A step-type high-precision small-diameter deep-hole shell processing method and tool

Abstract

The present invention discloses a processing method and a processing tool for a stepped high-precision small-diameter deep-hole shell. The processing method comprises the following steps: fixing the cylindrical bar to be processed in the front and rear jackets of a CNC Swiss-type machine tool, and drilling the first circular hole, the second circular hole, and the second circular hole in sequence, and then using the processing tool of the present invention to fine-boring the entire stepped hole cavity, the processing tool is kept axially stationary at the nearest end of the front jacket, and the rear jacket drives the bar to move to one side of the processing tool, and then the part shape structure is processed, and the processing is completed after cutting. The present invention also provides a processing tool for a stepped high-precision small-diameter deep-hole shell. The present invention ensures that the processing of high coaxial precision holes can be achieved, and meets the technical requirements of high coaxiality accuracy of the product.

Description

Technical Field

[0001] The invention relates to the field of mechanical processing, and in particular to a processing method and a tool for a stepped high-precision small-diameter deep-hole shell. Background Art

[0002] Stepped high-precision small diameter deep hole shell ( Figure 1 ) is designed with high precision, the difficulty lies in how to ensure the minimum aperture The processing depth of 18.6±0.1mm is qualified. At the same time, the small hole and the two stepped holes are required to be The coaxiality between the outer circles is guaranteed to be within Φ0.005mm. Our factory has no precedent for processing such a high coaxiality, and it is difficult to break through in technology. In addition, due to the difficulty of chip removal and insufficient cooling, in traditional process planning, the processing tasks of the inner holes are mostly left to the second process. The most suitable processing method is: the first process processes the minimum hole and the outer size, and the second process is to clamp the outer circle of the part by the CNC lathe, process two stepped holes, and finally complete the processing of the part. However, the traditional processing plan is not suitable for the processing of this part, because the aperture processed by the secondary clamping is difficult to ensure high coaxiality with the outer circle of the part processed by the first process.

[0003] It is difficult to complete all the processes of machining parts from one end of the large hole using existing tools. The material of the part is stainless steel rod, which is difficult to process. If such a deep hole is processed with a drill bit alone, it will be difficult to ensure the roughness of more than 0.8 and the tolerance of 0.01 required for processing. Moreover, due to the swing of the drill bit, it is difficult for the drill tip to remain at the center point of such a deep hole. Once there is an offset, the center will become more and more offset as the hole is drilled deeper. Therefore, only the combination of drilling and boring can complete the processing. The cutting part diameter of the traditional boring tool can only be less than 2.4mm and 20mm long. Such a thin boring tool will produce a "cutting" phenomenon due to insufficient rigidity. As a result, the straight hole becomes a slightly hole.

[0004] Therefore, a processing method and a processing tool are needed that can ensure that the minimum hole diameter is qualified and the coaxiality meets the requirements. Summary of the invention

[0005] The technical problem solved by the present invention is to propose a method for ensuring the minimum aperture The processing depth of 18.6±0.1mm is qualified, and the small hole and the two stepped holes meet the requirements. The coaxiality between the outer circles is guaranteed to be within Φ0.005mm for the processing method and tool of the stepped high-precision small-diameter deep-hole shell.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for processing a stepped high-precision small-diameter deep-hole shell, the stepped high-coaxial precision small-diameter deep-hole shell comprising a shell body, a stepped hole consisting of a first circular hole, a second circular hole, and a third circular hole are coaxially arranged in sequence inside the shell body, characterized in that the method comprises the following steps:

[0008] (1) The cylindrical bar to be processed is fixed in the front and rear jackets of the CNC machine tool, the front jacket is controlled to remain axially stationary, the cylindrical bar passes through the front jacket and fits with the inner wall of the front jacket, and the rear jacket clamps the cylindrical bar and drives the cylindrical bar to move axially;

[0009] (2) First, a carbide twist drill is used to perform the first round hole processing step, with a machine speed of 2000 rpm and a feed speed of 0.01 mm / rev;

[0010] (3) Then, a carbide twist drill is used to process the second circular hole at a speed of 2000 rpm and a feed rate of 0.02 mm / rev.

[0011] (4) At the bottom of the second circular hole that has been formed, use a variable diameter carbide drill bit to continue drilling the third circular hole at a speed of 1500 rpm and a feed speed of 0.02 mm / rev;

[0012] (5) The entire stepped hole cavity is finely bored using the machining tool of the present invention, the machining tool is kept axially immobile at the nearest end of the front jacket, and the rear jacket drives the bar to move toward the side of the machining tool. The machining tool has a rotation speed of 1500 rpm and a feed speed of 0.01 mm / rev.

[0013] (6) The rear collet drives the bar to move toward the side of the processing tool to realize the tool withdrawal action;

[0014] (7) The external cylindrical cutter is adjusted to the processing position to process the external structure of the part at a speed of 2000 rpm and a feed speed of 0.02 mm / rev;

[0015] (8) The machine tool's secondary spindle clamps the front end of the part to assist in cutting, preventing the part from falling off and causing damage to the machine tool after cutting. The machine tool then feeds the tool vertically downward to complete the cutting. The secondary spindle carries the part back and places the part in a collection box to complete the processing.

[0016] Furthermore, after the first circular hole, the second circular hole and the third circular hole are roughly processed in steps (2), (3) and (4), a cutting amount of 0.1 mm is reserved on one side.

[0017] Furthermore, in step (5), the tool tip of the machining tool is located about 1 mm from the front end of the front jacket for boring.

[0018] A stepped high-precision small-diameter deep-hole shell processing tool, the processing tool comprises a coaxially arranged and integrally formed tool handle, a tool rod and a blade, the tool handle is a stepped cylindrical type composed of a first cylinder and a second cylinder, the tool rod is a cylindrical type, the front end of the tool rod is a blade, a transition bevel is provided at the connection between the tool rod and the blade, the blade comprises a rake face, a main cutting edge, and a secondary cutting edge, the front edge of the rake face is a straight main cutting edge, a straight secondary cutting edge protruding outward is provided above the rake face, the top of the main cutting edge intersects with the front end of the secondary cutting edge, the angle α between the main cutting edge and the vertical plane is 5°, the main deflection angle β of the main cutting edge is 95°, the front angle λ and the back angle θ are both 7°, the secondary deflection angle δ of the secondary cutting edge is 2°,

[0019] Further, the diameter D1 of the first cylinder is greater than the diameter D2 of the second cylinder, and the diameter D2 of the second cylinder is greater than the diameter D3 of the shank.

[0020] Furthermore, the diameter D1 of the first cylinder is 4 mm, the diameter D2 of the second cylinder is 3.75±0.01 mm, and the diameter D3 of the shank is 2.19 mm to 2.20 mm.

[0021] Furthermore, the axial length L1 of the first cylinder is 20mm±0.2mm, the axial length L2 of the second cylinder is 2.5mm~2.7mm, the distance L3 between the vertical plane where the end face of the shank intersects the main cutting edge and the secondary cutting edge of the blade is 8.5mm~8.8mm, and the axial length L4 of the front cutting edge is 3.0~3.3mm.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention independently designs a stepped boring tool by analyzing the stepped structure inside the hole cavity. The tool handle of the machining tool is stepped, which effectively avoids interference during cutting and maximizes the rigidity of the boring tool. At the same time, the tool adopts a larger rake angle to reduce cutting deformation and cutting force, further ensuring the stability of the boring process, so that it can withstand greater cutting torque without bending or vibration, ensuring that the machining of high coaxial precision holes can be achieved and meeting the technical requirements of high coaxiality accuracy of the product.

[0024] (2) The present invention adopts a process method of clamping all the parts processing steps at one time, which ensures high dimensional accuracy and high coaxiality requirements. The present invention adopts a Swiss-type lathe for turning. Turning is a rotating body processing. When the machine tool clamps the material and rotates, the center point of rotation is generated. At this time, all turning processes performed on the material are performed around the same rotation center point. Therefore, after clamping the part, the center of rotation remains unchanged when turning the outer circle and boring the inner hole. The processed parts will naturally ensure high coaxiality. At the same time, compared with ordinary turning equipment, the Swiss-type lathe passes the material through the spindle through hole, and the spring chuck automatically clamps the bar. The Swiss-type lathe does not need to extend the material in advance. When cutting, the tool always cuts at the position closest to the front sleeve of the spindle. This position is the position with the best rigidity of the material. Cutting at the position with the best rigidity further ensures the high coaxiality requirements of the part. The present invention can complete the processing without the help of high-precision and cutting-edge equipment. The cost is low and the effect is significant. The processing method and processing tool of the present invention can ensure the minimum hole diameter The processing depth of 18.6±0.1mm is qualified, and the small hole and the two stepped holes meet the requirements. The coaxiality between the outer circles is guaranteed to be within Φ0.005mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of a stepped high coaxial precision small diameter deep hole housing processed by an embodiment of the present invention;

[0026] Figure 2 It is a schematic diagram of processing of a cylindrical bar of the present invention;

[0027] Figure 3 It is a schematic diagram of the structure of the machining tool of the present invention;

[0028] Figure 4 It is a structural schematic diagram of the front angle and the back angle of the machining tool of the present invention;

[0029] Figure 5 It is a schematic diagram of the use of the processing tool of the present invention;

[0030] In the figure:

[0031] 1-housing body; 2-first circular hole; 3-second circular hole; 4-third circular hole; 5-front jacket; 6-rear jacket; 7-cylindrical bar; 8-processing tool; 81-tool handle; 811-first cylinder; 812-second cylinder; 82-tool bar; 821-transition slope; 83-blade; 831-front cutting face; 832-main cutting edge; 833-secondary cutting edge; DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0033] Example 1

[0034] Reference Figure 1 The structure of the pre-processed stepped high coaxial precision small diameter deep hole shell of the present invention is as follows Figure 1 As shown, it includes a shell body 1, and a stepped hole consisting of a first circular hole 2 and a second circular hole 3 and a third circular hole 4 are coaxially arranged in sequence inside the shell body 1. The aperture of the first circular hole 2 is The diameter of the second circular hole 3 is The diameter of the third circular hole 4 is The axial length L5 of the shell body is 18.6±0.1 mm.

[0035] Reference Figure 2 The present invention provides a method for processing a stepped high-precision small-diameter deep-hole shell, the method comprising the following steps:

[0036] (1) A cylindrical bar 7 to be processed is fixed in the front jacket 5 and the rear jacket 6 of a CNC machine tool, the front jacket 5 is controlled to remain axially stationary, the cylindrical bar 7 passes through the front jacket 5 and fits with the inner wall of the front jacket 5, and the rear jacket 6 clamps the cylindrical bar 7 and drives the cylindrical bar 7 to move axially;

[0037] (2) First, a Φ4.8 mm carbide twist drill is used to perform the first round hole 2 processing step, with a machine speed of 2000 rpm and a feed speed of 0.01 mm / rev;

[0038] (3) Then, a Φ4.8 mm carbide twist drill is used to process the second circular hole 3 at a speed of 2000 rpm, a feed speed of 0.02 mm / rev, and a processing depth of 10.5 mm;

[0039] (4) At the bottom of the second circular hole 3 that has been formed, use a φ2.4mm reduced diameter carbide drill to continue drilling the third circular hole 4, with a rotation speed of 1500 rpm, a feed speed of 0.02mm / rev, and a processing depth of 19.5mm;

[0040] (5) The machining tool 8 (stepped alloy boring tool) of the present invention is used to finely bore the entire step hole cavity. The machining tool 8 is kept axially immobile at the nearest end of the front jacket 5, and the rear jacket 6 drives the bar to move toward the side of the machining tool 8. The machining tool has a rotation speed of 1500 rpm and a feed speed of 0.01 mm / rev. The aperture of the first circular hole 2 after machining is The diameter of the second circular hole 3 is The diameter of the third circular hole 4 is

[0041] (6) The rear clamping sleeve 6 drives the bar to move to the right, realizing the tool withdrawal action;

[0042] (7) The external cylindrical cutter is adjusted to the processing position to process the external structure of the part at a speed of 2000 rpm and a feed speed of 0.02 mm / rev;

[0043] (8) The machine tool sub-spindle clamps the front end outer circle of the part to assist in cutting to prevent the part from falling off and causing damage to the machine tool after cutting. Then the tool is fed vertically downward to complete the cutting. After cutting, the axial length L5 of the shell body is 18.6±0.1mm. The sub-spindle carries the part back and places the part in the collection box to complete the processing.

[0044] After the first circular hole 2, the second circular hole 3 and the third circular hole 4 are roughly machined in steps (2), (3) and (4), a cutting allowance of 0.1 mm is reserved on one side.

[0045] In the step (5), the tip of the machining tool is located at about 1 mm from the front end of the front jacket 5 for boring.

[0046] A stepped high-precision small-diameter deep-hole shell processing tool, the processing tool comprises a coaxially arranged and integrally formed tool handle 81, a tool rod 82 and a blade 83, the tool handle 81 is a stepped cylindrical type composed of a first cylinder 811 and a second cylinder 812, the tool rod 82 is a cylindrical type, the front end of the tool rod 82 is a blade 83, the connection between the tool rod 82 and the blade 83 is provided with a transition slope 821, the blade 83 comprises a rake face 831, a main cutting edge 832 , a secondary cutting edge 833, the front edge of the rake face 831 is a straight main cutting edge 832, a straight secondary cutting edge 833 protruding outward is provided above the rake face 831, the top of the main cutting edge 832 intersects with the front end of the secondary cutting edge 833, the angle α between the main cutting edge 832 and the vertical plane is 5°, the main deflection angle β of the main cutting edge 832 is 95°, the front angle λ and the back angle θ are both 7°, and the secondary deflection angle δ of the secondary cutting edge 833 is 2°,

[0047] The diameter D1 of the first cylinder 811 is greater than the diameter D2 of the second cylinder 812 , and the diameter D2 of the second cylinder 812 is greater than the diameter D3 of the knife rod 82 .

[0048] The diameter D1 of the first cylinder 811 is 4 mm, the diameter D2 of the second cylinder 812 is 3.75±0.01 mm, and the diameter D3 of the shank is 2.19 mm to 2.20 mm.

[0049] The axial length L1 of the first cylinder 811 is 20mm±0.2mm, the axial length L2 of the second cylinder 812 is 2.5mm~2.7mm, the distance L3 between the end face of the shank 82 and the vertical plane where the main cutting edge 832 and the secondary cutting edge 833 of the blade 83 intersect is 8.5mm~8.8mm, and the axial length L4 of the front cutting edge 831 is 3.0~3.3mm.

[0050] The stepped structure of the tool handle 81 of the machining tool matches the stepped inner cavity structure of the housing body 1. As the cutting progresses, a single-side 0.2 mm gap is formed between the tool and the hole wall for chip removal (such as Figure 5 As shown in FIG. 8 , the rest of the hole is filled with the tool, which ensures the rigidity of the boring tool to the greatest extent and avoids the problem of interference caused by the tool handle 81 being too thick.

[0051] Working principle of the present invention: In terms of improvement of machining tools, we choose to drill the bottom hole first and then fine bore the inner hole. After the drill drills the hole, there will be a small amount of center offset, and boring processing belongs to the form of single-sided cutting, which plays a corrective role for the slightly offset center hole. However, the pin cutter for boring small holes is not rigid enough and is easy to get out of the way. It is necessary to design a boring cutter with more rigidity to make up for this shortcoming. The machining tool of the present invention effectively avoids interference during cutting and enhances the rigidity of the boring cutter to the greatest extent. At the same time, the tool adopts a larger rake angle to reduce cutting deformation and cutting force, further ensuring the stability of the boring process, so that it can withstand a larger cutting torque without bending or vibration, ensuring that the processing of high coaxial precision holes can be achieved, and meeting the technical requirements of high coaxiality accuracy of the product.

[0052] The present invention adopts a process method of clamping all the processes of processing parts at one time, which ensures high dimensional accuracy and high coaxiality requirements. The present invention adopts a Swiss-type lathe for turning. Turning is a rotating body processing. When the machine tool clamps the material and rotates, the center point of rotation is generated immediately. At this time, all turning processes performed on the material are performed around the same rotation center point. Therefore, after clamping the parts, the center of rotation remains unchanged when turning the outer circle and boring the inner hole. The processed parts will naturally ensure high coaxiality. At the same time, compared with ordinary turning equipment, the Swiss-type lathe passes the material through the spindle through hole, and the spring chuck automatically clamps the bar. The Swiss-type lathe does not need to extend the material in advance. When cutting, the tool always cuts at the position closest to the front sleeve of the spindle. This position is the position with the best rigidity of the material, and cutting is always carried out at the position with the best rigidity, which further ensures the high coaxiality requirements of the parts.

[0053] The CNC Swiss-type lathe equipment used in the present invention is a CNC longitudinal cutting processing center of Hanhua Company, model: XP12.

[0054] The present invention solves the disadvantage of the prior art that multiple processing steps of parts produce positioning errors and cannot meet the high coaxiality requirements of the product. By designing processing tools and using precision Swiss-type machine tools to turn and process parts, the present invention adopts a process method that clamps all the processing steps of the parts at one time. While ensuring high dimensional accuracy, it also ensures high coaxiality requirements. The shell processed by the present invention can ensure the minimum aperture The processing depth of 18.6±0.1mm is qualified, and the small hole and the two stepped holes meet the requirements. The coaxiality between the outer circles is guaranteed to be within Φ0.005mm.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for processing a stepped high-precision small-diameter deep-hole shell, the stepped high-precision small-diameter deep-hole shell comprising a shell body, a stepped hole consisting of a first circular hole, a second circular hole, and a third circular hole are coaxially arranged in the shell body, characterized in that: The processing method comprises the following steps: (1) The cylindrical bar to be processed is fixed in the front and rear jackets of the CNC machine tool, the front jacket is controlled to remain axially stationary, the cylindrical bar passes through the front jacket and fits with the inner wall of the front jacket, and the rear jacket clamps the cylindrical bar and drives the cylindrical bar to move axially; (2) First, use a carbide twist drill to perform the first round hole processing step, the machine tool speed is 2000 rpm, and the feed speed is 0.01 mm / rev; (3) Then use a carbide twist drill to process the second circular hole at a speed of 2000 rpm and a feed speed of 0.02 mm / rev. (4) At the bottom of the second circular hole that has been formed, use a variable diameter carbide drill to continue drilling the third circular hole at a speed of 1500 rpm and a feed speed of 0.02 mm / rev; (5) Use the machining tool to fine bore the entire stepped hole. The machining tool is kept axially immobile at the nearest end of the front jacket, and the rear jacket drives the bar to move toward the side of the machining tool. The machining tool speed is 1500 rpm and the feed speed is 0.01 mm / rev. The machining tool comprises a coaxially arranged and integrally formed tool handle, a tool rod and a blade, the tool handle is a stepped cylindrical body composed of a first cylinder and a second cylinder, the tool rod is a cylindrical body, the front end of the tool rod is a blade, a transition bevel is provided at the connection between the tool rod and the blade, the blade comprises a rake face, a main cutting edge and a secondary cutting edge, the front edge of the rake face is a straight main cutting edge, a straight secondary cutting edge protruding outward is provided above the rake face, the top of the main cutting edge intersects with the front end of the secondary cutting edge, the angle α between the main cutting edge and the vertical plane is 5°, the main deflection angle β of the main cutting edge is 95°, the rake angle λ and the back angle θ are both 7°, and the secondary deflection angle δ of the secondary cutting edge is 2°; (6) The rear collet drives the bar to move away from the processing tool, realizing the tool withdrawal action; (7) The external cylindrical cutter is adjusted to the processing position to process the external structure of the part at a speed of 2000 rpm and a feed speed of 0.02 mm / rev. (8) The machine tool sub-spindle clamps the front end outer circle of the part to assist in cutting, preventing the part from falling off and causing damage to the machine tool after cutting. Then the tool is fed vertically downward to complete the cutting. The sub-spindle carries the part back and places the part in the collection box to complete the processing.

2. A method for processing a stepped high-precision small-diameter deep-hole shell as claimed in claim 1, characterized in that: After the first circular hole, the second circular hole and the third circular hole are roughly machined in steps (2), (3) and (4), a cutting allowance of 0.1 mm is reserved on one side.

3. A method for processing a stepped high-precision small-diameter deep-hole shell as claimed in claim 1, characterized in that: In the step (5), the tip of the machining tool is located about 1 mm from the front end of the front jacket for boring.

4. A method for processing a stepped high-precision small-diameter deep-hole shell as claimed in claim 1, characterized in that: The diameter D1 of the first cylinder is greater than the diameter D2 of the second cylinder, and the diameter D2 of the second cylinder is greater than the diameter D3 of the shank.

5. A method for processing a stepped high-precision small-diameter deep-hole shell as claimed in claim 1, characterized in that: The diameter D1 of the first cylinder is 4 mm, the diameter D2 of the second cylinder is 3.75±0.01 mm, and the diameter D3 of the shank is 2.19 mm-2.20 mm.

6. A method for processing a stepped high-precision small-diameter deep-hole shell as claimed in claim 1, characterized in that: The axial length L1 of the first cylinder is 20mm±0.2mm, the axial length L2 of the second cylinder is 2.5mm-2.7mm, the distance L3 between the end face of the shank and the vertical plane where the main cutting edge and the secondary cutting edge of the blade intersect is 8.5mm-8.8mm, and the axial length L4 of the front cutting edge is 3.0-3.3mm.

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