A rack and pinion cylinder block machining method

Abstract

A machining method for a rack and pinion cylinder body includes a pre-processing step, a milling step, a boring step, a grinding and tapping step, and a workpiece inspection step. During the machining process, when boring the cylinder barrels, one cylinder barrel on the cylinder body is machined first, then the other cylinder barrel is machined. The relative horizontal and height dimensions between the reference alignment fixture and the cylinder body ensure that the two cylinder barrels remain coaxial during the turning process. This design not only allows the cylinder barrel center to be determined by the reference alignment fixture, enabling the two cylinder barrels to be machined independently, effectively reducing the tool overhang, but also eliminates the need for a special boring machine, effectively improving machining precision and efficiency, and reducing machining costs.

Description

Technical Field

[0001] This invention relates to a processing method, and more particularly to a processing method for a rack and pinion cylinder body, specifically applicable to a processing method for a rack and pinion cylinder body that operates synchronously with multiple rotary mechanisms without pressure fluctuations. Background Technology

[0002] A rack and pinion cylinder is a machine that uses a rack and pinion to convert the reciprocating motion of a hydraulic cylinder into the forward and reverse rotational motion of a gear shaft, and at the same time converts the thrust of the reciprocating cylinder into the output torque of the gear shaft.

[0003] The cylinder body of the rack and pinion cylinder is a crucial force-bearing and transmission component. During operation, the piston rod passes through the cylinder barrels on both sides of the rack and pinion cylinder into the gear cavity of the cylinder body. The piston rod then drives the gear meshing with the rack in the gear cavity to rotate, thereby generating torque. Therefore, ensuring a tight fit between the rack and the gear is essential. To achieve the required clearance, the spatial distance between the gear mounting centerline and the piston rod centerline must be strictly controlled. Furthermore, to ensure the smooth operation of the reciprocating cylinder, the coaxiality, cylindricity, and surface roughness of the cylinder barrels on both sides of the rack and pinion cylinder must also be ensured.

[0004] Currently, the cylinder body of a rack and pinion cylinder is typically machined on a boring machine using a specially designed tool holder or special cutting tool to form the cylinder barrels on both sides in one operation. While this method can ensure the coaxiality of the cylinder barrels at both ends of the rack and pinion cylinder to a certain extent, it still has the following drawbacks:

[0005] 1. Since both cylinders need to be machined in one operation, the overhang of the specially made tool holder or special tool must be greater than the total length of both cylinders. This causes the tool tip to be affected by radial force during cutting, which can easily lead to tool deflection and vibration. It is difficult to guarantee the machining quality, resulting in low coaxiality, cylindricity and roughness of the two cylinder sections.

[0006] 2. If the cylinder barrel is machined separately on both sides using a machine tool, it is difficult to accurately position the cylinder body to be machined, and misalignment often occurs between the two cylinder barrels.

[0007] 3. Due to the limitations of the machine tool's own precision, it is impossible to meet the requirements for the roughness of the cylinder inner wall. If a special high-precision machine tool is used, the cost will be high.

[0008] The information disclosed in this background section is intended only to enhance understanding of the overall background of this application and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art, which is that the large tool overhang leads to tool deflection and vibration, resulting in low coaxiality, cylindricity and roughness of the two cylinder sections, and to provide a machining method for the cylinder body of a rack and pinion cylinder.

[0010] To achieve the above objectives, the technical solution of the present invention is:

[0011] A method for machining a rack and pinion cylinder body, the method being used to machine the cylinder body to be machined, the cylinder body to be machined including a housing, a left cylinder barrel and a right cylinder barrel; a gear cavity is formed inside the housing, the left cylinder barrel and the right cylinder barrel are tubular structures, the left cylinder barrel and the right cylinder barrel are fixedly arranged on both sides of the housing respectively, the central axes of the left cylinder barrel and the right cylinder barrel coincide with each other, the central axes of the left cylinder barrel and the right cylinder barrel are located between the center of the gear cavity and the side of the gear cavity, and the inner cavities of the left cylinder barrel and the right cylinder barrel are both connected to the gear cavity;

[0012] The processing method includes the following steps:

[0013] Step 1: Pre-processing. Place the cast cylinder blank on the workbench. Determine the midpoint of the line connecting the two end faces of the gear cavity by measuring the midpoint of the line. Mark the midpoint reference line on the surface of the cylinder blank using a scribing ruler. Level the midpoint of the cylinder blank and use the midpoint as a reference to mark the machining allowance lines on each surface to be machined on the cylinder blank. At the same time, mark the four side generatrices of the left and right cylinder barrels on the left and right end faces of the cylinder blank using a scribing ruler. The cylinder blank to be machined is obtained. At this point, the first step of pre-processing is completed.

[0014] Step 2: Milling the workpiece. Place the cylinder body to be machined, after completing the pre-processing steps, on the rotary table of the milling machine, aligning the first machining surface of the cylinder body with the milling cutter. Adjust the cylinder body using the adjustable V-bolt support and correct its levelness, ensuring that the runout of the cylinder body's center surface during rotation is no more than 0.2mm. Then, fix the cylinder body on the rotary table. After fixing the cylinder body, the operator uses a milling cutter to mill the first machining surface of the gear cylinder according to the design drawing. After milling the first machining surface of the gear cylinder, the operator mills the D1 hole on the gear cylinder using the milling cutter. After milling the D1 hole, the operator chamfers the D1 hole. After chamfering the D1 hole, the operator uses the D1 hole as a reference to mill the gear cylinder. After milling the D3 hole, the operator chamfers the D3 hole. After the D3 hole is machined, the operator uses an edge finder to mark the center points of the left and right cylinders inside the cylinder. The line connecting the center points of the left and right cylinders is the central axis of the left and right cylinders. A correction band parallel to the central axis of the cylinder is milled on the cylinder body near the cylinder body using a milling cutter. After the correction band is machined, the cylinder body is flipped over and re-fixed on the milling machine. After the cylinder body is fixed, the operator mills the D2 hole on the gear cylinder using the D3 hole as a reference. After the D2 hole is milled, the operator chamfers the D2 hole and uses the D3 hole as a reference to machine a stepped surface and a sealing ring groove on the second machining surface of the cylinder body. At this time, the second step of milling the workpiece is completed.

[0015] Step 3: Boring the workpiece. Place the cylinder body to be machined, after completing the milling step in Step 2, on the worktable of a precision boring machine. Position one cylinder barrel directly opposite the boring tool. Adjust the worktable angle by using the boring machine to check the flatness runout of the cylinder body, ensuring the flatness of the first and second machined surfaces of the cylinder barrel is within 0.05. Confirm the cylinder barrel's central axis using the crosshairs. Determine the height of the cylinder barrel's center using the distance from the center to the correction zone and the dimension of the first machined surface. Then, determine the horizontal position of the cylinder barrel's center using the distance from the center to the side wall of the gear cavity. After determining the height and horizontal position of the cylinder's center, adjust the boring tool angle and position according to the height and horizontal position of the cylinder's center, and bore the corresponding cylinder of the cylinder body to be machined. After the cylinder is machined, the operator fixes the reference alignment fixture on the precision boring machine and measures the relative horizontal dimension X1 and relative height dimension X2 from the machined hole to the reference surface on the reference alignment fixture. After the measurement is completed, rotate the worktable of the precision boring machine 180°, find the cylinder's center through the relative horizontal dimension X1 and relative height dimension X2, and machine the remaining cylinder on the cylinder body to be machined. At this time, the third step of boring the workpiece is completed.

[0016] Step 4: Grinding and tapping the workpiece. Place the cylinder body 1 to be processed, which has completed the boring step in step 3, on the worktable. The operator grinds the inner walls of the left and right cylinder barrels using a grinding fixture until the roughness of the inner walls of the left and right cylinder barrels reaches Ra0.4. Tap each threaded hole on the cylinder body to be processed and fix a thread protection mesh at the opening of each threaded hole. After the thread protection mesh is set, chamfer the sharp angles of the cylinder body to be processed and deburr the workpiece. At this time, the fourth step of grinding and tapping the workpiece is completed.

[0017] Step 5: Inspect the workpiece. Place the cylinder body to be processed, which has completed the grinding and tapping steps in Step 4, on the worktable of the coordinate measuring machine. Use the coordinate measuring machine to inspect the three-dimensional position and dimensions of each processing position on the cylinder body. If the three-dimensional position and dimensions of each processing position on the cylinder body meet the processing requirements, the cylinder body is processed. If the three-dimensional position and dimensions of each processing position on the cylinder body do not meet the processing requirements, the cylinder body is scrapped. At this point, the rack and pinion cylinder body is processed.

[0018] The reference alignment fixture has a long strip structure and includes a reference surface and a support surface. The reference surface is the top surface of the reference alignment fixture, and the support surface is the bottom surface of the reference alignment fixture. When the reference alignment fixture is fixed on a precision boring machine, the support surface is in contact with the precision boring machine, and the reference surface is parallel to the spindle of the precision boring machine. The side wall of the reference alignment fixture is ground by a grinding machine, and the flatness of the side wall of the reference alignment fixture is less than 0.005.

[0019] The grinding fixture includes a grinding rod, a grinding sleeve, a handle, and a fixing nut. The grinding sleeve is a hollow tube structure, and its outer surface is the grinding surface. The diameter of the fixing nut is larger than that of the grinding sleeve. One end of the grinding rod is fixedly provided with a handle, and the other end of the grinding rod is provided with an external threaded rod. The other end of the grinding rod passes through the grinding sleeve and is fixedly connected to the fixing nut through the external threaded rod.

[0020] The grinding fixture also includes a shim, which is fitted onto the externally threaded rod. The grinding sleeve is made of cast iron and has a mesh size of 800 to 1200.

[0021] In the fourth step of grinding and tapping the workpiece, the operator uses grinding sleeves of different mesh sizes to grind the inner walls of the left and right cylinders in sequence, from low to high.

[0022] In the first step of the pre-processing step, the machining allowance of each surface to be machined on the cylinder body of the cylinder to be machined is 2mm on each side. Each surface to be machined includes the inner walls of the D1 hole, D2 hole, D3 hole, left cylinder 12 and right cylinder 13.

[0023] In the second step of milling the workpiece, the coaxiality between the step surface and the sealing ring groove and the D3 hole is 0.02.

[0024] In the third step of boring the workpiece, the distance from the center of the cylinder to the correction zone is set as L3. According to the design drawings, the design distance between the center of the cylinder and the center of the D1 hole is L1. At the same time, the distance between the center of the correction zone and the center of the D1 hole is measured as L2. The distance from the center of the cylinder to the correction zone is calculated by L3 = L2 - L1.

[0025] In the third step of boring the workpiece, the distance L2 between the center of the correction zone and the center of the D1 hole is obtained by measuring the distance between the edge of the D1 hole and the correction zone plus the radius R of the hole.

[0026] In the third step of boring the workpiece, a grinding allowance of 0.04 to 0.06 mm is left for the cylinder.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. In the machining method of a rack and pinion cylinder body according to the present invention, in the third step of boring the workpiece, the operator first machines one side of the cylinder barrel on the rack and pinion cylinder body using a boring machine. Then, by using a reference alignment fixture as a positioning reference, the relative horizontal dimension X1 and height dimension X2 between the machined cylinder barrel and the reference alignment fixture can be measured. After rotating the worktable of the precision boring machine 180°, the center of the unmachined cylinder barrel is found using the reference alignment fixture and the relative horizontal dimension X1 and height dimension X2. Then, the cylinder barrel is machined by the boring machine, so that the cylinder barrels on both sides of the rack and pinion cylinder body can be machined separately, requiring only a boring tool with a length greater than the total length of the cylinder barrel on one side. Therefore, this design can determine the cylinder barrel center through the reference alignment fixture, allowing the cylinder barrels on both sides to be machined separately, effectively reducing the overhang of the machining tool.

[0029] 2. In the machining method of a rack and pinion cylinder body of the present invention, in the second step of milling the workpiece, the center points of the left and right cylinder barrels are obtained by marking points inside the cylinder barrel using an edge finder, and a correction band parallel to the line connecting the center points of the left and right cylinder barrels is machined. In the third step of boring the workpiece, according to the design drawings, the design distance between the center of the cylinder barrel and the center of hole D1 is L1, and the distance between the correction band and the center of hole D1 is measured as L2. The operator can quickly calculate the distance from the center of the cylinder barrel to the correction band by L3 = L2 - L1, and accurately obtain the position of the central axis of the cylinder barrel by using the correction band as a reference and L3. Then, a high-precision cylinder barrel can be boring using a common precision boring machine. Therefore, this design can use the correction band as a reference to quickly calculate the position of the central axis of the cylinder barrel by using the drawings and measured dimensional parameters, and boring a high-precision cylinder barrel using a common precision boring machine, without the need for a special boring machine, effectively improving the machining precision and efficiency, and reducing machining costs.

[0030] 3. In the machining method of a rack and pinion cylinder body of the present invention, the grinding fixture includes a grinding rod, a grinding sleeve, and a handle. A handle is fixedly mounted on one side of the grinding rod, and the grinding sleeve is fitted onto the grinding rod. During operation, the grinding fixture can be controlled by the handle to grind the inner wall of the cylinder, improving the roughness of the inner wall and ensuring that the cylinder bore diameter meets design requirements. When grinding cylinders with different bore diameters, a grinding sleeve with a corresponding outer diameter can be replaced. Therefore, this design can effectively improve the roughness of the inner surface of the cylinder by grinding the inner wall of the cylinder using the grinding fixture. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the cylinder body to be processed in this invention.

[0032] Figure 2 yes Figure 1 A front view of the cylinder body of the hydraulic cylinder to be processed.

[0033] Figure 3 yes Figure 1 A sectional view of the cylinder body to be processed from a side angle.

[0034] Figure 4 yes Figure 1 A top-view sectional view of the cylinder body to be processed.

[0035] Figure 5 This is a diagram showing the positional relationship between the cylinder body of the hydraulic cylinder to be processed and the reference alignment fixture in this invention.

[0036] Figure 6 This is a process diagram of the second step of milling the workpiece in this invention.

[0037] Figure 7This is a process diagram of the third step of boring the workpiece in this invention.

[0038] Figure 8 This is a schematic diagram of the datum alignment fixture in this invention.

[0039] Figure 9 This is a schematic diagram of the grinding fixture in this invention.

[0040] Figure 10 This is a diagram showing the fit between the gear and the rack in this invention.

[0041] In the diagram: 1. Cylinder body to be machined; 11. Housing; 12. Left cylinder barrel; 13. Right cylinder barrel; 14. Alignment belt; 15. First machining surface; 16. Second machining surface; 17. Step surface; 18. Sealing ring groove; 2. Reference alignment fixture; 21. Reference surface; 22. Support surface; 3. Grinding fixture; 31. Grinding rod; 32. Grinding sleeve; 33. Handle; 34. Fixing nut; 35. External thread rod; 36. Washer. Detailed Implementation

[0042] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] See Figures 1 to 10 A method for machining a rack and pinion cylinder body is disclosed. The method is used to machine the cylinder body 1 to be machined. The cylinder body 1 to be machined includes a housing 11, a left cylinder barrel 12, and a right cylinder barrel 13. A gear cavity is formed inside the housing 11. The left cylinder barrel 12 and the right cylinder barrel 13 are tubular structures. The left cylinder barrel 12 and the right cylinder barrel 13 are fixedly arranged on both sides of the housing 11, respectively. The central axes of the left cylinder barrel 12 and the right cylinder barrel 13 coincide with each other. The central axes of the left cylinder barrel 12 and the right cylinder barrel 13 are located between the center of the gear cavity and the side of the gear cavity. The inner cavities of the left cylinder barrel 12 and the right cylinder barrel 13 are connected to the gear cavity.

[0044] The processing method includes the following steps:

[0045] Step 1: Pre-processing. Place the cast cylinder blank on the workbench. Determine the midpoint of the line connecting the two end faces of the gear cavity by measuring the midpoint of the line connecting the two end faces of the cylinder blank. Draw the midpoint reference line on the surface of the cylinder blank using a scribing ruler. Level the midpoint of the cylinder blank and use the midpoint of the cylinder blank as a reference to draw machining allowance lines on each surface to be machined on the cylinder blank. At the same time, draw four side generatrices of the left cylinder barrel 12 and the right cylinder barrel 13 on the left and right end faces of the cylinder blank using a scribing ruler to obtain the cylinder body 1 to be machined. At this time, the first step of pre-processing is completed.

[0046] Step 2: Milling the workpiece. Place the cylinder body 1, which has undergone pre-processing, on the rotary table of the milling machine, aligning the first machining surface 15 of the cylinder body 1 with the milling cutter. Adjust the cylinder body 1 using the adjustable V-bolt support and correct its levelness, ensuring that the runout of the center plane of the cylinder body 1 during rotation is no more than 0.2mm. Then, fix the cylinder body 1 on the rotary table. After fixing the cylinder body 1, the operator uses a milling cutter to mill the first machining surface 15 of the gear cylinder of the cylinder body 1 according to the design in the drawing. After milling the first machining surface 15 of the gear cylinder, the operator mills the D1 hole on the gear cylinder using the milling cutter. After milling the D1 hole, the operator chamfers the D1 hole. After chamfering the D1 hole, the operator uses the D1 hole as a reference to mill the D3 hole on the gear cylinder using the milling cutter. After the D3 hole is milled, the operator chamfers the D3 hole. After the D3 hole is machined, the operator uses an edge finder to mark the center points of the left cylinder 12 and the right cylinder 13 inside the cylinder. The line connecting the center points of the left cylinder 12 and the right cylinder 13 is the central axis of the left cylinder 12 and the right cylinder 13. A correction band 14 parallel to the central axis of the cylinder is milled on the cylinder body 1 near the cylinder using a milling cutter. After the correction band 14 is machined, the cylinder body 1 is flipped over and refixed on the milling machine. After the cylinder body 1 is fixed, the operator mills the D2 hole on the gear cylinder with the D3 hole as the reference. After the D2 hole is milled, the operator chamfers the D2 hole and uses the D3 hole as the reference to machine the step surface 17 and the sealing ring groove 18 on the second machining surface 16 of the cylinder body 1. At this time, the second step of milling the workpiece is completed.

[0047] Step 3: Boring the workpiece. Place the cylinder body 1 to be machined, which has completed the milling step in Step 2, on the worktable of the precision boring machine. Position one of the cylinder barrels of the cylinder body 1 directly opposite the boring tool. Adjust the worktable angle by using the boring machine to adjust the flatness runout of the cylinder body 1, ensuring the flatness of the first machined surface 15 and the second machined surface 16 of the cylinder barrel is within 0.05. Confirm the central axis of the cylinder barrel using the crosshairs. Determine the height of the cylinder barrel's center using the distance from the center of the cylinder barrel to the correction zone and the dimension of the first machined surface 15. Finally, determine the horizontal position of the cylinder barrel's center using the distance from the center of the cylinder barrel to the side wall of the gear cavity. After determining the height and horizontal position of the cylinder center, adjust the boring tool angle and position according to the height and horizontal position of the cylinder center, and bore the corresponding cylinder of the cylinder body 1 to be machined. After the cylinder is machined, the operator fixes the reference alignment fixture 2 on the precision boring machine and measures the relative horizontal dimension X1 and relative height dimension X2 from the machined hole to the reference surface 21 on the reference alignment fixture 2. After the measurement is completed, rotate the worktable of the precision boring machine 180°, find the cylinder center through the relative horizontal dimension X1 and relative height dimension X2, and machine the remaining cylinder on the cylinder body 1 to be machined. At this time, the third step of boring the workpiece is completed.

[0048] Step 4: Grinding and tapping the workpiece. Place the cylinder body 1 to be processed, which has completed the boring step in step 3, on the worktable. The operator grinds the inner walls of the left cylinder 12 and the right cylinder 13 using the grinding fixture 3 until the roughness of the inner walls of the left cylinder 12 and the right cylinder 13 reaches Ra0.4. Tap each threaded hole on the cylinder body 1 to be processed, and fix a thread protection mesh at the opening of each threaded hole. After the thread protection mesh is set, chamfer the sharp angles of the cylinder body 1 to be processed and deburr the workpiece. At this time, the fourth step of grinding and tapping the workpiece is completed.

[0049] Step 5: Inspect the workpiece. Place the cylinder body 1 to be processed, which has completed the grinding and tapping steps in Step 4, on the worktable of the coordinate measuring machine. Use the coordinate measuring machine to inspect the three-dimensional position and dimensions of each processing position on the cylinder body 1. If the three-dimensional position and dimensions of each processing position on the cylinder body 1 meet the processing requirements, the cylinder body 1 is processed. If the three-dimensional position and dimensions of each processing position on the cylinder body 1 do not meet the processing requirements, the cylinder body 1 is scrapped. At this point, the rack and pinion cylinder body is processed.

[0050] The reference alignment fixture 2 has a long strip structure. The reference alignment fixture 2 includes a reference surface 21 and a support surface 22. The reference surface 21 is the top surface of the reference alignment fixture 2, and the support surface 22 is the bottom surface of the reference alignment fixture 2. When the reference alignment fixture 2 is fixed on a precision boring machine, the support surface 22 is in contact with the precision boring machine, and the reference surface 21 is parallel to the spindle of the precision boring machine. The side wall of the reference alignment fixture 2 is ground by a grinding machine, and the flatness of the side wall of the reference alignment fixture 2 is less than 0.005.

[0051] The grinding fixture 3 includes a grinding rod 31, a grinding sleeve 32, a handle 33, and a fixing nut 34. The grinding sleeve 32 is a hollow tube structure, and its outer surface is a grinding surface. The diameter of the fixing nut 34 is larger than the diameter of the grinding sleeve 32. One end of the grinding rod 31 is fixedly provided with a handle 33, and the other end of the grinding rod 31 is provided with an external thread rod 35. The other end of the grinding rod 31 passes through the grinding sleeve 32 and is fixedly connected to the fixing nut 34 through the external thread rod 35 thereon.

[0052] The grinding fixture 3 also includes a shim 36, which is sleeved on the external threaded rod 35. The grinding sleeve 32 is a cast iron part, and the mesh size of the grinding sleeve 32 is 800 to 1200 mesh.

[0053] In the fourth step of grinding and tapping the workpiece, the operator uses grinding sleeves 32 with different mesh sizes from low to high to grind the inner walls of the left cylinder 12 and the right cylinder 13.

[0054] In the first step of the pre-processing step, the machining allowance of each surface to be machined on the cylinder body 1 of the oil cylinder to be machined is 2mm on each side. Each surface to be machined includes the inner walls of the D1 hole, D2 hole, D3 hole, left cylinder 12 and right cylinder 13.

[0055] In the second step of milling the workpiece, the coaxiality between the step surface and the sealing ring groove and the D3 hole is 0.02.

[0056] In the third step of boring the workpiece, the distance from the center of the cylinder to the correction zone is set as L3. According to the design drawings, the design distance between the center of the cylinder and the center of the D1 hole is L1. At the same time, the distance between the center of the correction zone and the center of the D1 hole is measured as L2. The distance from the center of the cylinder to the correction zone is calculated by L3 = L2 - L1.

[0057] In the third step of boring the workpiece, the distance L2 between the center of the correction zone and the center of the D1 hole is obtained by measuring the distance between the edge of the D1 hole and the correction zone plus the radius R of the hole.

[0058] In the third step of boring the workpiece, a grinding allowance of 0.04 to 0.06 mm is left for the cylinder.

[0059] The principle of this invention is explained as follows:

[0060] During operation, the gear and rack of the rack cylinder require a high degree of fit. Therefore, the spatial distance between the center line of the gear cavity and the center lines of the shaft holes of the left cylinder 12 and the right cylinder 13 must be strictly controlled to ensure the fit clearance between them. The center line of the gear cavity and the center lines of the shaft holes of the left cylinder 12 and the right cylinder 13 are mutually perpendicular skew lines in space. While ensuring that they are mutually perpendicular, the shortest distance between them must also be ensured. At the same time, in order to ensure smooth reciprocating motion of the rack, the center lines of the shaft holes of the left cylinder 12 and the right cylinder 13 need to ensure a high degree of coaxiality.

[0061] The center lines of the left cylinder 12 and the right cylinder 13 are the lines connecting the four side generatrices of each cylinder at the end face, found by using a scribing ruler. The scribing of the center lines is done before machining on the machine tool. The four side generatrices of the cylinder casting surface obtained by this method serve as a rough reference, mainly used to check the allowance of the blank. Example

[0062] A method for machining a rack and pinion cylinder body is disclosed. The method is used to machine the cylinder body 1 to be machined. The cylinder body 1 to be machined includes a housing 11, a left cylinder barrel 12, and a right cylinder barrel 13. A gear cavity is formed inside the housing 11. The left cylinder barrel 12 and the right cylinder barrel 13 are tubular structures. The left cylinder barrel 12 and the right cylinder barrel 13 are fixedly arranged on both sides of the housing 11, respectively. The central axes of the left cylinder barrel 12 and the right cylinder barrel 13 coincide with each other. The central axes of the left cylinder barrel 12 and the right cylinder barrel 13 are located between the center of the gear cavity and the side of the gear cavity. The inner cavities of the left cylinder barrel 12 and the right cylinder barrel 13 are connected to the gear cavity.

[0063] The processing method includes the following steps:

[0064] Step 1: Pre-processing. Place the cast cylinder blank on the workbench. Determine the midpoint of the line connecting the two end faces of the gear cavity by measuring the midpoint of the line connecting the two end faces of the cylinder blank. Draw the midpoint reference line on the surface of the cylinder blank using a scribing ruler. Level the midpoint of the cylinder blank and use the midpoint of the cylinder blank as a reference to draw machining allowance lines on each surface to be machined on the cylinder blank. At the same time, draw four side generatrices of the left cylinder barrel 12 and the right cylinder barrel 13 on the left and right end faces of the cylinder blank using a scribing ruler to obtain the cylinder body 1 to be machined. At this time, the first step of pre-processing is completed.

[0065] Step 2: Milling the workpiece. Place the cylinder body 1, which has undergone pre-processing, on the rotary table of the milling machine, aligning the first machining surface 15 of the cylinder body 1 with the milling cutter. Adjust the cylinder body 1 using the adjustable V-bolt support and correct its levelness, ensuring that the runout of the center plane of the cylinder body 1 during rotation is no more than 0.2mm. Then, fix the cylinder body 1 on the rotary table. After fixing the cylinder body 1, the operator uses a milling cutter to mill the first machining surface 15 of the gear cylinder of the cylinder body 1 according to the design in the drawing. After milling the first machining surface 15 of the gear cylinder, the operator mills the D1 hole on the gear cylinder using the milling cutter. After milling the D1 hole, the operator chamfers the D1 hole. After chamfering the D1 hole, the operator uses the D1 hole as a reference to mill the D3 hole on the gear cylinder using the milling cutter. After the D3 hole is milled, the operator chamfers the D3 hole. After the D3 hole is machined, the operator uses an edge finder to mark the center points of the left cylinder 12 and the right cylinder 13 inside the cylinder. The line connecting the center points of the left cylinder 12 and the right cylinder 13 is the central axis of the left cylinder 12 and the right cylinder 13. A correction band 14 parallel to the central axis of the cylinder is milled on the cylinder body 1 near the cylinder using a milling cutter. After the correction band 14 is machined, the cylinder body 1 is flipped over and refixed on the milling machine. After the cylinder body 1 is fixed, the operator mills the D2 hole on the gear cylinder with the D3 hole as the reference. After the D2 hole is milled, the operator chamfers the D2 hole and uses the D3 hole as the reference to machine the step surface 17 and the sealing ring groove 18 on the second machining surface 16 of the cylinder body 1. At this time, the second step of milling the workpiece is completed.

[0066] Step 3: Boring the workpiece. Place the cylinder body 1 to be machined, which has completed the milling step in Step 2, on the worktable of the precision boring machine. Position one of the cylinder barrels of the cylinder body 1 directly opposite the boring tool. Adjust the worktable angle by using the boring machine to adjust the flatness runout of the cylinder body 1, ensuring the flatness of the first machined surface 15 and the second machined surface 16 of the cylinder barrel is within 0.05. Confirm the central axis of the cylinder barrel using the crosshairs. Determine the height of the cylinder barrel's center using the distance from the center of the cylinder barrel to the correction zone and the dimension of the first machined surface 15. Finally, determine the horizontal position of the cylinder barrel's center using the distance from the center of the cylinder barrel to the side wall of the gear cavity. After determining the height and horizontal position of the cylinder center, adjust the boring tool angle and position according to the height and horizontal position of the cylinder center, and bore the corresponding cylinder of the cylinder body 1 to be machined. After the cylinder is machined, the operator fixes the reference alignment fixture 2 on the precision boring machine and measures the relative horizontal dimension X1 and relative height dimension X2 from the machined hole to the reference surface 21 on the reference alignment fixture 2. After the measurement is completed, rotate the worktable of the precision boring machine 180°, find the cylinder center through the relative horizontal dimension X1 and relative height dimension X2, and machine the remaining cylinder on the cylinder body 1 to be machined. At this time, the third step of boring the workpiece is completed.

[0067] Step 4: Grinding and tapping the workpiece. Place the cylinder body 1 to be processed, which has completed the boring step in step 3, on the worktable. The operator grinds the inner walls of the left cylinder 12 and the right cylinder 13 using the grinding fixture 3 until the roughness of the inner walls of the left cylinder 12 and the right cylinder 13 reaches Ra0.4. Tap each threaded hole on the cylinder body 1 to be processed, and fix a thread protection mesh at the opening of each threaded hole. After the thread protection mesh is set, chamfer the sharp angles of the cylinder body 1 to be processed and deburr the workpiece. At this time, the fourth step of grinding and tapping the workpiece is completed.

[0068] Step 5: Inspect the workpiece. Place the cylinder body 1 to be processed, which has completed the grinding and tapping steps in Step 4, on the worktable of the coordinate measuring machine. Use the coordinate measuring machine to inspect the three-dimensional position and dimensions of each processing position on the cylinder body 1. If the three-dimensional position and dimensions of each processing position on the cylinder body 1 meet the processing requirements, the cylinder body 1 is processed. If the three-dimensional position and dimensions of each processing position on the cylinder body 1 do not meet the processing requirements, the cylinder body 1 is scrapped. At this time, the rack and pinion cylinder body is processed. The reference alignment fixture 2 is a long strip structure. The reference alignment fixture 2 includes a reference surface 21 and a support surface 22. The reference surface 21 is the top surface of the reference alignment fixture 2, and the support surface 22 is the bottom surface of the reference alignment fixture 2. When the reference alignment fixture 2 is fixed on the precision boring machine, the support surface 21... 2. The reference surface 21 is in contact with a precision boring machine and parallel to the spindle of the precision boring machine. The sidewall of the reference alignment fixture 2 is ground by a grinding machine, and the flatness of the sidewall of the reference alignment fixture 2 is less than 0.005. The grinding fixture 3 includes a grinding rod 31, a grinding sleeve 32, a handle 33, and a fixing nut 34. The grinding sleeve 32 is a hollow tube structure, and the outer surface of the grinding sleeve 32 is the grinding surface. The diameter of the fixing nut 34 is larger than the diameter of the grinding sleeve 32. One end of the grinding rod 31 is fixedly provided with a handle 33, and the other end of the grinding rod 31 is provided with an external thread rod 35. The other end of the grinding rod 31 passes through the grinding sleeve 32 and is fixedly connected to the fixing nut 34 through the external thread rod 35. The grinding fixture 3 also includes a washer 36, which is sleeved on the external thread rod 35. The grinding sleeve 32 is a cast iron part. The grinding sleeve 32 has a mesh size of 800 to 1200. In the fourth step of grinding and tapping the workpiece, the operator uses grinding sleeves 32 with different mesh sizes from low to high to grind the inner walls of the left cylinder 12 and the right cylinder 13. In the first step of pre-processing, the machining allowance for each surface to be machined on the cylinder body 1 is 2mm on one side. Each surface to be machined includes the D1 hole, D2 hole, D3 hole, and the inner walls of the left cylinder 12 and the right cylinder 13. In the second step of milling the workpiece, the coaxiality between the step surface and the sealing ring groove and the D3 hole is 0.02. In the third step of boring the workpiece, a grinding allowance of 0.04 to 0.06mm is left for the cylinder. Example

[0069] Example 2 is basically the same as Example 1, except that:

[0070] In the third step of boring the workpiece, the distance from the center of the cylinder to the correction zone is set as L3. According to the design drawings, the design distance between the center of the cylinder and the center of the D1 hole is L1. At the same time, the distance between the center of the correction zone and the center of the D1 hole is measured as L2. The distance from the center of the cylinder to the correction zone is calculated by L3 = L2 - L1. Example

[0071] Example 3 is basically the same as Example 2, except that:

[0072] In the third step of boring the workpiece, the distance L2 between the center of the correction zone and the center of the D1 hole is obtained by measuring the distance between the edge of the D1 hole and the correction zone plus the radius R of the hole.

[0073] The above description is only a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Any equivalent modifications or changes made by those skilled in the art based on the content disclosed in the present invention should be included within the scope of protection set forth in the claims.

Claims

1. A method for machining the cylinder body of a rack and pinion cylinder, characterized in that: The processing method is used to process the cylinder body (1) of the hydraulic cylinder to be processed. The cylinder body (1) includes a shell (11), a left cylinder (12) and a right cylinder (13). A gear cavity is provided inside the shell (11). The left cylinder (12) and the right cylinder (13) are tubular structures. The left cylinder (12) and the right cylinder (13) are fixedly arranged on both sides of the shell (11). The central axes of the left cylinder (12) and the right cylinder (13) coincide with each other. The central axes of the left cylinder (12) and the right cylinder (13) are located between the center of the gear cavity and the side of the gear cavity. The inner cavities of the left cylinder (12) and the right cylinder (13) are connected to the gear cavity. The processing method includes the following steps: Step 1: Pre-processing. Place the cast cylinder blank on the workbench. Determine the midpoint of the line connecting the two end faces of the gear cavity by measuring the midpoint of the line connecting the two end faces of the cylinder blank. Draw the midpoint reference line on the surface of the cylinder blank using a scribing ruler. Level the midpoint of the cylinder blank. Use the midpoint of the cylinder blank as a reference to draw machining allowance lines on each surface to be machined on the cylinder blank. At the same time, draw the four side generatrices of the left cylinder (12) and right cylinder (13) on the left and right end faces of the cylinder blank using a scribing ruler to obtain the cylinder body (1) to be machined. At this time, the first step of pre-processing is completed. Step 2: Milling the workpiece. Place the cylinder body (1) to be machined, which has completed the pre-processing steps, on the rotary table of the milling machine. Align the first machining surface (15) of the cylinder body (1) with the milling cutter of the milling machine. Adjust the cylinder body (1) and correct its levelness by using the adjustable V-bolt support. Ensure that the runout of the center plane of the cylinder body (1) during rotation is no more than 0.2 mm. Then fix the cylinder body (1) on the rotary table. On the workbench, after the cylinder body (1) to be processed is fixed, the operator uses a milling cutter to mill the first machining surface (15) of the gear cylinder of the cylinder body (1) according to the design of the drawing. After the first machining surface (15) of the gear cylinder is milled, the operator mills the D1 hole on the gear cylinder with a milling cutter. After the D1 hole is milled, the operator chamfers the D1 hole. After the D1 hole is chamfered, the operator uses the D1 hole as a reference to mill the D3 hole on the gear cylinder with a milling cutter. After milling, the operator chamfers the D3 hole. After the D3 hole is machined, the operator uses an edge finder to mark the center points of the left cylinder (12) and right cylinder (13) inside the cylinder. The line connecting the center points of the left cylinder (12) and right cylinder (13) is the central axis of the left cylinder (12) and right cylinder (13). A correction band (14) parallel to the central axis of the cylinder is milled on the cylinder body (1) near the cylinder using a milling cutter. When the correction band (14) is... After processing, the cylinder body (1) to be processed is flipped over and fixed on the milling machine. After the cylinder body (1) to be processed is fixed, the operator mills the D2 hole on the gear cylinder with the D3 hole as the reference and the milling cutter. After the D2 hole is milled, the operator chamfers the D2 hole and uses the D3 hole as the reference to mill the step surface (17) and sealing ring groove (18) on the second processing surface (16) of the cylinder body (1) to be processed with the milling cutter. At this time, the second step of milling the workpiece is completed. Step 3: Boring the workpiece. Place the cylinder body (1) to be machined, which has completed the milling step in step 2, on the worktable of the precision boring machine. Make one of the cylinder barrels of the cylinder body (1) face the boring tool of the boring machine. Adjust the flatness runout of the cylinder body (1) to be machined by the boring machine and adjust the angle of the boring machine worktable so that the flatness of the first machined surface (15) and the second machined surface (16) of the cylinder barrel is within 0.

05. Confirm the center axis of the cylinder barrel through the crosshairs of the cylinder barrel. Determine the height position of the cylinder barrel center by the distance from the cylinder barrel center to the correction zone and the dimension of the first machined surface (15). Then, obtain the horizontal position of the cylinder barrel center by the distance from the cylinder barrel center to the side wall of the gear cavity. After determining the height and horizontal position of the cylinder center, adjust the boring tool angle and position according to the height and horizontal position of the cylinder center, and bore the corresponding cylinder of the cylinder body (1) to be machined. After the cylinder is machined, the operator fixes the reference alignment fixture (2) on the precision boring machine and measures the relative horizontal dimension X1 and relative height dimension X2 of the machined hole to the reference surface (21) on the reference alignment fixture (2). After the measurement is completed, rotate the worktable of the precision boring machine 180°, find the cylinder center through the relative horizontal dimension X1 and relative height dimension X2, and machine the remaining cylinder on the cylinder body (1) to be machined. At this time, the third step of boring the workpiece is completed. Step 4: Grinding and tapping the workpiece. Place the cylinder body (1) to be processed, which has completed the boring step in step 3, on the worktable. The operator grinds the inner walls of the left cylinder (12) and the right cylinder (13) using the grinding fixture (3) until the roughness of the inner walls of the left cylinder (12) and the right cylinder (13) reaches Ra0.

4. Tap each thread hole on the cylinder body (1) to be processed and fix the thread protection mesh at the opening of each thread hole. After the thread protection mesh is set, the sharp angle of the cylinder body (1) to be processed is blunted and the workpiece is deburred. At this time, the fourth step of grinding and tapping the workpiece is completed. Step 5: Inspect the workpiece. Place the cylinder body (1) to be processed, which has completed the grinding and tapping steps in Step 4, on the worktable of the coordinate measuring machine. Use the coordinate measuring machine to inspect the three-dimensional position and size of each processing position on the cylinder body (1). If the three-dimensional position and size of each processing position on the cylinder body (1) meet the processing requirements, the cylinder body (1) to be processed is completed. If the three-dimensional position and size of each processing position on the cylinder body (1) do not meet the processing requirements, the cylinder body (1) to be processed is scrapped. At this time, the rack cylinder body is completed. The reference alignment fixture (2) is a long strip structure. The reference alignment fixture (2) includes a reference surface (21) and a support surface (22). The reference surface (21) is the top surface of the reference alignment fixture (2), and the support surface (22) is the bottom surface of the reference alignment fixture (2). When the reference alignment fixture (2) is fixed on a precision boring machine, the support surface (22) is in contact with the precision boring machine, and the reference surface (21) is parallel to the spindle of the precision boring machine. The side wall of the reference alignment fixture (2) is ground by a grinding machine, and the flatness of the side wall of the reference alignment fixture (2) is less than 0.

005. The grinding fixture (3) includes a grinding rod (31), a grinding sleeve (32), a handle (33), and a fixing nut (34). The grinding sleeve (32) is a hollow tube structure, and the outer surface of the grinding sleeve (32) is a grinding surface. The diameter of the fixing nut (34) is larger than the diameter of the grinding sleeve (32). One end of the grinding rod (31) is fixedly provided with a handle (33), and the other end of the grinding rod (31) is provided with an external thread rod (35). The other end of the grinding rod (31) passes through the grinding sleeve (32) and is fixedly connected to the fixing nut (34) through the external thread rod (35).

2. The machining method for a rack and pinion cylinder body according to claim 1, characterized in that: The grinding fixture (3) also includes a shim (36), which is fitted onto the external thread rod (35). The grinding sleeve (32) is made of cast iron and has a mesh size of 800 to 1200.

3. The machining method for a rack and pinion cylinder body according to claim 2, characterized in that: In the fourth step of grinding and tapping the workpiece, the operator uses grinding sleeves (32) of different mesh sizes to grind the inner walls of the left cylinder (12) and the right cylinder (13) in sequence from low to high.

4. The machining method for a rack and pinion cylinder body according to claim 3, characterized in that: In the first step of the pre-processing step, the machining allowance of each surface to be machined on the cylinder body (1) to be machined is 2mm on each side. Each surface to be machined includes the inner walls of the D1 hole, D2 hole, D3 hole, left cylinder (12) and right cylinder (13).

5. A method for machining a rack and pinion cylinder body according to claim 4, characterized in that: In the second step of milling the workpiece, the coaxiality between the step surface and the sealing ring groove and the D3 hole is 0.

02.

6. A method for machining a rack and pinion cylinder body according to any one of claims 1 to 5, characterized in that: In the third step of boring the workpiece, the distance from the center of the cylinder to the correction zone is set as L3. According to the design drawings, the design distance between the center of the cylinder and the center of the D1 hole is L1. At the same time, the distance between the center of the correction zone and the center of the D1 hole is measured as L2. The distance from the center of the cylinder to the correction zone is calculated by L3 = L2 - L1.

7. A method for machining a rack and pinion cylinder body according to claim 6, characterized in that: In the third step of boring the workpiece, the distance L2 between the center of the correction zone and the center of the D1 hole is obtained by measuring the distance between the edge of the D1 hole and the correction zone plus the radius R of the hole.

8. A method for machining a rack and pinion cylinder body according to claim 7, characterized in that: In the third step of boring the workpiece, a grinding allowance of 0.04 to 0.06 mm is left for the cylinder.

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