Machining process for inner hole of speed reducer box body

Abstract

The invention discloses a speed reducer box body inner hole machining process, and belongs to the field of speed reducer box body machining, a large drill bit is firstly used for preliminary drilling, most materials are rapidly removed, the initial drilling speed and efficiency can be improved, when drilling holes in the two ends are about to approach each other, using of the large drill bit is stopped, and a small drill bit is replaced, so that the drilling efficiency is improved. By means of the small drill bit, more adjusting space and materials can be reserved for the following steps for final forming, in the process that the small drill bit is used for fine drilling, the flow of cooling liquid can be increased around a drilled hole, the cooling effect is improved through a gap reserved by the small drill bit, heat accumulation and material stress are reduced, and the service life of the drill bit is prolonged. Due to the fact that the small drill bit is used, the material bearing capacity is small in the breaking-through process, impact and possible deviation in the breaking-through process can be reduced, meanwhile, after the large drill bit is finally used for remachining, any tiny deviation generated by machining of the small drill bit can be effectively corrected, and the precision of the hole diameter and the surface smoothness are guaranteed.

Description

Technical Field

[0001] The invention relates to the field of speed reducer housing processing, and more specifically to a speed reducer housing inner hole processing technology. Background Art

[0002] The reducer housing is the basic component for installing each transmission shaft. Since each shaft will generate a relatively large reaction force when transmitting torque when the reducer is working, and it will act on the housing, the housing is required to have sufficient rigidity to ensure the relative position accuracy of each transmission shaft. The use of a metal structure housing can obtain greater strength and rigidity, and has a compact structure and light weight.

[0003] Traditional methods for processing holes in reducer housings mostly use ordinary drilling or milling processes. The drill bit of ordinary drilling processes is prone to deviation due to insufficient long-distance guidance, especially in deep hole processing. The deeper the drilling depth, the greater the risk of drill bit deviation, which may lead to poor centering of the final hole. Long-distance drilling may cause more heat accumulation and stress concentration, which may affect the surface integrity and accuracy of the final hole. Poor chip removal during drilling can easily lead to overheating and wear of the drill bit, affecting processing efficiency and quality.

[0004] Therefore, a new process method is urgently needed to improve the processing quality and efficiency of the inner holes of the reducer housing. Summary of the invention

[0005] 1. Technical issues to be solved In view of the problems existing in the prior art, the purpose of the present invention is to provide a process for processing the inner holes of a reducer case. By first using a large drill bit for preliminary drilling, most of the material can be quickly removed. This step can improve the initial drilling speed and efficiency. When the holes at both ends are about to approach each other, the use of the large drill bit is suspended and replaced with a small drill bit. The use of the small drill bit can leave more adjustment space and material for the final forming in the next steps. In the process of fine drilling with a small drill bit, the flow of coolant can be increased around the drill hole, and the gap left by the smaller drill bit can be used to improve the cooling effect, reduce heat accumulation and material stress. Since a small drill bit is used, the material bearing capacity during the drilling process is smaller, which can reduce the impact and possible deviation during the drilling. At the same time, after the final reprocessing with a large drill bit, any slight deviation caused by the small drill bit processing can be effectively corrected to ensure the accuracy of the hole diameter and the surface finish.

[0006] 2. Technical solution

[0007] To solve the above problems, the present invention adopts the following technical solutions.

[0008] A process for machining inner holes of a reducer housing comprises the following steps: S1. Use materials with high rigidity and good processing performance to make the reducer housing; S2. According to the parameters of the inner hole to be formed, a CNC milling machine is selected to perform rough machining on the inner hole to remove most of the excess. During the rough machining, a method of synchronous drilling is adopted on both sides of the inner hole; S3. During the drilling process, the centering accuracy of the holes on both sides is ensured in real time until the holes are drilled through; S4. After opening, use a high-precision CNC internal grinding machine to fine-process the inner hole to achieve the required accuracy and surface finish; S5, clean the inner hole, remove all chips and contamination generated during the processing, and then conduct the final quality inspection; The method of drilling holes on both sides of the inner hole and then breaking through can significantly improve the centering accuracy of the hole. Drilling holes from both ends can effectively reduce the deviation and bending problems that may occur in deep hole drilling. When breaking through, fine adjustments can be made to ensure the centering of the hole and reduce errors. In addition, drilling holes from both sides can more effectively control the heat accumulation and internal stress of the material during the processing process, which helps to improve the surface quality and structural integrity of the hole after processing. Drilling holes in sections can better remove chips and reduce blockage and wear during drilling, thereby improving the service life of the drill bit and processing efficiency.

[0009] As a further improvement of the present invention, the material is one of cast iron or aluminum alloy.

[0010] As a further improvement of the present invention, the inner hole size tolerance deviation does not exceed 0.03 mm, and the surface roughness Ra does not exceed 1.2 microns.

[0011] As a further improvement of the present invention, in step S3, when the holes on both sides are close to being drilled through, the process is paused, a drill bit with a smaller diameter is replaced for drilling through, and coolant is injected into the inner hole. After drilling through, the drill bit of the original size is replaced for final processing of the inner hole to ensure the consistency of the hole diameter and the smooth surface. A large drill bit is used for preliminary drilling to quickly remove most of the material. This step can improve the initial drilling speed and efficiency. When the holes at both ends are about to approach each other, the use of the large drill bit is paused and replaced with a small drill bit. The use of the small drill bit can leave more adjustment space and materials for the final forming for the next steps. In the process of fine drilling with a small drill bit, the flow of coolant can be increased around the drill hole, and the gap left by the smaller drill bit can be used to improve the cooling effect and reduce heat accumulation and material stress. Since a small drill bit is used, the material bearing capacity during the drilling process is smaller, and the impact and possible deviation during the drilling process can be reduced.

[0012] As a further improvement of the present invention, the drill bit with a smaller diameter is replaced when the drilling distance of the holes on both sides is 10-20% of the inner hole depth.

[0013] As a further improvement of the present invention, the feed rate of the small-diameter drill bit is 30%-50% of the feed rate of the original-size drill bit, which can reduce the pressure and heat generated by rapid drilling and better ensure the accuracy of inner hole forming.

[0014] As a further improvement of the present invention, a small-diameter drill bit is used to drill forward and backward to help remove chips and reduce the pressure on the borehole wall. It can also reduce drill bit deviation or hole wall damage caused by sudden release of pressure from the drilled material during drilling.

[0015] As a further improvement of the present invention, the diameter of the small-diameter drill bit should be at least 5 mm smaller than the diameter of the original-size drill bit, so as to leave sufficient gaps for the circulation of coolant when the holes at both ends are almost through, and to ensure the accuracy of the final hole diameter. Sufficient gaps can promote the effective flow of coolant, help control the temperature during the processing, reduce thermal stress and improve the processing quality, and avoid excessive impact or material deformation when the holes are finally through. At the same time, after the final reprocessing with a large drill bit, any slight deviations caused by processing with a small drill bit can be effectively corrected to ensure the accuracy of the hole diameter and surface finish.

[0016] As a further improvement of the present invention, after step S4, the inner hole surface is super-finished using laser polishing technology to further improve the surface finish, and the laser polishing technology is a pulse or continuous wave laser.

[0017] As a further improvement of the present invention, the quality inspection includes size inspection and surface inspection, the size inspection includes the diameter, depth and position accuracy of the inner hole, and the surface inspection includes cracks, scratches and concave-convex areas.

[0018] 3. Beneficial effects

[0019] The present invention uses a large drill bit to perform preliminary drilling first to quickly remove most of the material. This step can improve the initial drilling speed and efficiency. When the holes at both ends are about to approach each other, the use of the large drill bit is stopped and replaced with a small drill bit. The use of the small drill bit can leave more adjustment space and material for the next step for final forming. In the process of fine drilling with a small drill bit, the flow of coolant can be increased around the drill hole, and the gap left by the smaller drill bit can be used to improve the cooling effect, reduce heat accumulation and material stress. Since a small drill bit is used, the material bearing capacity during the breakthrough process is smaller, which can reduce the impact and possible offset during the breakthrough. At the same time, after the final reprocessing with a large drill bit, any slight deviation caused by the small drill bit processing can be effectively corrected to ensure the accuracy of the hole diameter and the surface finish. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1is a process flow chart of the present invention; Figure 2 This is a table of inner hole quality detection data for Examples 1-4 of the present invention and a comparative example. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0022] Embodiment 1:

[0023] A process for machining inner holes of a reducer housing comprises the following steps: S1. Use cast iron material to make the reducer housing; S2, the inner hole diameter is 30mm, the depth is 50mm, and a CNC milling machine is selected to perform rough machining on the inner hole to remove most of the excess. During rough machining, the inner hole is drilled synchronously on both sides, and the diameter of the original size drill bit is 28mm; S3. During the drilling process, ensure the centering accuracy of the holes on both sides in real time until the holes are drilled through. When the holes on both sides are close to being drilled through, pause and replace with a 22mm drill bit to drill through. Inject coolant into the inner hole. After drilling through, replace the original-size drill bit to perform final processing on the inner hole to ensure the consistency of the hole diameter and smooth surface. Replace the 22mm drill bit when the drilling distance of the holes on both sides is 20% of the inner hole depth. The feed rate of the small drill bit is 50% of the feed rate of the original-size drill bit. Use a small-amplitude drilling and retraction method. S4. After opening, the inner hole is finely processed by a high-precision CNC internal grinding machine to achieve the required accuracy and surface finish, and the inner hole surface is super-finished using continuous wave laser polishing technology to further improve the surface finish; S5. Clean the inner hole, remove all chips and contamination generated during the processing, and then conduct the final quality inspection. The quality inspection includes dimensional inspection and surface inspection. The dimensional inspection includes the diameter, depth and position accuracy of the inner hole, and the surface inspection includes cracks, scratches and bumps.

[0024] Embodiment 2:

[0025] A process for machining inner holes of a reducer housing comprises the following steps: S1. Use cast iron material to make the reducer housing; S2, the inner hole diameter is 30mm, the depth is 50mm, and a CNC milling machine is selected to perform rough machining on the inner hole to remove most of the excess. During rough machining, the inner hole is drilled synchronously on both sides, and the diameter of the original size drill bit is 28mm; S3. During the drilling process, ensure the centering accuracy of the holes on both sides in real time until the holes are drilled through. When the holes on both sides are almost drilled through, pause and replace with a 20mm drill bit to drill through. Inject coolant into the inner hole. After drilling through, replace the original-size drill bit to perform final processing on the inner hole to ensure the consistency of the hole diameter and smooth surface. Replace the 20mm drill bit when the drilling distance of the holes on both sides is 15% of the inner hole depth. The feed rate of the small drill bit is 40% of the feed rate of the original-size drill bit. Use a small-amplitude drilling and retraction method. S4. After opening, the inner hole is finely processed by a high-precision CNC internal grinding machine to achieve the required accuracy and surface finish, and the inner hole surface is super-finished using continuous wave laser polishing technology to further improve the surface finish; S5. Clean the inner hole, remove all chips and contamination generated during the processing, and then conduct the final quality inspection. The quality inspection includes dimensional inspection and surface inspection. The dimensional inspection includes the diameter, depth and position accuracy of the inner hole, and the surface inspection includes cracks, scratches and bumps.

[0026] Embodiment 3:

[0027] A process for machining inner holes of a reducer housing comprises the following steps: S1. Use cast iron material to make the reducer housing; S2, the inner hole diameter is 30mm, the depth is 50mm, and a CNC milling machine is selected to perform rough machining on the inner hole to remove most of the excess. During rough machining, the inner hole is drilled synchronously on both sides, and the diameter of the original size drill bit is 28mm; S3. During the drilling process, ensure the centering accuracy of the holes on both sides in real time until the holes are drilled through. When the holes on both sides are almost drilled through, pause and replace with an 18mm drill bit to drill through. Inject coolant into the inner hole. After drilling through, replace the original-size drill bit to perform final processing on the inner hole to ensure the consistency of the hole diameter and smooth surface. Replace the 18mm drill bit when the drilling distance of the holes on both sides is 10% of the inner hole depth. The feed rate of the small drill bit is 30% of the feed rate of the original-size drill bit. Use a small-amplitude drilling and retraction method. S4. After opening, the inner hole is finely processed by a high-precision CNC internal grinding machine to achieve the required accuracy and surface finish, and the inner hole surface is super-finished using continuous wave laser polishing technology to further improve the surface finish; S5. Clean the inner hole, remove all chips and contamination generated during the processing, and then conduct the final quality inspection. The quality inspection includes dimensional inspection and surface inspection. The dimensional inspection includes the diameter, depth and position accuracy of the inner hole, and the surface inspection includes cracks, scratches and bumps.

[0028] Embodiment 4:

[0029] A process for machining inner holes of a reducer housing comprises the following steps: S1. Use cast iron material to make the reducer housing; S2, the inner hole diameter is 30mm, the depth is 50mm, and a CNC milling machine is selected to perform rough machining on the inner hole to remove most of the excess. During rough machining, the inner hole is drilled synchronously on both sides, and the diameter of the original size drill bit is 28mm; S3. During the drilling process, the centering accuracy of the holes on both sides is ensured in real time until the holes are drilled through. When the drilling distance of the holes on both sides is 10% of the inner hole depth, the feed rate is adjusted to 30% of the original feed rate, and a small amplitude drilling and retraction method is adopted; S4. After opening, the inner hole is finely processed by a high-precision CNC internal grinding machine to achieve the required accuracy and surface finish, and the inner hole surface is super-finished using continuous wave laser polishing technology to further improve the surface finish; S5. Clean the inner hole, remove all chips and contamination generated during the processing, and then conduct the final quality inspection. The quality inspection includes dimensional inspection and surface inspection. The dimensional inspection includes the diameter, depth and position accuracy of the inner hole, and the surface inspection includes cracks, scratches and bumps.

[0030] Comparison example: A process for machining inner holes of a reducer housing comprises the following steps: S1. Use cast iron material to make the reducer housing; S2, the inner hole diameter is 30mm, the depth is 50mm, and the CNC milling machine is selected to rough-process the inner hole to remove most of the excess. The diameter of the original size drill bit is 28mm; S3. Use a high-precision CNC internal grinding machine to fine-machine the inner hole to achieve the required accuracy and surface finish, and use continuous wave laser polishing technology to super-finish the inner hole surface to further improve the surface finish; S4. Clean the inner hole, remove all chips and contamination generated during the processing, and then conduct the final quality inspection. The quality inspection includes dimensional inspection and surface inspection. The dimensional inspection includes the diameter, depth and position accuracy of the inner hole, and the surface inspection includes cracks, scratches and bumps.

[0031] See also Figure 2, Examples 1, 2, and 3 show that the use of a small-diameter drill and coolant can significantly improve the accuracy (tolerance ±0.01mm), compared to Example 4 (tolerance ±0.03mm) and the control example (tolerance ±0.05mm) without using a small drill. This shows that the use of a small drill helps to control the accuracy and stability during the processing. The examples using a small-diameter drill (Examples 1, 2, and 3) obtained a lower surface roughness (0.5-0.8 microns), while the surface roughness of Example 4 without a small-diameter drill was higher (1.1 microns), almost close to the surface roughness of the control example (1.4 microns). This proves that a small-diameter drill is beneficial to improving the surface quality during the drilling and retraction process, and in the implementation process, it was found that in the surface quality inspection of the inner holes formed by Examples 1, 2, and 3, cracks, scratches, and deformation rarely occurred, and the frequency of the above situations in ordinary processing is relatively high. It can be seen that the method of drilling holes on both sides and then modifying a small-diameter drill to open them can improve the stability of the inner hole forming.

[0032] It is worth noting that the process parameters of finishing and super finishing of Examples 1-4 and the comparative example are completely consistent, so as to reduce the influence of the drilling process on the inner hole forming result.

[0033] The above are only preferred specific implementations of the present invention; however, the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and improved concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A process for machining inner holes of a reducer housing, characterized in that: The following steps are involved: S1. Use materials with high rigidity and good processing performance to make the reducer housing; S2. According to the parameters of the inner hole to be formed, a CNC milling machine is selected to perform rough machining on the inner hole to remove most of the excess. During the rough machining, a method of synchronous drilling is adopted on both sides of the inner hole; S3. During the drilling process, the centering accuracy of the holes on both sides is ensured in real time until the holes are drilled through. When the holes on both sides are almost drilled through, the drilling is paused, and a drill bit with a smaller diameter is replaced to drill through. Coolant is injected into the inner hole. After drilling through, the drill bit of the original size is replaced to perform final processing on the inner hole to ensure the consistency of the hole diameter and smooth surface. S4. After opening, use a high-precision CNC internal grinding machine to fine-process the inner hole to achieve the required accuracy and surface finish; S5. Clean the inner hole to remove all chips and contamination generated during the processing, and then conduct the final quality inspection.

2. A process for machining inner holes of a reducer housing according to claim 1, characterized in that: The material is one of cast iron or aluminum alloy.

3. A process for machining inner holes of a reducer housing according to claim 1 or 2, characterized in that: The inner hole size deviation does not exceed 0.03 mm, and the surface roughness Ra does not exceed 1.2 microns.

4. The process for machining inner holes of a reducer housing according to claim 1, characterized in that: When the drilling distance of the holes on both sides is 10-20% of the inner hole depth, replace the drill bit with a smaller diameter.

5. A process for machining inner holes of a reducer housing according to claim 1 or 4, characterized in that: The feed rate of the small diameter drill bit is 30%-50% of the feed rate of the full size drill bit.

6. The process for machining inner holes of a reducer housing according to claim 1, characterized in that: When replacing a small diameter drill bit to break through, use a small drilling and retreat method.

7. The process for machining inner holes of a reducer housing according to claim 1, characterized in that: The diameter of the small-diameter drill bit should be at least 5 mm smaller than the diameter of the original-size drill bit, so as to leave enough gaps for the circulation of coolant when the holes at both ends are almost through, and to ensure the accuracy of the final hole diameter.

8. The process for machining inner holes of a reducer housing according to claim 1, characterized in that: After step S4, the inner hole surface is super-finished using laser polishing technology to further improve the surface finish. The laser polishing technology is a pulse or continuous wave laser.

9. The process for machining inner holes of a reducer housing according to claim 1, characterized in that: The quality inspection includes size inspection and surface inspection. The size inspection includes the diameter, depth and position accuracy of the inner hole, and the surface inspection includes cracks, scratches and concave-convex areas.

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