Machining method for rifling of main cylinder body

Abstract

The invention relates to a main cylinder body rifling machining method, and belongs to the field of automobile brake main cylinder body machining. Mounting a main cylinder body on a clamp, quickly moving a cutter to a zero point position of a part coordinate, quickly moving the cutter to a second leather cup groove along a negative direction of a Z axis, performing linear interpolation from the center of the second leather cup groove along a positive direction of an X axis, cutting a cutter tip into a main hole wall, performing arc feed milling by taking the part coordinate as a center, and finishing rifling machining. The method has the advantages that calculation and modification of end point coordinates are convenient, the program amount is particularly small, the method can be suitable for machining of multiple products, the machining efficiency is high, multiple procedures such as vertical hole machining, eccentric groove machining and flange hole machining can be achieved while rifling machining is conducted, the machining range is wider, adaptability is higher, and the method is suitable for large-scale popularization and application. And machining can be conducted at any position and any angle in the hole, practicability is good, and the popularization prospect is achieved.

Description

Technical Field

[0001] The invention belongs to the field of automobile brake master cylinder processing, and in particular relates to a method for processing the rifling of the master cylinder. Background Art

[0002] The brake master cylinder is the core part of the entire brake. It is the part with the highest machining precision and the most complex process among all the parts of the brake. Due to the process requirements, the plunger master cylinder needs to have two rifling grooves machined on its hole wall. Its function is to ensure the movement trajectory of the internal piston. The required curved surface of the part must fit on the main hole wall of the master cylinder. The surface finish must be above 1.6, and there must be no flash or burrs. The quality of the rifling seriously affects the braking effect of the car brake and has a great impact on the driving safety of the driver.

[0003] At present, most domestic and foreign companies generally use broaches to process the main hole rifling. When performing such processing, the tool can only process rifling of fixed diameter size, and the depth of the rifling is controlled by the size of the tool. The processing process cannot control the processing curve trajectory of the tool. When the size of the main hole of the product changes or the angle of the rifling needs to be adjusted, the processing disadvantages of the broach become prominent, and it cannot meet the processing requirements of multiple varieties. At the same time, the tool cost is greatly increased, and the positioning accuracy of the processing during the processing is also required to be high. Since domestic and foreign automobile companies have hundreds of models to supply, the processing size and processing position of each model product are also different. Therefore, it is necessary to develop a main cylinder rifling processing method with low tool cost, simple fixture manufacturing process, low cost, low investment, low maintenance cost, economical and applicable, and easy adjustment. Summary of the invention

[0004] The invention provides a method for machining the rifling of a main cylinder body, so as to solve the problems of high tool cost, complex fixture manufacturing process, high cost and inconvenient adjustment existing in the process of using a broach.

[0005] The technical solution adopted by the present invention comprises the following steps: Step 1: Install the main cylinder body on the fixture. The rifling of the main cylinder body is divided into two sections. The center of the tool tip is used as the programming reference. Radius compensation needs to be applied during processing. Step 2: Quickly move the tool to the zero point of the part coordinates; Step 3: Move the tool quickly along the negative direction of the Z axis to the second cup groove; Step 4: Linear interpolation is performed from the center of the second cup groove along the positive direction of the X axis, and the tool tip cuts into the main hole wall. The X axis movement value is the radius value of the main hole; Step 5: The tool starts from the end point of the fourth step and uses the part coordinates as the center for arc milling. Since the tool feed direction is counterclockwise, counter-circular arc interpolation is used. During the arc feed, the Z axis needs to feed linearly in the negative direction to the second empty tool groove. The X-axis and Y-axis end point coordinates need to be calculated by functions. Step 6: The tool is retracted linearly to the center of the main hole, and the tool radius compensation is canceled. The first rifling is processed and the second rifling is processed in the same way. Step 7. After processing is completed, the tool quickly moves outside the part along the positive direction of the Z axis and the program ends.

[0006] The method for installing the main cylinder body on the fixture in step 1 of the present invention is as follows: Relying on the flange surface and positioning holes of the main cylinder body, plus the outer circle of the part head, a two-pin positioning is formed on one side to ensure that the center position of the part is fixed. The height of the fixture covers all the processing requirements of the cylinder body. The bushing of the upper fixture cover can be replaced to meet the processing requirements of parts with different outer circles. The locking device at the bottom performs linear up and down movement to complete the clamping of the part. There is a threaded hole in the middle of the locking device, and the threaded hole can be installed with various lengths and types of tops. This set of fixtures is highly flexible and can meet the needs of different types of products. Secondly, this set of fixtures is small in size and does not take up space.

[0007] The processing tool in step 1 of the present invention is a carbide milling cutter, and the tool has a front angle of 15°-20° and a back angle of 15°-20°.

[0008] The calculation method in step 5 of the present invention is as follows: The first known condition is that the tool moves along the main hole wall in an arc and the feed radius is the radius r of the main hole of the part; Known Condition 2: The feed distance of the Z axis of the tool is the distance L from the second cup groove to an empty groove; Known conditions: The helix angle α of the three-rifling groove; When writing a program, first calculate the distance b that the tool travels when it makes an arc feed on the hole wall. Secondly, calculate the opposite side of a right triangle with an angle of α. The adjacent side is the Z-axis feed distance L, b=tanα×L, which is the length of the arc that the tool travels when it makes an arc feed. The circumference of the main hole is C, the arc angles of the X-axis and Y-axis end points β=b / C×360, the X-axis end point coordinates are x=cosβ×r, and the Y-axis end point coordinates are y=sinβ×r. In this way, the X-axis and Y-axis end point coordinates are obtained. When the diameter of the main hole changes, the radius compensation of the tool can be modified. When the main hole increases, the radius compensation decreases. When the main hole decreases, the tool radius can be increased.

[0009] In step five of the present invention, the processing parameters are a rotation speed of 5000 r / min, a feed speed of 100 mm / min, and a cutting depth of 0.3 mm.

[0010] The advantages of the present invention are the calculation of the end point coordinates, and the modification is convenient, and the program volume is particularly small. Traditional processing of such complex surfaces mostly uses software programming, but the program modification is difficult. When the tool processing trajectory is high, the program volume is large and the pause is obvious. However, when the processing accuracy is lowered, the program volume is reduced, but the processing trajectory becomes larger and the smoothness cannot meet the process requirements. When the product is replaced, the program must be rewritten, and multiple inspections and test cuts are required. The present invention can adapt to the processing of multiple products. Regardless of any adjustments and changes in the size of the aperture and the processing position, it can be easily dealt with, and the processing efficiency is very high. It can process multiple processes such as vertical holes, eccentric grooves and flange holes while processing rifling; the fixture used is relatively small and does not take up space, the tool cost is low, the tool life is long, and the processing size is stable. A rifling tool can process more than 20,000 pieces. Compared with the rifling broach, the present invention has a wider processing range and stronger adaptability. It can be processed at any position and angle in the hole. It has good practicality and has a promotion prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a structural schematic diagram of the main cylinder body processed by the present invention; Figure 2 It is a schematic diagram of the structure of the processing fixture of the present invention cooperating with the main cylinder body; Figure 3 It is a structural schematic diagram of a machining tool of the present invention; Figure 4 It is a schematic diagram of the machining tool of the present invention being located at the zero point position of the part coordinate; Figure 5 is a schematic diagram of the present invention when it is rapidly moved to the second leather cup groove along the negative direction of the Z axis; Figure 6 It is a schematic diagram of the present invention when the tip of the knife cuts into the main hole wall; Figure 7 It is a schematic diagram of the tool of the present invention milling with the part coordinate as the center arc feed; Figure 8 It is a schematic diagram of the present invention when the tool is linearly withdrawn to the center position of the main hole. DETAILED DESCRIPTION

[0012] The following steps are involved: Step 1: Replace the main cylinder (such as Figure 1 as shown) mounted on a fixture (as Figure 2 As shown in Figure 2), the main cylinder body rifling is divided into two sections, with a tool (such as Figure 3 The tool tip center is used as a programming reference, and radius compensation needs to be applied during machining (basic operation method of machining center); Step 2: Quickly move the tool to the zero position of the part coordinates, such as Figure 4 As shown; Step 3: Move the tool quickly along the negative direction of the Z axis to the second cup groove. Figure 5 As shown; Step 4: Linear interpolation is performed from the center of the second cup groove along the positive direction of the X axis. The tool tip cuts into the main hole wall. The X axis movement value is the radius value of the main hole, such as Figure 6 As shown; Step 5: The tool takes the end point of step 4 as the starting point and uses the part coordinates as the center for arc milling. Figure 7 As shown in the figure, because the tool feed direction is counterclockwise, counter-circular arc interpolation G03 is used. During the arc feed, the Z axis needs to be linearly fed in the negative direction to the second empty tool groove. The X-axis and Y-axis end point coordinates need to be calculated by function. Step 6: The tool is withdrawn linearly to the center of the main hole. Figure 8 As shown, the tool radius compensation is canceled at the same time, the first rifling is processed, and the second rifling is processed using the same method; Step 7. After processing is completed, the tool quickly moves outside the part along the positive direction of the Z axis and the program ends.

[0013] The method for installing the main cylinder body on the fixture in step 1 of the present invention is as follows: Relying on the flange surface and positioning holes of the main cylinder body, plus the outer circle of the part head, a two-pin positioning is formed on one side to ensure that the center position of the part is fixed. The height of the fixture covers all the processing requirements of the cylinder body. The bushing of the upper fixture cover can be replaced to meet the processing requirements of parts with different outer circles. The locking device at the bottom performs linear up and down movement to complete the clamping of the part. There is a threaded hole in the middle of the locking device, and the threaded hole can be installed with various lengths and types of tops. This set of fixtures is highly flexible and can meet the needs of different types of products. Secondly, this set of fixtures is small in size and does not take up space.

[0014] The processing tool in step 1 of the present invention is a carbide milling cutter with a diameter of 12 mm and a tool length of 170 mm. Because the processing material is cast aluminum 107, the tensile strength σb (MPa) ≥ 195, the elongation δ5 (%) ≥ 2, the hardness ≥ 70 (5 / 250 / 30) HB, the cutting performance is relatively good, the tool rake angle is 15°-20°, and the back angle is 15°-20°.

[0015] The calculation method in step 5 of the present invention is as follows: The first known condition is that the tool moves along the main hole wall in an arc, and the feed radius is the radius r of the main hole of the part (the main hole diameter is 22.2 mm); Known Condition 2: The Z-axis feed distance of the tool is the distance L from the second cup groove to an empty groove, which is 15 mm through actual measurement. Given the conditions, the helix angle α of the three-rifling is 20 degrees as marked on the drawing; When writing the program, first calculate the distance b that the tool travels when it feeds in the hole wall in an arc. Secondly, calculate the opposite side of a right triangle with an angle α of 20 degrees. The adjacent side is the Z-axis feed distance L=15mm, b=tanα×L=tan20×15=5.46mm, 5.46mm is the length of the arc that the tool travels when it feeds in an arc. The circumference of the main hole is C=69.708mm, the arc angle of the X-axis and Y-axis end points β=b / C×360=5.46 / 69.708×360=28.198 degrees, the coordinates of the X-axis end point are x=cosβ×r=cos28.198×11.1=9.783, and the coordinates of the Y-axis end point are y=sinβ×r= sin28.198×11.1=5.245, in this way, the end point coordinates of the X-axis and the Y-axis are obtained. When the diameter of the main hole changes, the radius compensation of the tool can be modified. When the main hole increases, the radius compensation decreases. When the main hole decreases, the tool radius can be increased.

[0016] In step five of the present invention, the processing parameters are a rotation speed of 5000 r / min, a feed speed of 100 mm / min, and a cutting depth of 0.3 mm.

Claims

1. A method for machining the rifling of a main cylinder, characterized in that: The following steps are involved: Step 1: Install the main cylinder body on the fixture. The rifling of the main cylinder body is divided into two sections. The center of the tool tip is used as the programming reference. Radius compensation needs to be applied during processing. Step 2: Quickly move the tool to the zero point of the part coordinates; Step 3: Move the tool quickly along the negative direction of the Z axis to the second cup groove; Step 4: Linear interpolation is performed from the center of the second cup groove along the positive direction of the X axis, and the tool tip cuts into the main hole wall. The X axis movement value is the radius value of the main hole; Step 5: The tool takes the end point of step 4 as the starting point and uses the part coordinates as the center for arc milling. Since the tool feed direction is counterclockwise, counter-circular arc interpolation is used. During the arc feed, the Z axis needs to feed linearly in the negative direction to the second empty tool slot. The X-axis and Y-axis end point coordinates need to be calculated by functions. Step 6: The tool is retracted linearly to the center of the main hole, and the tool radius compensation is canceled. The first rifling is processed and the second rifling is processed in the same way. Step 7. After processing is completed, the tool quickly moves outside the part along the positive direction of the Z axis and the program ends.

2. A method for machining the rifling of a main cylinder according to claim 1, characterized in that: The method for installing the main cylinder body on the fixture in step 1 is as follows: Relying on the flange surface and positioning hole of the main cylinder body, plus the outer circle of the part head, one side and two pins are formed to position the part, ensuring that the center position of the part is fixed. The height of the fixture covers all the processing requirements of the cylinder body. The upper fixture cover can replace the bushing to meet the processing needs of parts with different outer circles. The locking device at the bottom performs a linear up and down movement to complete the clamping of the part. There is a threaded hole in the middle of the locking device, and the threaded hole can be used to install tops of various lengths and types.

3. A method for machining the rifling of a main cylinder according to claim 1, characterized in that: The processing tool in step 1 is a carbide milling cutter, and the tool has a front angle of 15°-20° and a back angle of 15°-20°.

4. A method for machining the rifling of a main cylinder according to claim 1, characterized in that: The calculation method in step 5 is as follows: The first known condition is that the tool moves along the main hole wall in an arc and the feed radius is the radius r of the main hole of the part; Known Conditions: The feed distance of the Z axis of the second tool is the distance L from the second cup groove to an empty groove; Known conditions: The helix angle α of the three-rifling groove; When writing a program, first calculate the distance b that the tool travels when it is cutting in an arc on the hole wall. Secondly, calculate the opposite side of a right triangle with an angle of α. The adjacent side is the Z-axis cutting distance L, b=tanα×L, which is the length of the arc that the tool travels when it is cutting in an arc. The circumference of the main hole is C, the arc angles of the X-axis and Y-axis end points β=b / C×360, the coordinates of the X-axis end point are x=cosβ×r, and the coordinates of the Y-axis end point are y=sinβ×r. In this way, the coordinates of the X-axis and Y-axis end points are obtained. When the diameter of the main hole changes, the radius compensation of the tool can be modified. When the main hole increases, the radius compensation decreases. When the main hole decreases, the tool radius can be increased.

5. A method for machining the rifling of a main cylinder according to claim 1, characterized in that: In step 5, the processing parameters are a rotation speed of 5000 r / min, a feed speed of 100 mm / min, and a cutting depth of 0.3 mm.

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