Machining method for grating-shaped mold part of pipe with double-layer structure

Abstract

The invention relates to the technical field of mold manufacturing, in particular to a machining method for a grating-shaped mold part of a double-layer structure pipe. The method comprises the steps that a blank comprising an auxiliary ring section, a cylinder section and a clamping section which are sequentially connected is obtained through cutting; the auxiliary ring section and the cylinder section are subjected to wire cutting machining to obtain a rough machining part; the rough machining part is fed into a high-temperature furnace to be heated for pre-hardening treatment; the rough machining part subjected to pre-hardening treatment is subjected to finish machining, and a finish machining part is obtained; the finish machining part is fed into a vacuum furnace to be subjected to vacuum quenching treatment; after the hoop claw inner plug is plugged into the cylinder section from the auxiliary ring section, the auxiliary ring section is cut off, and the cut finish machining part and the hoop claw inner plug are fed into a tempering furnace together to be subjected to tempering treatment; and the tempered finish machining part is subjected to polishing treatment. The technical problem that in the prior art, due to the fact that a grating part of a hollow-structure core mold is prone to being folded inwards and deformed due to losing of supporting in the machining process, the machined hollow-structure core mold is scrapped due to the fact that the size requirement is not met is effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of mold manufacturing, and particularly to a processing method for a grid-shaped mold part of a double-layer structure pipe. Background Art

[0002] A double-layer axially hollow pipe, also known as a double-layer axially hollow wall pipe, is usually composed of two layers of materials, with an axially hollow structure formed in the middle. This kind of pipe has inner and outer double-plane loading surfaces and working surfaces, and can make good use of mechanical principles to improve the strength and load-bearing capacity of the pipe. Double-layer axially hollow pipes are often applied to fields such as building drainage pipes, wire sheaths, and agricultural irrigation.

[0003] The processing of double-layer axially hollow pipes usually uses a special extrusion molding die to ensure the separation and molding of the inner and outer layers of the pipe, and to avoid adhesion of the inner and outer layers during the extrusion process, so as to form a double-layer axially hollow wall pipe with a complete cross-section. The extrusion molding die for double-layer axially hollow pipes mainly includes an outer guiding die, an inner fixing die, and a hollow structure core die. Among them, as Figure 1 shown, the hollow structure core die is a grid-shaped mold including a grid and a clamping end. When processing the hollow structure core die, it usually includes blanking (selecting appropriate metal materials according to the design drawing and using a sawing machine or a cutting machine for blanking), rough machining (using machine tools such as lathes and milling machines to perform rough machining on the blank, removing redundant materials, and initially forming the shape and contour of the core die), finish machining (using high-precision machine tools such as grinding machines or CNC machining centers to perform finish machining on the core die to ensure that the dimensional accuracy and shape accuracy of the core die meet the design requirements), heat treatment (performing heat treatment on the processed core die to improve its hardness and wear resistance), and surface treatment (performing surface treatment on the heat-treated core die, such as chrome plating and polishing, to improve its surface finish and corrosion resistance) in five steps.

[0004] However, the hollow structure core die is a single independent grid-shaped mold part, and the wall thickness of its grid part is relatively thin. When processing the hollow structure core die, after rough machining the grid structure, the grid structure is in a suspended state, resulting in the grid structure being prone to inward deformation due to loss of support during subsequent finish machining, heat treatment, and surface treatment, causing the size of the grid part of the processed hollow structure core die to shrink, and ultimately resulting in the scrapping of the processed hollow structure core die due to non-compliance with the size requirements. Summary of the Invention

[0005] The present invention provides a processing method for a grid-shaped mold part of a double-layer structure pipe to solve the technical problem that the grid part of the hollow structure core die in the prior art is prone to inward deformation due to loss of support during the processing, resulting in the scrapping of the processed hollow structure core die due to non-compliance with the size requirements.

[0006] In order to solve the above problems, the processing method of the grid-shaped mold parts of the double-layer structure pipe provided by the present invention adopts the following technical solutions:

[0007] A method for processing a grid-shaped mold part of a double-layer structure pipe comprises the following steps:

[0008] S1: blank cutting: cutting the raw material according to the design drawing to obtain a blank including an auxiliary ring segment, a cylindrical segment and a clamping segment connected in sequence, wherein the radial dimensions of the auxiliary ring segment and the clamping segment are both larger than the radial dimension of the cylindrical segment;

[0009] S2: Wire cutting rough machining: Use multiple cutters evenly spaced circumferentially on the ring blank to perform wire cutting on the auxiliary ring segment and the cylinder segment. The wire cutting path width is b1. During wire cutting, the cutter penetrates the thickness of the cylinder segment but does not penetrate the thickness of the auxiliary ring segment, dividing the cylinder segment into multiple grids arranged at intervals. After the wire cutting rough machining is completed, a rough machined part is obtained;

[0010] S3: Pre-hardening treatment: First, the rough-machined workpiece is sent into a high-temperature furnace for heating at a temperature of T1 and a holding time of t1, and then cooled to room temperature. After pre-hardening treatment, the hardness range of the rough-machined workpiece is HRC28-32°;

[0011] S4: Lathe finishing: First, the auxiliary ring segment of the rough-machined part after pre-hardening treatment is clamped on the lathe, and the outer peripheral surface, inner peripheral surface, end surface and outer extension part of the clamping segment are finished to the designed size; then, the auxiliary ring segment is loosened, the clamping segment is clamped on the lathe, and the outer peripheral surface and inner peripheral surface of the cylindrical segment grille are finished to the designed size to obtain a finished part;

[0012] S5: Vacuum quenching treatment: The finished parts are sent into a vacuum furnace for vacuum quenching treatment, the quenching temperature is T2, the holding time is t2, and then sent into nitrogen at -90°C for rapid cooling to room temperature. The hardness range of the finished parts after vacuum quenching treatment is HRC42-45°;

[0013] S6: Tempering and polishing: first insert the inner plug of the clamp claw from the auxiliary ring section into the cylindrical section, then cut off the auxiliary ring section, and then send the cut finished part and the inner plug of the clamp claw into the tempering furnace for tempering treatment. The tempering temperature is T3, the insulation time is t3, and then it is cooled to room temperature. The hardness range of the finished part after tempering treatment is HRC38-40°; take out the finished part after tempering treatment, and take out the inner plug of the clamp claw from the cylindrical section, and then polish the finished part to obtain the finished grid-shaped mold part of the double-layer structure pipe.

[0014] The beneficial effects of the processing method of the grid-shaped die part of the double-layer structure pipe provided by the present invention are as follows: The hollow structure core mold is a single independent grid-shaped die part, and the wall thickness of the grid part is relatively thin. During the finish machining, heat treatment, and surface treatment processes, the grid structure is prone to inward deformation due to the loss of support, resulting in a reduction in the size of the grid part of the processed hollow structure core mold, and ultimately leading to the scrapping of the processed hollow structure core mold because it does not meet the dimensional requirements. The processing method of the grid-shaped die part of the double-layer structure pipe provided by the present invention cuts out a blank including an auxiliary ring section, a cylindrical section, and a clamping section connected in sequence. Before the tempering treatment, the auxiliary ring section can provide effective support for multiple grids in the cylindrical section. During the tempering treatment, a hoop claw inner plug is inserted into the cylindrical section to provide support for the workpiece during the tempering process and prevent it from undergoing inward deformation during the tempering process, thereby ensuring that the quality of the finally processed workpiece meets the requirements.

[0015] During the processing, first, pre-hardening treatment is performed on the rough-machined workpiece, and then the finish-machined workpiece is sequentially subjected to quenching treatment and tempering treatment. The pre-hardening treatment can make the rough-machined workpiece reach a certain hardness before quenching, so as to reduce the drastic change of the internal structure of the workpiece during the quenching process, thereby reducing the stress and deformation generated during the quenching process; through the quenching treatment of the finish-machined workpiece, the finish-machined workpiece can obtain high hardness and high wear resistance; through the tempering treatment of the quenched finish-machined workpiece, the quenched martensite generated during the quenching process can decompose to form tissues such as tempered martensite with higher toughness and plasticity, thereby improving the impact resistance and deformation resistance of the workpiece, further increasing the hardness and strength of the workpiece, and reducing the possibility of cracking of the processed workpiece during use.

[0016] Through the above steps, the present invention effectively solves the technical problem in the prior art that the grid part of the hollow structure core mold is prone to inward deformation due to the loss of support during the processing, resulting in the scrapping of the processed hollow structure core mold because it does not meet the dimensional requirements.

[0017] Further, the heating temperature T1 is 870 °C, and the holding time t1 is 3 hours.

[0018] Further, the quenching temperature T2 is 1030 °C, and the holding time t2 is 1 hour.

[0019] Further, the tempering temperature T3 is 515 °C, and the holding time t3 is 2 hours.

[0020] Further, the path width b1 is less than or equal to 0.3 mm.

[0021] Beneficial effects: The path width of wire cutting is less than or equal to 0.3 mm, and the cut is small. It can not only separate two adjacent grids but also has no impact on subsequent heat treatment processing.

[0022] Further, in the step S1, a machining allowance with a width of b2 is reserved on one side of the raw material to obtain the blank.

[0023] Beneficial effects: During the manufacturing process of raw materials, there may be problems such as dimensional errors and surface unevenness. When cutting the raw material into a blank, by reserving a machining allowance, these errors can be gradually corrected during subsequent processing to ensure the dimensional accuracy and shape accuracy of the final part; in the rough machining stage, a larger machining allowance helps to remove defects on the surface of the blank and lay a good foundation for finish machining; in the finish machining stage, through the reserved machining allowance, the surface of the part can be finely processed to remove tool marks and minute unevenness left by rough machining, thereby obtaining a smooth surface.

[0024] Further, the machining allowance b2 is 1 mm.

[0025] Further, the wire cutting path of the tool is T-shaped.

[0026] Further, in the step S1, one end of the auxiliary ring section facing the cylindrical section has a connection section for connecting with the cylindrical section, and the radial dimension of the connection section is the same as that of the cylindrical section.

[0027] Further, in the step S3, after the rough-machined workpiece is insulated, it is cooled to room temperature in the air. In the step S6, after the finish-machined workpiece is tempered, it is cooled to room temperature in the air.

[0028] Beneficial effects: The hardness of the workpiece after pre-hardening treatment is relatively high. If a rapid cooling method such as water cooling is used, the rough-machined workpiece may cause stress, deformation, and even cracking due to the temperature difference between the inside and outside. However, when cooled in the air, the cooling rate is relatively slow, and the rough-machined workpiece can dissipate heat more evenly, thereby reducing the risk of stress and deformation; although the hardness of the finish-machined workpiece after tempering treatment decreases, its internal stress is still relatively large. If a rapid cooling method such as water cooling is used, the finish-machined workpiece may crack due to the release of stress. However, when cooled in the air, the cooling rate is slow, and the finish-machined workpiece can release stress more smoothly, thereby avoiding the risk of cracking of the finish-machined workpiece. Description of the Drawings

[0029] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0030] Figure 1 A flow chart of a method for processing a grid-shaped mold part of a double-layer structure pipe provided by the present invention;

[0031] Figure 2 It is a schematic structural diagram of a rough-machined part in the method for machining a grid-shaped mold part of a double-layer structure pipe provided by the present invention;

[0032] Figure 3 for Figure 2 Cross-section of a rough machined part;

[0033] Figure 4 It is a schematic diagram of the wire cutting path of the tool during rough machining;

[0034] Figure 5 Side view of the finished part before removing the auxiliary ring segment and the connecting segment;

[0035] Figure 6 Side view of the finished part after removing the auxiliary ring segment and connecting segment.

[0036] Description of reference numerals:

[0037] 1. Auxiliary ring section; 2. Cylinder section; 3. Clamping section; 4. Clamping claw plug; 5. Wire cutting path; 6. Connecting section; 7. Groove. DETAILED DESCRIPTION

[0038] The principle and spirit of the present invention are explained in detail below with reference to several representative embodiments of the present invention.

[0039] Embodiment of the processing method of the grid-shaped mold part of the double-layer structure pipe provided by the present invention:

[0040] like Figure 1 As shown, the processing method of the grid-shaped mold part of the double-layer structure pipe includes the following steps:

[0041] S1: blank cutting: cutting the raw material according to the design drawing to obtain a blank including an auxiliary ring segment, a cylindrical segment and a clamping segment connected in sequence, wherein the radial dimensions of the auxiliary ring segment and the clamping segment are both larger than the radial dimension of the cylindrical segment;

[0042] S2: Wire-cut rough machining: Use tools evenly distributed circumferentially with multiple ring blanks to perform wire-cut machining on the auxiliary ring section and the cylindrical section. The width of the wire-cut path is b1. When the tool performs wire-cut machining, it penetrates the thickness of the cylindrical section but does not penetrate the thickness of the auxiliary ring section, dividing the cylindrical section into multiple spaced-apart grids. After the wire-cut rough machining, a rough machined part is obtained;

[0043] S3: Pre-hardening treatment: First, send the rough machined part into a high-temperature furnace for heating. The heating temperature is T1, and the holding time is t1. Then, cool it to room temperature. After the pre-hardening treatment, the hardness range of the rough machined part is HRC28 - 32°;

[0044] S4: Lathe finish machining: First, clamp the auxiliary ring section of the rough machined part after pre-hardening treatment on the lathe, and finish machine the outer peripheral surface, inner peripheral surface, end surface, and outer extended part of the clamped section to the design dimensions; then loosen the auxiliary ring section, clamp the clamped section on the lathe, and finish machine the outer peripheral surface and inner peripheral surface of the grids of the cylindrical section to the design dimensions to obtain a finish machined part;

[0045] S5: Vacuum quenching treatment: Send the finish machined part into a vacuum furnace for vacuum quenching treatment. The quenching temperature is T2, and the holding time is t2. Then, send it into nitrogen at -90°C for rapid cooling to room temperature. After the vacuum quenching treatment, the hardness range of the finish machined part is HRC42 - 45°;

[0046] S6: Tempering and polishing treatment: First, insert the ferrule inner plug into the cylindrical section from the auxiliary ring section, then cut off the auxiliary ring section, and then send the cut finish machined part and the ferrule inner plug into a tempering furnace for tempering treatment. The tempering temperature is T3, and the holding time is t3. Then, cool it to room temperature. After the tempering treatment, the hardness range of the finish machined part is HRC38 - 40°; Take out the finish machined part after the tempering treatment, and take out the ferrule inner plug from the cylindrical section. Then, perform polishing treatment on the finish machined part to obtain the finished product of the grid-shaped die part of the double-layer structure pipe.

[0047] Among them, the path width b1 is less than or equal to 0.3 mm, and a machining allowance with a width of b2 is left on one side of the raw material to obtain a blank. In this embodiment, b2 is 1 mm. In other embodiments, b2 can be determined according to the machining conditions.

[0048] In this embodiment, the heating temperature T1 is 870°C, the holding time t1 is 3 hours; the quenching temperature T2 is 1030°C, the holding time t2 is 1 hour; the tempering temperature T3 is 515°C, and the holding time t3 is 2 hours.

[0049] During the quenching process, large internal stresses will be generated in the workpiece. If these internal stresses cannot be eliminated in time, it is easy to cause the workpiece to crack; through pre-hardening treatment, the initial hardness of the workpiece can be improved, and its cutting performance or cold extrusion forming performance can be improved. The heating temperature of the pre-hardening treatment is lower than that of the quenching treatment, which can avoid excessive stress and deformation of the workpiece during subsequent quenching, reduce the quenching stress to a certain extent, and reduce the cracking risk; by tempering the workpiece after quenching treatment, the quenching stress can be further eliminated, the toughness of the workpiece can be improved, and the hardness and strength of the workpiece can be adjusted. The tempering temperature is lower than the heating temperature and the quenching temperature, which can ensure that the workpiece obtains ideal mechanical properties, further optimize the toughness and plasticity of the workpiece, and make the workpiece more resistant to impact and deformation during use.

[0050] In this embodiment, as Figure 4 shown, the wire cutting path 5 of the tool is T-shaped. In other embodiments, the wire cutting path 5 of the tool only needs to ensure that the tool penetrates the thickness of the cylindrical section 2 and does not penetrate the thickness of the auxiliary ring section 1.

[0051] In this embodiment, as Figure 2 and Figure 3 shown, one end of the auxiliary ring section 1 facing the cylindrical section 2 has a connecting section 6 for connecting with the cylindrical section 2, and the radial dimension of the connecting section 6 is the same as that of the cylindrical section 2.

[0052] In this embodiment, as Figure 2 and Figure 3 shown, the clamping section 3 has a groove 7.

[0053] In this embodiment, the rough-machined workpiece is kept warm and then cooled to room temperature in the air in step S3, and the finish-machined workpiece is tempered and then cooled to room temperature in the air in step S6.

[0054] Before the finish-machined workpiece removes the auxiliary ring section and the connecting section, as Figure 5 shown, after the finish-machined workpiece removes the auxiliary ring section and the connecting section, as Figure 6 shown.

[0055] It should be noted that in this embodiment, the outer shape of the hoop claw inner plug 4 matches the outer shapes of the auxiliary ring section 1 and the cylindrical section 2 after finish machining. In other embodiments, the outer shape of the hoop claw inner plug 4 only matches the outer shape of the cylindrical section 2.

[0056] Based on the above description of this specification, those skilled in the art can also understand the following terms used, such as "upper", "lower", "front", "rear", "left", "right", "width", "horizontal", "top", "bottom", "inner", "outer", etc. The terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings of this specification. They are only for the purpose of facilitating the description of the solution of the present invention and simplifying the description, rather than explicitly or implicitly indicating that the devices or elements involved must have the specific orientation, be constructed and operate in the specific orientation. Therefore, the above terms of orientation or positional relationship cannot be understood or interpreted as a limitation to the solution of the present invention.

[0057] In addition, in the description of this specification, the meaning of "a plurality of" is at least two, such as two, three or more, etc., unless otherwise specifically defined.

Claims

1. A method for processing a grid-shaped mold part of a double-layer structure pipe, characterized in that: The steps include: S1: blank cutting: cutting the raw material according to the design drawing to obtain a blank including an auxiliary ring segment, a cylindrical segment and a clamping segment connected in sequence, wherein the radial dimensions of the auxiliary ring segment and the clamping segment are both larger than the radial dimension of the cylindrical segment; S2: Wire cutting rough machining: Use multiple cutters evenly spaced circumferentially on the ring blank to perform wire cutting on the auxiliary ring segment and the cylinder segment. The wire cutting path width is b1. During wire cutting, the cutter penetrates the thickness of the cylinder segment but does not penetrate the thickness of the auxiliary ring segment, dividing the cylinder segment into multiple grids arranged at intervals. After the wire cutting rough machining is completed, a rough machined part is obtained; S3: Pre-hardening treatment: First, the rough-machined workpiece is sent into a high-temperature furnace for heating at a temperature of T1 and a holding time of t1, and then cooled to room temperature. After pre-hardening treatment, the hardness range of the rough-machined workpiece is HRC28-32°; S4: Lathe finishing: First, the auxiliary ring segment of the rough-machined part after pre-hardening treatment is clamped on the lathe, and the outer peripheral surface, inner peripheral surface, end surface and outer extension part of the clamping segment are finished to the designed size; then, the auxiliary ring segment is loosened, the clamping segment is clamped on the lathe, and the outer peripheral surface and inner peripheral surface of the cylindrical segment grille are finished to the designed size to obtain a finished part; S5: Vacuum quenching treatment: The finished parts are sent into a vacuum furnace for vacuum quenching treatment, the quenching temperature is T2, the holding time is t2, and then sent into nitrogen at -90°C for rapid cooling to room temperature. The hardness range of the finished parts after vacuum quenching treatment is HRC42-45°; S6: Tempering and polishing: first insert the inner plug of the clamp claw from the auxiliary ring section into the cylindrical section, then cut off the auxiliary ring section, and then send the cut finished part and the inner plug of the clamp claw into the tempering furnace for tempering treatment. The tempering temperature is T3, the insulation time is t3, and then it is cooled to room temperature. The hardness range of the finished part after tempering treatment is HRC38-40°; take out the finished part after tempering treatment, and take out the inner plug of the clamp claw from the cylindrical section, and then polish the finished part to obtain the finished grid-shaped mold part of the double-layer structure pipe.

2. The method for processing the grid-shaped mold parts of the double-layer structure pipe according to claim 1, characterized in that: The heating temperature T1 is 870° C., and the heat preservation time t1 is 3 hours.

3. The method for processing the grid-shaped mold parts of the double-layer structure pipe according to claim 2 is characterized in that: The quenching temperature T2 is 1030° C., and the holding time t2 is 1 hour.

4. The method for processing the grid-shaped mold parts of the double-layer structure pipe according to claim 3 is characterized in that: The tempering temperature T3 is 515° C., and the holding time t3 is 2 hours.

5. The method for processing a grid-shaped mold part of a double-layer structure pipe according to any one of claims 1 to 3, characterized in that: The path width b1 is less than or equal to 0.3 mm.

6. The method for processing a grid-shaped mold part of a double-layer structure pipe according to any one of claims 1 to 3, characterized in that: In the step S1, a machining allowance with a width of b2 is left on one side of the raw material to obtain the blank.

7. The method for processing the grid-shaped mold parts of the double-layer structure pipe according to claim 6, characterized in that: The machining allowance b2 is 1 mm.

8. The method for processing a grid-shaped mold part of a double-layer structure pipe according to any one of claims 1 to 3, characterized in that: The wire cutting path of the tool is T-shaped.

9. The method for processing a grid-shaped mold part of a double-layer structure pipe according to any one of claims 1 to 3, characterized in that: In the step S1, one end of the auxiliary ring segment facing the cylindrical segment has a connecting segment for connecting with the cylindrical segment, and the radial dimension of the connecting segment is the same as the radial dimension of the cylindrical segment.

10. The method for processing a grid-shaped mold part of a double-layer structure pipe according to any one of claims 1 to 3, characterized in that: In the step S3, the rough-machined workpiece is kept warm and then cooled to room temperature in the air. In the step S6, the fine-machined workpiece is tempered and then cooled to room temperature in the air.

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