 is a schematic top view of the carrier with the cover plate removed in the embodiment of the present invention;
Figure 3 is a schematic cross-sectional structure diagram of a sintering furnace in an embodiment of the present invention;
The numbers in the figure indicate:
1-vehicle, 11-base plate, 12-accommodating space, 13-surrounding baffle, 14-carrier plate, 15-cover plate;
2-Sintering furnace, 21-Outer cylinder, 22-Insulation cylinder, 23-Loading support, 24-Heating module, 25-Sealing control door.

【Detailed ways】
Embodiment 1:
Please refer to Fig. 1-Fig. 3. This embodiment is a production process of a high-precision special-shaped structural metal injection watch accessory hook, which includes the following steps:
1) Injection molding: Put the raw materials into the high-precision injection machine, and use the injection molding process to form the hook blank;
2) Product classification: use the pressure monitoring curve diagram of each mold injection process in the high-precision injection machine to analyze the fluctuation rate of the pressure monitoring curve diagram, and inject hook blanks from a mold whose fluctuation rate exceeds the set value items removed;
Through the precise monitoring of pressure injection parameters, the pressure of the products entering the subsequent process is guaranteed to be stable during injection molding, which reduces the fluctuation of the products, improves the stability of injection, and ensures that the dimensional accuracy is controlled within the range of 0.005mm;
3) Degreasing and sintering:
Put the hook blank that meets the set fluctuation rate into the carrier 1, and then put the carrier 1 into the sintering furnace 2; in order to reduce the risk of product contamination during the sintering process, the The carrier 1 includes a base plate 11, a surrounding baffle plate 13 arranged on the base plate 11 and enclosing and forming an accommodating space 12, a carrier plate 14 arranged in the accommodating space 12 and carrying the hook blank, and a cover closed on the Surrounding the baffle plate 13 and the cover plate 15 that closes the accommodation space 12; in order to improve the uniform heating of the product in the sintering process, the present embodiment adopts a special furnace structure design. Specifically, the sintering furnace 2 includes a cylindrical body as a whole. The outer cylinder 21, the insulation cylinder 22 arranged in the outer cylinder 21, the bearing bracket 23 arranged in the inner space of the insulation cylinder 22, a number of heating modules 24 located in the insulation cylinder 22 and distributed around the bearing bracket 23, and the seal for sealing the outer cylinder 21 The control door 25 and the heating module 24 are axially distributed along the heat preservation tube 22; several layers of support units are arranged on the support bracket 23, and a carrier is inserted and placed on the support unit of each layer;

Negative pressure degreasing:
Raise the temperature of the sintering furnace 2 to 240°C uniformly within 80 minutes, and maintain the temperature for 50 minutes. At the same time, nitrogen protection is introduced into the sintering furnace, the flow rate is controlled at 40l/min, and the pressure is controlled at 0kpa;
The sintering furnace 2 continues to uniformly heat up to 380°C within 100 minutes, maintains the temperature for 60 minutes, and maintains nitrogen protection;
The sintering furnace 2 continues to uniformly heat up to 480°C within 70 minutes, maintains the temperature for 60 minutes, and maintains nitrogen protection;
The sintering furnace 2 continues to uniformly heat up to 600°C within 60 minutes, maintains the temperature for 90 minutes, and maintains nitrogen protection;
Sintering furnace 2 continues to uniformly heat up to 700°C within 60 minutes, maintain this temperature for 30 minutes, and maintain nitrogen protection;
The sintering furnace 2 continues to uniformly heat up to 800°C within 40 minutes, and maintain nitrogen protection during the heating process;
In this embodiment, by prolonging the duration of the negative pressure degreasing stage, the product can be degreased more fully, and the control of carbon can be more stable when the degreasing is sufficient, so that the gap between the metal molecules at the sintered end of the product is uniform, reducing Intergranular impurities make the product more stable in density and strength, thus making the size more stable.

Vacuum internal combustion:
Keep the temperature in the sintering furnace 2 at 800°C, keep it warm for 30 minutes, stop nitrogen input at the same time, and keep the pressure in the furnace at 0kpa;
Sintering furnace 2 continues to uniformly heat up to 1100°C within 70 minutes, and maintains the temperature for 60 minutes;

Partial pressure sintering:
Continue to uniformly raise the temperature of sintering furnace 2 to 1285°C within 120 minutes, pressurize the interior of sintering furnace 2 at the same time, keep the pressure at 11kpa, and input argon protection, and control the flow rate at 40l/min;
Keep the temperature of sintering furnace 2 at 1285°C and keep it warm for 180 minutes;
The temperature of the sintering furnace 2 is uniformly lowered to 800°C within 120 minutes, and the input of argon gas and the pressure value in the furnace are maintained;
In this embodiment, the sintering temperature and sintering time are increased in the vacuum internal sintering stage and the partial pressure sintering stage, which can effectively control the deoxidation state and improve the compactness of the product, making the product size more temperature and maintaining a higher precision dimensional accuracy .
Forced cooling: Cool down the sintering furnace 2 to 60°C within 60 minutes, raise the pressure in the furnace to 86kpa, and keep the input of argon.
In this example, the hooks of watch accessories produced by the above-mentioned process were tested for density, size and hardness. Among them, the density was 7.68-7.72g/cm3, the hardness was 280-320hv, and the size fluctuation was 2 %.
Inside. From the above test results, it can be seen that the hook structure of watch accessories prepared in this example can effectively meet the customer's size requirements and performance requirements, and realize a production process with high precision and high dimensional stability.
The production process of the high-precision special-shaped structural metal injection watch accessory hook in this embodiment adopts high-precision injection molding mold injection molding, which ensures the realization of complex structures, replaces existing processing procedures such as extrusion and wire cutting, and reduces the number of process steps. , improve the production efficiency; by using the pressure change monitoring curve of the injection machine to classify and screen the products after injection molding, select the molded products whose fluctuation rate of the pressure change monitoring curve is within the set range to enter the subsequent production process, It has laid an important foundation for realizing the high-precision size of the product; through the use of high-precision sintering technology, the carrier with enclosure and cover plate is designed to carry the product into the sintering furnace, which greatly reduces the risk of product contamination during the sintering process. The stability of the product size during the sintering process provides a guarantee; through the high temperature design and time length design of the degreasing stage and the sintering stage, the control ability of product compactness and product quality is improved, the product size is more stable, and high-precision production can be realized.

Embodiment 2
The process steps of this embodiment are basically the same as those of Embodiment 1, the difference is that the temperature parameters, corresponding time parameters, pressure parameters and protective gas flow parameters in step 3) during the debinding and sintering process are slightly different, in order to show more clearly For the above-mentioned process, this embodiment adopts the form of a table to show the specific steps of step 3) degreasing and sintering, as shown in Table 1 for details.

Table 1
In this example, the hooks of watch accessories produced by the above-mentioned process were tested for density, size and hardness. Among them, the densitometer was 7.65-7.71g/cm3, the hardness was 282-318hv, and the size fluctuation was 2 %.
Inside. From the above test results, it can be seen that the hook structure of watch accessories prepared in this example can effectively meet the customer's size requirements and performance requirements, and realize a production process with high precision and high dimensional stability.
Embodiment three:
The process steps of this embodiment are basically the same as those of Embodiment 1, the difference is that the temperature parameters, corresponding time parameters, pressure parameters and protective gas flow parameters in step 3) during the degreasing and sintering process are slightly different, in order to show the above process more clearly process, this embodiment uses the form of a table to show the specific steps of step 3) degreasing and sintering, as shown in Table 2.

Table 2
In this example, the hooks of watch accessories produced by the above-mentioned process were tested for density, size and hardness. Among them, the densitometer was 7.65-7.71g/cm3, the hardness was 282-318hv, and the size fluctuation was 2 %.
Inside. From the above test results, it can be seen that the hook structure of watch accessories prepared in this example can effectively meet the customer's size requirements and performance requirements, and realize a production process with high precision and high dimensional stability.
What have been described above are only some embodiments of the present invention. For those of ordinary skill in the art, under the premise of not departing from the inventive concept of the present invention, some deformations and improvements can also be made, and these all belong to the protection scope of the present invention

Metal Injection Molding Process

Detection Systems