Positioning fixture for grinding the raceway of a profiled nut

Abstract

The utility model relates to a positioning fixture, concretely relates to a positioning fixture for special-shaped nut raceway grinding. The fixture includes a fixture body, the bottom of fixture body is provided with arc tile, and the both sides inner wall of arc tile is respectively fixed with support strip; the top of fixture body is equipped with a limiting rod through hydraulic cylinder. The fixture can lift the nut through arc tile and support strip cooperation, make the central shaft of nut can be with the central shaft of rotating shaft on same straight line, and then can guarantee the accurate machining of ordinary lathe to nut raceway, guarantee machining precision, and reduce the comprehensive machining cost to nut, through the replacement of arc tile and support strip, can make the fixture adapt to different specifications nut, make the fixture can accurately position different specifications nut, can effectively improve the applicability of the fixture. Solve the nut and rotating shaft of existing ordinary lathe machining special-shaped nut different shaft, cannot process the problem of special-shaped nut.

Description

Technical Field

[0001] This utility model relates to a positioning fixture, specifically a positioning fixture for grinding the raceway of irregularly shaped nuts. Background Technology

[0002] An electric recirculating ball steering gear includes a screw, nut, steel balls, and an output shaft. The nut has raceways on its inner side, connecting it to the screw via these raceways and steel balls. The nut has toothed grooves on its outer side, which mesh with the teeth at the end of the output shaft. To ensure the motion accuracy of the screw and nut and guarantee precise steering, precise positioning is required during the grinding of the nut's raceways. Because of the toothed grooves on the outer side of the nut, one side has a thicker wall than the other, resulting in an irregular, non-standard circular shape. The common practice is to use a five-axis machining center, which does not require workpiece rotation, to machine the nut. After clamping and fixing the nut, a rotating tool is used to machine the helical raceways. However, five-axis machining centers are generally expensive, and the machining process requires programming, especially for machining the helical raceways on the inner wall of the nut, where programming is quite difficult. This leads to higher overall machining costs. Machining on a conventional lathe, on the other hand, uses a rotary axis to rotate the workpiece, thus machining it. This requires no programming (manual operation) or only simple programming, making programming easier; and conventional lathes are also cheaper. Although machining on a conventional lathe has a low overall processing cost, it requires fixing the nut to the rotating shaft using a fixture. If a conventional three-jaw chuck is used for clamping and positioning the nut, the nut's central axis will not be collinear with the machine tool's rotating shaft, leading to significant deviations during the grinding of the nut's raceway. Therefore, it is necessary to design a positioning fixture for grinding the raceways of irregularly shaped nuts to solve the above problems. Summary of the Invention

[0003] The purpose of this utility model is to provide a positioning fixture for grinding the raceways of irregular-shaped nuts, which can be precisely machined using a conventional lathe and reduces the overall machining cost.

[0004] The technical solution of this utility model is: A positioning fixture for grinding the raceways of irregularly shaped nuts comprises a fixture body, an arc-shaped plate, a support bar, a hydraulic cylinder, and a limiting rod. The fixture body is cylindrical, with an arc-shaped plate at the bottom of its inner wall. Multiple sets of mounting holes are provided on the inner walls of both sides of the arc-shaped plate, and support bars are axially fixed to these mounting holes using bolts. A hydraulic cylinder is mounted on the fixture body above the center of the arc-shaped plate, with the piston rod extending above the arc-shaped plate. A limiting rod is laterally mounted on the piston rod extending above the arc-shaped plate.

[0005] The bottom of the inner wall of the fixture body and the center of the outer wall of the arc-shaped tile are respectively provided with keyways, and the arc-shaped tile is connected to the fixture body through the keyways and keys.

[0006] A limiting block is fixedly installed in the middle of the front end face of the arc-shaped tile. The limiting block is in the shape of an inverted L, and the top end of the limiting block extends to the top of the arc-shaped tile between the support strips.

[0007] The fixture body has a counterweight installed at its bottom by fixing bolts.

[0008] The fixture body has a flange at its front end for connecting to the machine tool's rotating shaft.

[0009] The beneficial effects of this utility model are as follows: This positioning fixture for grinding the raceways of irregularly shaped nuts uses a circular arc plate and support bars to elevate the nut, ensuring that the nut's central axis is aligned with the central axis of the rotating shaft. This guarantees accurate machining of the nut's raceways using a conventional lathe, ensuring machining precision and reducing overall machining costs. By replacing the circular arc plate and support bars, the fixture can be adapted to different nut specifications, allowing for precise positioning of nuts of varying sizes and effectively improving its applicability. This solves the problem of existing conventional lathes being unable to machine irregularly shaped nuts due to the misalignment between the nut and the rotating shaft. Attached Figure Description

[0010] Figure 1 This is a front view schematic diagram of the present invention; Figure 2 This is a cross-sectional schematic diagram of the present invention; Figure 3 This is an isometric schematic diagram of the arc-shaped tile of this utility model.

[0011] In the figure: 1. Fixture body, 2. Arc-shaped tile, 3. Support bar, 4. Hydraulic cylinder, 5. Limiting rod, 6. Assembly hole, 7. Keyway, 8. Key, 9. Limiting block, 10. Counterweight block, 11. Flange, 12. Workpiece (nut), 13. Raceway, 14. Nut tooth groove. Detailed Implementation

[0012] This positioning fixture for grinding the raceways of irregularly shaped nuts consists of a fixture body 1, an arc-shaped bearing plate 2, support bars 3, a hydraulic cylinder 4, and a limiting rod 5. The fixture body 1 is cylindrical, and the bottom of its inner wall is fitted with the arc-shaped bearing plate 2. Multiple sets of mounting holes 6 are provided on the inner walls of both sides of the arc-shaped bearing plate 2, with each set of mounting holes 6 evenly distributed axially on the arc-shaped bearing plate 2. Support bars 3 are axially fixed to the mounting holes 6 using bolts. The hydraulic cylinder 4 is mounted on the fixture body 1 above the center of the arc-shaped bearing plate 2. The hydraulic cylinder 4 is connected to a slip ring via an oil pipe. The slip ring is slidably sealed to a lathe and fixedly connected to the lathe's rotating shaft. An oil supply groove is provided on the lathe at the front end of the slip ring, communicating with a hydraulic station to supply oil to the hydraulic cylinder 4 sequentially through the hydraulic station, the oil supply groove, the slip ring, and the oil pipe. The piston rod end of the hydraulic cylinder 4 extends above the arc-shaped plate 2, and a limit rod 5 is horizontally installed on the piston rod end of the hydraulic cylinder 4 extending above the arc-shaped plate 2. The function of the support bar 3 is to raise the nut by cooperating with the arc-shaped plate 2, so that the central axis of the nut is on the same straight line as the central axis of the fixture body, thereby ensuring the precise positioning of the nut, ensuring the machining accuracy of the nut raceway, and enabling the nut to be machined on a conventional lathe, reducing the overall cost of grinding the nut raceway. The function of the hydraulic cylinder 4 is to press the nut down by cooperating with the limit rod 5, thereby pressing the nut tightly onto the support bar 3 and fixing the nut; at the same time, the cooperation between the limit rod 5 and the nut tooth groove restricts the axial position of the nut to prevent the nut from sliding back and forth, and restricts the circumferential position of the nut to prevent the nut from rotating. The purpose of setting multiple sets of mounting holes 6 is to change the position of the support bar 3 by using the set of mounting holes 6, so that the position of the support bar 3 is adapted to the size of the nut, preventing the nut from being too small and getting stuck between the support bars 3; ensuring the support bar 3 supports the nut. Since the support bar 3 is connected to the arc-shaped tile plate 2 by fixing bolts, the support bar 3 can be replaced, so that the height of the support bar 3 can be adapted to the nut specifications, effectively enhancing the applicability and scope of application of the fixture.

[0013] The bottom of the inner wall of the fixture body 1 and the center of the outer wall of the arc tile plate 2 are respectively provided with keyways 7. The arc tile plate 2 is connected to the fixture body 1 through the keyways 7 and the key 8.

[0014] A limiting block 9 is fixedly installed at the center of the front end face of the arc-shaped tile 2. The limiting block 9 is inverted L-shaped, and its top end extends above the arc-shaped tile 3 between the support bars 3. The function of the limiting block 9 is to determine the position of the front end face of the nut during the clamping process, and thus determine the position of the nut tooth groove, so as to facilitate the insertion of the limiting rod 5 into the nut tooth groove, thereby facilitating the clamping of the nut; at the same time, after determining the position of the nut by the limiting block 9, the machining position of the nut raceway is determined to ensure machining accuracy.

[0015] A counterweight 10 is installed at the bottom of the fixture body 1 by fixing bolts. The counterweight 10 increases the weight of the fixture body 1 on the opposite side of the hydraulic cylinder 4. The weight of the counterweight 10 balances the weight of the hydraulic cylinder and the additional fixture body 1 assembly position where the hydraulic cylinder is installed, making the fixture body 1 less prone to vibration during rotation and further ensuring machining accuracy.

[0016] The front end of the fixture body 1 is provided with a flange 11 for connecting the rotating shaft of the machine tool.

[0017] When clamping the nut in this positioning fixture for grinding the raceways of irregularly shaped nuts, align the nut's tooth groove with the limiting rod 5, insert the nut between the support bars 3 until the front end face of the nut abuts against the limiting block 9. After the nut is inserted into place, activate the hydraulic cylinder 4, which drives the limiting rod 9 to insert into the nut's tooth groove. During the insertion process, the limiting rod 9 gradually presses the nut, squeezing and fixing it onto the support bar 3, thus securing the nut.

[0018] This positioning fixture for grinding the raceways of irregularly shaped nuts uses a circular arc plate and support bars to elevate the nut, ensuring that the nut's central axis is aligned with the central axis of the rotating shaft. This guarantees accurate machining of the nut's raceways using a conventional lathe, ensuring machining precision and reducing overall machining costs. By replacing the circular arc plate and support bars, the fixture can be adapted to different nut specifications, allowing for precise positioning of nuts of varying sizes and effectively improving its applicability. This solves the problem of existing conventional lathes being unable to machine irregularly shaped nuts due to the misalignment between the nut and the rotating shaft.

Claims

1. A positioning fixture for profile nut raceway grinding, which is composed of a fixture body (1), a circular arc tile (2), a support strip (3), a hydraulic cylinder (4) and a limiting rod (5), characterized in that: The fixture body (1) is cylindrical. The bottom of the inner wall of the fixture body (1) is provided with an arc plate (2). Multiple sets of assembly holes (6) are provided on the inner walls of both sides of the arc plate (2). Support bars (3) are fixedly installed on the assembly holes (6) along the axial direction by fixing bolts. A hydraulic cylinder (4) is provided on the fixture body (1) above the middle of the arc plate (2). The piston rod end of the hydraulic cylinder (4) extends to the top of the arc plate (2). A limit rod (5) is installed laterally on the piston rod end of the hydraulic cylinder (4) extending to the top of the arc plate (2).

2. The positioning fixture for profile nut raceway grinding according to claim 1, characterized in that: The bottom of the inner wall of the fixture body (1) and the center of the outer wall of the arc tile plate (2) are respectively provided with keyways (7), and the arc tile plate (2) is connected to the fixture body (1) through the keyways (7) and the key (8).

3. The positioning fixture for profile nut raceway grinding according to claim 1, characterized in that: A limiting block (9) is fixedly installed in the middle of the front end face of the arc tile (2). The limiting block (9) is in the shape of an inverted L and the top end of the limiting block (9) extends to the top of the arc tile (2) between the support strips (3).

4. The positioning fixture for profile nut raceway grinding according to claim 1, characterized in that: The bottom of the fixture body (1) is fitted with a counterweight (10) by fixing bolts.

5. The positioning fixture for profile nut raceway grinding according to claim 1, characterized in that: The fixture body (1) has a flange (11) at its front end for connecting the machine tool's rotating shaft.

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