A processing technology for the inner hole of a speed reduction machine case

Abstract

The present invention discloses a processing technology for the inner hole of a speed reducer housing, belonging to the field of speed reducer housing processing. First, a large drill bit is used for preliminary drilling to quickly remove most of the material, which can improve the initial drilling speed and efficiency. When the drill 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 material for the next steps for final forming. During the process of using the small drill bit for fine drilling, the flow rate of the coolant can be increased around the drill hole, and the gap left by the smaller drill bit is utilized to improve the cooling effect, reduce heat accumulation and material stress. Since a small drill bit is used, the material bearing capacity during the punching process is smaller, which can reduce the impact and possible deviation during punching. At the same time, after finally reprocessing with the large drill bit, any tiny deviation generated by the small drill bit processing can be effectively corrected to ensure the accuracy of the hole diameter and the surface finish.

Description

Technical Field

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

[0002] The reducer housing is a basic component for installing each transmission shaft; since a relatively large reaction force is generated when each shaft transmits torque during the operation of the reducer and acts on the housing, it is required that the housing has sufficient stiffness to ensure the relative position accuracy of each transmission shaft. Using a metal structure housing can obtain greater strength and stiffness, and has a compact structure and a relatively light weight.

[0003] In traditional processing methods for the inner hole of a reducer housing, ordinary drilling or milling processes are mostly used. In the ordinary drilling process, the drill bit 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 result in more heat accumulation and stress concentration, which may affect the surface integrity and accuracy of the final hole. During the drilling process, chip removal is not smooth, which is likely to cause the drill bit to overheat and wear, affecting the processing efficiency and quality.

[0004] Therefore, there is an urgent need for a new process method to improve the processing quality and efficiency of the inner hole of a reducer housing. Summary of the Invention

[0005] 1. Technical Problems to be Solved

[0006] Aiming at the problems existing in the prior art, the purpose of the present invention is to provide a processing technology for the inner hole of a reducer housing. First, a large drill bit is used for preliminary drilling to quickly remove most of the material, which can improve the initial drilling speed and efficiency. When the drillings at both ends are about to approach each other, the use of the large drill bit is paused, and a small drill bit is replaced. The use of the small drill bit can leave more adjustment space and material for the next steps for final forming. During the process of using the small drill bit for fine drilling, the flow rate of the coolant can be increased around the drilling, and the gap left by the smaller drill bit can be used to improve the cooling effect, reduce heat accumulation and material stress. Since the small drill bit is used, the material bearing force during the punching process is smaller, which can reduce the impact and possible deviation during punching. At the same time, after finally reprocessing with the large drill bit, any small deviations generated by the small drill bit processing can be effectively corrected to ensure the accuracy of the hole diameter and the surface finish.

[0007] 2. Technical Solutions

[0008] To solve the above problems, the present invention adopts the following technical solutions.

[0009] A processing technology for the inner hole of a reducer housing includes the following steps:

[0010] S1. Select a material with high rigidity and good machining performance to make the reducer housing;

[0011] S2. Select a CNC milling machine according to the inner hole parameters to be formed and rough machine the inner hole to remove most of the surplus. When rough machining, adopt the method of synchronous drilling on both sides of the inner hole;

[0012] S3. Ensure the centering accuracy of the drilling on both sides in real time during the drilling process until the drilling is completed and the hole is penetrated;

[0013] S4. After penetration, use a high-precision CNC internal cylindrical grinder to finish machine the inner hole to achieve the required accuracy and surface finish;

[0014] S5. Clean the inner hole to remove all chips and contaminants generated during the machining process, and then conduct a final quality inspection;

[0015] Adopting the method of drilling on both sides of the inner hole and then penetrating can significantly improve the centering accuracy of the hole. Drilling from both ends can effectively reduce the offset and bending problems that may occur to the drill bit during deep hole drilling. When penetrating, the centering of the hole can be ensured through fine adjustment to reduce errors. In addition, drilling from both sides can more effectively control the heat accumulation and internal stress of the material during the machining process, which helps to improve the surface quality and structural integrity of the machined hole. Segmenting the drilling can better discharge chips, reduce blockage and wear during drilling, thereby increasing the service life and machining efficiency of the drill bit.

[0016] As a further improvement of the present invention, the material is one of cast iron or aluminum alloy.

[0017] As a further improvement of the present invention, the dimensional tolerance deviation of the inner hole does not exceed 0.03 mm, and the surface roughness Ra does not exceed 1.2 microns.

[0018] As a further improvement of the present invention, in step S3, when the drilling on both sides is close to penetration, pause, replace the drill bit with a smaller diameter to penetrate, and inject coolant into the inner hole. After penetration, replace the drill bit with the original size to conduct the final machining of the inner hole to ensure the diameter consistency and surface smoothness. Use a large drill bit for preliminary drilling to quickly remove most of the material. This step can improve the initial drilling speed and efficiency. When the drilling at both ends is about to approach each other, pause using the large drill bit and replace it 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. During the process of fine drilling with the small drill bit, the coolant flow rate can be increased around the drilling, and the cooling effect can be improved by using the gap left by the smaller drill bit to reduce heat accumulation and material stress. Since the small drill bit is used, the material bearing force during the penetration process is smaller, and the impact and possible offset during penetration can be reduced.

[0019] As a further improvement of the present invention, when the drilling distance of the drilling on both sides is 10%-20% of the inner hole depth, the drill bit with a smaller diameter is replaced.

[0020] As a further improvement of the present invention, the feed rate of the drill bit with a smaller diameter is 30%-50% of the feed rate of the drill bit with the original size, which can reduce the pressure and heat generated by rapid drilling and better ensure the accuracy of the inner hole forming.

[0021] As a further improvement of the present invention, when replacing the drill bit with a smaller diameter to break through, a small amplitude of drilling and retracting is adopted, which helps to remove chips and reduce the pressure on the drilling wall. At the same time, it can also reduce the drill bit deviation or hole wall damage caused by the sudden release of the pressure of the material being drilled during breakthrough.

[0022] As a further improvement of the present invention, the diameter of the drill bit with a smaller diameter should be at least 5 mm smaller than the diameter of the drill bit with the original size, so as to leave enough gaps for the circulation of the coolant when the drilling at both ends is close to breakthrough, and ensure the accuracy of the final hole diameter. The sufficient gap can promote the effective flow of the coolant, help to control the temperature during the processing, reduce the thermal stress and improve the processing quality. It also avoids excessive impact or material deformation during the final breakthrough. At the same time, after reprocessing with the large drill bit finally, it can effectively correct any tiny deviation caused by the processing with the small drill bit and ensure the accuracy of the hole diameter and the surface finish.

[0023] As a further improvement of the present invention, after step S4, laser polishing technology is used to perform ultra-precision machining on the inner hole surface to further improve the surface finish, and the laser polishing technology is pulsed or continuous wave laser.

[0024] As a further improvement of the present invention, 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 unevenness.

[0025] 3. Beneficial effects

[0026] The present invention first uses a large drill bit for preliminary drilling to quickly remove most of the material, which can improve the initial drilling speed and efficiency. When the drill holes at both ends are about to approach each other, the use of the large drill bit is paused, and a small drill bit is replaced. The use of the small drill bit can leave more adjustment space and material for the next steps for final forming. During the process of fine drilling with the small drill bit, the flow rate of the coolant can be increased around the drill hole, and the gap left by the smaller drill bit is utilized to improve the cooling effect, reduce heat accumulation and material stress. Since the small drill bit is used, the material bearing capacity during the drilling process is smaller, which can reduce the impact and possible deviation during breakthrough. At the same time, after finally reprocessing with the large drill bit, any minor deviations caused by the processing of the small drill bit can be effectively corrected to ensure the accuracy of the hole diameter and the surface finish. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a process flow chart of the present invention;

[0028] Figure 2 is a data table for the detection of the inner hole quality of Embodiments 1-4 and the control example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention; obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] Embodiment 1:

[0031] A process for machining the inner hole of a speed reducer housing includes the following steps:

[0032] S1. Select a cast iron material to make the speed reducer housing;

[0033] S2. The inner hole has a diameter of 30 mm and a depth of 50 mm. Select a CNC milling machine to rough machine the inner hole to remove most of the surplus. When rough machining, the method of synchronous drilling on both sides of the inner hole is adopted, and the diameter of the original size drill bit is 28 mm;

[0034] S3. During the drilling process, ensure the centering accuracy of the drill holes on both sides in real time until the drilling is completed and the hole is broken through. When the drill holes on both sides are about to be broken through, pause, replace the drill bit with a diameter of 22 mm to break through, and inject coolant into the inner hole. After breaking through, replace the original size drill bit to perform final machining on the inner hole to ensure the consistency of the hole diameter and the surface smoothness. Replace the 22-mm drill bit when the drilling distance 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, and the method of small amplitude drilling and retracting is adopted;

[0035] S4. After drilling through, use a high-precision CNC internal grinding machine to finish machining the inner hole to achieve the required precision and surface finish, and use continuous-wave laser polishing technology to super-finish the inner hole surface to further improve the surface finish.

[0036] S5. Clean the inner hole to remove all chips and contaminants generated during the machining process, and then perform a final quality inspection. The quality inspection includes dimensional inspection and surface inspection. Dimensional inspection includes the diameter, depth, and position accuracy of the inner hole, and surface inspection includes cracks, scratches, and unevenness.

[0037] Example 2:

[0038] A machining process for the inner hole of a speed reducer housing includes the following steps:

[0039] S1. Select cast iron material to make the speed reducer housing.

[0040] S2. The inner hole has a diameter of 30 mm and a depth of 50 mm. Select a CNC milling machine to rough-machine the inner hole to remove most of the surplus. When rough-machining, use the method of synchronous drilling on both sides of the inner hole. The diameter of the original-size drill bit is 28 mm.

[0041] S3. During the drilling process, ensure the centering accuracy of the drilling on both sides in real time until the drilling is completed and through. When the drilling on both sides is close to being through, pause, replace the drill bit with a diameter of 20 mm to drill through, and inject coolant into the inner hole. After drilling through, replace the original-size drill bit to perform the final machining of the inner hole to ensure the diameter consistency and surface smoothness. Replace the drill bit with a diameter of 20 mm when the drilling distance 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, and use the method of small-amplitude drilling and retraction.

[0042] S4. After drilling through, use a high-precision CNC internal grinding machine to finish machining the inner hole to achieve the required precision and surface finish, and use continuous-wave laser polishing technology to super-finish the inner hole surface to further improve the surface finish.

[0043] S5. Clean the inner hole to remove all chips and contaminants generated during the machining process, and then perform a final quality inspection. The quality inspection includes dimensional inspection and surface inspection. Dimensional inspection includes the diameter, depth, and position accuracy of the inner hole, and surface inspection includes cracks, scratches, and unevenness.

[0044] Example 3:

[0045] A machining process for the inner hole of a speed reducer housing includes the following steps:

[0046] S1. Select cast iron material to make the speed reducer housing.

[0047] S2. The inner hole has a diameter of 30 mm and a depth of 50 mm. Select a CNC milling machine to rough machine the inner hole to remove most of the surplus. When rough machining, the method of synchronous drilling on both sides of the inner hole is adopted, and the diameter of the original size drill bit is 28 mm;

[0048] S3. During the drilling process, ensure the centering accuracy of the drilling on both sides in real time until the drilling is completed and the hole is penetrated. When the drilling on both sides is close to penetration, pause, replace the drill bit with a diameter of 18 mm to penetrate the hole, and inject coolant into the inner hole. After penetration, replace the original size drill bit to perform the final machining of the inner hole to ensure the diameter consistency and surface smoothness. Replace the 18 mm drill bit when the drilling distance 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, and the method of small amplitude drilling and retracting is adopted;

[0049] S4. After penetration, use a high-precision CNC internal grinding machine to finish machine the inner hole to achieve the required accuracy and surface finish, and use the continuous wave laser polishing technology to perform super-finishing on the inner hole surface to further improve the surface finish;

[0050] S5. Clean the inner hole to remove all chips and contaminants generated during the machining process, and then perform 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 unevenness.

[0051] Example 4:

[0052] A processing technology for the inner hole of a speed reducer housing includes the following steps:

[0053] S1. Select a cast iron material to make the speed reducer housing;

[0054] S2. The inner hole has a diameter of 30 mm and a depth of 50 mm. Select a CNC milling machine to rough machine the inner hole to remove most of the surplus. When rough machining, the method of synchronous drilling on both sides of the inner hole is adopted, and the diameter of the original size drill bit is 28 mm;

[0055] S3. During the drilling process, ensure the centering accuracy of the drilling on both sides in real time until the drilling is completed and the hole is penetrated. When the drilling distance on both sides is 10% of the inner hole depth, adjust the feed rate to 30% of the original feed rate, and adopt the method of small amplitude drilling and retracting;

[0056] S4. After penetration, use a high-precision CNC internal grinding machine to finish machine the inner hole to achieve the required accuracy and surface finish, and use the continuous wave laser polishing technology to perform super-finishing on the inner hole surface to further improve the surface finish;

[0057] S5. Clean the inner hole, remove all the chips and contaminants 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 unevenness.

[0058] Comparative example:

[0059] A processing technology for the inner hole of a speed reducer housing includes the following steps:

[0060] S1. Select a cast iron material to make the speed reducer housing;

[0061] S2. The inner hole has a diameter of 30 mm and a depth of 50 mm. Select a CNC milling machine to rough-machine the inner hole to remove most of the surplus. The diameter of the original-size drill bit is 28 mm;

[0062] S3. Use a high-precision CNC internal grinder to finish-machine the inner hole to achieve the required precision and surface finish. Use the continuous-wave laser polishing technology to super-finish the inner hole surface to further improve the surface finish;

[0063] S4. Clean the inner hole, remove all the chips and contaminants 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 unevenness.

[0064] Please refer to Figure 2 , Examples 1, 2, and 3 show that the use of a small-diameter drill bit and coolant can significantly improve the accuracy (tolerance ±0.01 mm), compared with Example 4 (tolerance ±0.03 mm) without using a small drill bit and the comparative example (tolerance ±0.05 mm). This indicates that the use of a small drill bit helps to control the precision and stability during the processing. The examples using a small-diameter drill bit (Examples 1, 2, and 3) obtain a lower surface roughness (0.5 - 0.8 microns), while Example 4 without using a small-diameter drill bit has a higher surface roughness (1.1 microns), almost close to the surface roughness of the comparative example (1.4 microns). This proves that the small-diameter drill bit is beneficial to improving the surface quality during the drilling and retracting processes. And it is found during the implementation that in the surface quality inspection of the inner hole formed by the processing of Examples 1, 2, and 3, cracks, scratches, and deformation rarely occur, while the frequency of the above situations is relatively high in the ordinary processing. It can be seen that the method of drilling from both sides and then modifying a small-diameter drill bit to break through can improve the stability of the inner hole forming.

[0065] It should be noted that the process parameters of the finish machining and super-finishing of Examples 1 - 4 and the comparative example are exactly the same to reduce the influence of the drilling process on the inner hole forming result.

[0066] The above is only a preferred specific embodiment of the present invention; however, the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its improved concept, making equivalent substitutions or changes, 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. Select materials 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 close to being drilled through, the process is paused, and a small-diameter drill is replaced to drill through. Coolant is injected into the inner hole. After drilling through, the original-size drill is replaced to perform final processing on the inner hole to ensure the consistency of the hole diameter and smooth surface. When replacing the small-diameter drill to drill through, a small-amplitude drilling and retreating method is adopted. The diameter of the small-diameter drill should be at least 5 mm smaller than the diameter of the original-size drill, so as to leave enough gaps for the circulation of coolant when the holes on both ends are close to being drilled through, and to ensure the accuracy of the final hole diameter. 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 generated during the processing, and then conduct the final quality inspection; The material is one of cast iron or aluminum alloy.

2. A process for machining inner holes of a reducer housing according to claim 1, 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.

3. 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.

4. A process for machining inner holes of a reducer housing according to claim 1 or 3, 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.

5. 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.

6. 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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