Numerical control lathe soft claw turning clamp and soft claw self-centering method

Abstract

The invention discloses a numerical control lathe soft claw turning clamp and a soft claw self-centering method, and relates to the field of numerical control lathe soft claw turning. The clamp body is provided with three track grooves, and the three track grooves are distributed at intervals at the same angle of 120 degrees by taking the central axis of the clamp body as the circle center; according to the clamp, the cutter relieving phenomenon caused by the fact that a fit clearance exists between the soft claw and a chuck base in a traditional method is eliminated, before turning, the soft claw is forcibly locked under the action of strong rotating inertia force, the clearance is eliminated, a high-rigidity state is formed, it is guaranteed that the contour of the turned soft claw is real and accurate, and the machining precision is improved. A reliable precision reference is provided for subsequent workpiece machining; by using the clamp, dependence on high-precision cylindrical bars is abandoned, the clamp forms a centering reference, a factory does not need to prepare and manage a series of bars with different diameters, the material and storage cost is remarkably reduced, and the operation process is simplified.

Description

Technical Field

[0001] This invention relates to the field of CNC lathe soft jaw turning technology, specifically to a CNC lathe soft jaw turning fixture and a soft jaw self-centering method. Background Technology

[0002] In CNC turning, to ensure the form and position tolerances of shafts and sleeves, pre-machined outer diameters or inner holes are commonly used as positioning datums for subsequent processes. This requires high-precision clamping using soft jaws on a CNC lathe. After being mounted to the chuck, the soft jaws themselves must also undergo final turning on the machine tool to ensure the accuracy of their positioning surfaces. Currently, the conventional method for turning soft jaws in the industry is to use a cylindrical bar of known precise dimensions as a process datum, clamping it in the center of the soft jaws, using clamping force to force the soft jaws into initial positioning, and then turning it.

[0003] On the one hand, the soft jaws are installed by meshing with the chuck base through the serrated structure at their bottom. There is an unavoidable multi-tooth meshing clearance between the two. When subjected to cutting forces during turning, the soft jaws are prone to "tool deflection" (that is, the cutting force of the tool on the soft jaws will push them to make a slight displacement within the meshing clearance, causing the turning contour to deviate from the expected shape). This results in a distortion of the final formed contour of the soft jaws, which directly affects the machining accuracy of subsequent workpieces. On the other hand, relying on cylindrical bar stock for centering requires the factory to prepare a complete set of high-precision bars of different diameters to meet the machining needs of different parts. This not only increases material and storage costs, but also makes the operation process cumbersome and time-consuming, resulting in poor overall machining efficiency and economy. Summary of the Invention

[0004] In order to overcome the above-mentioned technical problems, the purpose of this invention is to provide a CNC lathe soft jaw turning fixture and a soft jaw self-centering method.

[0005] The objective of this invention can be achieved through the following technical solutions: A CNC lathe soft jaw turning fixture for driving a soft jaw mounted on a chuck to perform a centripetal motion, comprising: The assembly slot is located on the side of the soft jaw facing away from the chuck; The clamping body has three track grooves, which are distributed at 120° intervals around the central axis of the clamping body. The movable component is detachably installed in the assembly slot. There are three movable components. The movable components are movably connected in the track slot. The movable components pass through the track slot to axially limit the clamping body on the movable body. When the chuck rotates, the track groove is configured to drive the three moving parts to generate centripetal displacement along the track groove through its constraint, thereby achieving automatic clamping and centering of the soft jaw.

[0006] As a further aspect of the present invention: the contour curve equation of the trajectory groove is defined by a self-centering trajectory equation, which is: Where ρ is the instantaneous radius of curvature of the moving part, R is the initial radius of the moving part, and υ is the linear velocity of the moving part. Let ω be the angle through which the chuck rotates, and ω be the angular velocity of the chuck.

[0007] As a further aspect of the present invention: a through hole is provided in the middle of the clamping body for soft claw cutting.

[0008] As a further aspect of the present invention: the movable component includes a movable pin detachably installed in the assembly groove, and a limiting screw detachably installed on the side of the movable pin away from the chuck, the limiting screw being used to axially limit the clamp body. The assembly groove is a countersunk hole for screws on a soft claw. The movable pin is threaded into the assembly groove, and the limiting screw is threaded into the movable pin.

[0009] As a further aspect of the present invention, the radius of the through hole is set to be the minimum value under the premise of satisfying the condition of no interference between the turning tool and the cutting tool.

[0010] A self-centering method for soft jaws, using a CNC lathe soft jaw turning fixture as described in any of the preceding descriptions, includes the following steps: S1: Adjust the radial position of the soft jaws on the jaw base according to the diameter of the part to be processed; S2: Install the clamping body onto the soft jaws, and manually rotate the clamping body so that the three movable parts are respectively aligned with the assembly slots on the three soft jaws; S3: Pass the movable part through the track groove on the clamp body and then insert and fix it in the assembly groove of the soft claw; S4: Start the lathe spindle and use the tangential inertial force of the chuck to drive the moving parts to move in the centripetal direction along the track groove and automatically clamp the soft jaws. S5: Perform turning machining on the soft jaws. After machining is completed, stop the spindle and remove the fixture.

[0011] As a further aspect of the present invention: the movement of the movable component in the trajectory groove is based on a self-centering motion trajectory equation. control.

[0012] As a further aspect of the present invention: the number of the trajectory slots is three, which are distributed at 120° intervals, so that the inertial force system of the three moving parts satisfies the static equilibrium condition.

[0013] As a further aspect of the present invention: in step S1, when adjusting the position of the soft claw, the moving part should be positioned in the appropriate position of the entire track groove to prevent false pressure from occurring at both ends of the track groove.

[0014] As a further aspect of the present invention: in step S2, the limiting screw is first screwed into the movable pin, and then the limiting pin is inserted into the track groove from the side of the clamp body away from the soft claw.

[0015] The beneficial effects of this invention are as follows: This fixture eliminates the "tool deflection" phenomenon caused by the fit clearance between the soft jaw and the chuck base in traditional methods. Before turning, under the action of the tangential inertial force of the chuck, the moving part gradually moves along the motion trajectory of the track groove in the direction where the diameter tends to decrease, satisfying automatic clamping and centering. The soft jaw is forcibly locked under the action of strong rotational inertial force, the clearance is eliminated, and a high-rigidity state is formed, thereby ensuring that the contour of the turned soft jaw is real and accurate, providing a reliable accuracy benchmark for subsequent workpiece processing. Secondly, by using this fixture, the dependence on high-precision cylindrical bars is eliminated. The fixture itself constitutes the centering benchmark, so that the factory no longer needs to prepare and manage a series of bars of different diameters, which significantly reduces material and storage costs, simplifies the operation process, and improves production efficiency and economy. Attached Figure Description

[0016] The invention will now be further described with reference to the accompanying drawings.

[0017] Figure 1 This is a side view of a CNC lathe soft jaw turning fixture according to an embodiment of the present invention; Figure 2 This is a top view schematic diagram of a CNC lathe soft jaw turning fixture according to an embodiment of the present invention; Figure 3 This is a top view of the overall structure of the CNC lathe soft jaw turning fixture according to an embodiment of the present invention; Figure 4 This is a flowchart illustrating the steps of the soft claw self-centering method according to an embodiment of the present invention.

[0018] Explanation of reference numerals in the attached drawings: 1. Assembly slot; 2. Fixture body; 21. Track slot; 3. Moving part; 22. Through hole; 31. Movable pin; 32. Limit screw. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] See Figures 1-3 This invention discloses a CNC lathe soft jaw turning fixture for driving a soft jaw mounted on a chuck to perform centripetal motion. The fixture includes: an assembly groove 1 located on the side of the soft jaw away from the chuck; a fixture body 2 with three trajectory grooves 21 spaced at 120° intervals around the central axis of the fixture body 2; and three movable members 3 detachably mounted in the assembly groove 1, each movable member 3 movably connected to the trajectory grooves 21 and passing through the trajectory grooves 21 to axially limit the fixture body 2 on the movable body. When the chuck rotates, the trajectory grooves 21 are configured to constrain the three movable members 3, driving them to generate centripetal displacement along the trajectory grooves 21 to achieve automatic clamping and centering of the soft jaw.

[0021] Specifically, the operator aligns the fixture body 2 with the three soft jaws already mounted on the chuck, and manually rotates the fixture body 2 so that the three track grooves 21 on it are roughly aligned with the assembly grooves 1 on the back of the soft jaws. The movable part 3 passes through the track grooves 21 and is fixed in the assembly grooves 1 of the soft jaws, thus assembling the fixture body 2 and the soft jaws into a whole. After starting the lathe spindle, the rotation of the chuck drives the entire fixture to rotate. Under the action of inertial force, the movable part 3 is constrained by the track grooves 21, driving the three soft jaws to move synchronously to the center, automatically clamping and centering. At this time, the soft jaws can be turned. After machining is completed, the machine is stopped and the fixture is removed.

[0022] Furthermore, when the chuck rotates, the moving part 3 generates a strong centrifugal tendency, but this movement is restricted by the side wall of the track groove 21. The geometry of the track groove 21 is precisely designed to decompose the centrifugal force of the moving part 3 and convert it into a precisely guided centripetal force, thereby pushing the soft jaws to tighten towards the center through the moving part 3. The three track grooves 21, which are distributed at 120° intervals, ensure the synchronization and symmetry of the movement of the three soft jaws, and finally make the center of the soft jaws automatically coincide with the rotation center of the machine tool spindle, thus achieving automatic centering.

[0023] This fixture eliminates the "tool deflection" phenomenon caused by the fit clearance between the soft jaws and the chuck base in traditional methods. Before turning, under the action of the tangential inertial force of the chuck, the moving part 3 gradually moves along the movement trajectory of the track groove 21 in the direction where the diameter tends to decrease, satisfying automatic clamping and centering. The soft jaws are forcibly locked under the action of strong rotational inertial force, the clearance is eliminated, and a high-rigidity state is formed, thereby ensuring that the contour of the turned soft jaws is real and accurate, providing a reliable accuracy benchmark for subsequent workpiece machining. Secondly, by using this fixture, the dependence on high-precision cylindrical bars is eliminated. The fixture itself constitutes the centering benchmark, so that the factory no longer needs to prepare and manage a series of bars of different diameters, which significantly reduces material and storage costs, simplifies the operation process, and improves production efficiency and economy.

[0024] See Figures 2-3 Optionally, the contour curve equation of the trajectory groove 21 is defined by the self-centering trajectory equation, which is: Where ρ is the instantaneous radius of curvature of moving part 3, R is the initial radius of moving part 3, and υ is the linear velocity of moving part 3. Let ω be the angle through which the chuck rotates, and ω be the angular velocity of the chuck.

[0025] In this embodiment, the equation defines the motion path of the movable part 3 in the track groove 21, ensuring that the movable part 3 moves centripetally with a predetermined radius of curvature during the rotation of the chuck, thereby achieving precise self-centering motion.

[0026] See Figures 1-3 Optionally, the clamping body 2 has a through hole 22 in the middle for soft jaw cutting.

[0027] In this embodiment, the through hole 22 provides operating space for the turning tool, allowing the tool to directly contact the surface to be machined by the soft jaw, while avoiding interference between the clamping body 2 and the tool.

[0028] See Figures 1-2 Optionally, the movable part 3 includes a movable pin 31 that is detachably installed in the assembly groove 1, and a limiting screw 32 that is detachably installed on the side of the movable pin 31 away from the chuck. The limiting screw 32 is used to limit the clamp body 2 axially. The assembly groove 1 is a countersunk hole for screws on the soft chuck. The movable pin 31 is threaded into the assembly groove 1, and the limiting screw 32 is threaded into the movable pin 31.

[0029] In this embodiment, the limiting screw 32 fixes the movable pin 31 by threaded connection and restricts the axial displacement of the clamp body 2, ensuring that the clamp remains stable when the chuck rotates. The three movable pins 31 are threaded into the mounting groove 1 (i.e., the screw countersunk hole on the soft claw) on the corresponding soft claw, so that the movable pin 31 transmits the centripetal motion to the soft claw. The threaded connection method allows for quick replacement or adjustment of the movable part 3.

[0030] See Figures 1-3 Optionally, the radius of the through hole 22 is set to the minimum value under the premise of satisfying the condition of no interference between the turning tool and the tool.

[0031] In this embodiment, the radius of the through hole 22 is taken to the minimum value under the premise of satisfying the condition of no interference with the tool, so as to improve the mass of the fixture body 2, increase the moment of inertia, and thus enhance the clamping performance of the fixture body 2.

[0032] See Figures 1-4An embodiment of the present invention provides a self-centering method for soft jaws, using any of the CNC lathe soft jaw turning fixtures described above, comprising the following steps: S1: Adjusting the radial position of the soft jaws on the jaw base according to the diameter of the workpiece to be processed; S2: Installing the fixture body 2 onto the soft jaws, and manually rotating the fixture body 2 so that the three movable parts 3 are respectively aligned with the mounting slots 1 on the three soft jaws; S3: Passing the movable parts 3 through the track grooves 21 on the fixture body 2 and then inserting and fixing them in the mounting slots 1 of the soft jaws; S4: Starting the lathe spindle, using the tangential inertial force of the chuck, driving the movable parts 3 to move in the centripetal direction along the track grooves 21 and automatically clamping the soft jaws; S5: Performing turning machining on the soft jaws, stopping the spindle after machining is completed, and removing the fixture body 2.

[0033] Specifically, the core of this method lies in cleverly utilizing the tangential inertial force generated by the rotation of the lathe spindle as a power source. Through the precision trajectory groove 21 pre-set on the fixture body 2, the moving part 3 is constrained and guided, and the inherent centrifugal motion of the moving part 3 is precisely converted into a controlled and synchronous centripetal displacement. This drives the three soft jaws to automatically tighten towards the center and achieve high-precision centering. This method constructs an internal centering system that does not rely on external references. Its key function is to rigidly lock the soft jaws with inertial force before turning. This not only completely eliminates the "tool deflection" phenomenon caused by the fit clearance in the traditional method, ensuring the accuracy of the soft jaw turning, but also eliminates the use of high-precision bar stock, significantly reducing material and storage costs. At the same time, it simplifies the operation process and achieves a simultaneous improvement in processing efficiency and economic benefits.

[0034] See Figures 1-4 Optionally, the movement of the movable part 3 in the trajectory slot 21 is based on the self-centering motion trajectory equation. .

[0035] In this embodiment, the equation ensures that the moving part 3 moves centripetally along a predetermined trajectory when the chuck rotates, so that the clamping process of the soft jaw conforms to the theoretical model and achieves precise control.

[0036] See Figures 1-4 Optionally, the number of track slots 21 is three, which are distributed at the same 120° angle interval, so that the inertial force system of the three moving parts 3 satisfies the static equilibrium condition.

[0037] In this embodiment, the three track grooves 21 are distributed at 120° intervals, so that the inertial force system generated by the three moving parts 3 when the chuck rotates satisfies the static balance condition, ensuring the dynamic balance and stability of the fixture when rotating at high speed.

[0038] See Figures 1-4Optionally, in step S1, when adjusting the position of the soft claw, the movable part 3 should be positioned in the middle of the entire track groove 21 to prevent false pressure from occurring at both ends of the track groove 21 (although the movable pin 31 contacts the soft claw, the inertial force is not effectively converted into clamping force, causing the soft claw to loosen and the tool to deflect during cutting).

[0039] In this embodiment, when adjusting the position of the soft jaw, the movable pin 31 should be positioned in the middle of the track groove 21 to ensure that it has sufficient tangential inertial force to drive the stroke, while also retaining buffer margins at both ends. This prevents the starting end from slipping due to insufficient driving force and the ending end from jamming due to limit interference, so that the inertial force is completely converted into a continuous and stable clamping force, rigidly constraining the soft jaw, eliminating tool deflection and vibration, and ensuring turning accuracy.

[0040] See Figures 1-4 Optionally, in step S2, the limiting screw 32 is first screwed into the movable pin 31, and then the limiting pin is inserted into the track groove 21 from the side of the clamp body 2 away from the soft claw.

[0041] In this embodiment, the limiting screw 32 is used for axial limiting to prevent the clamp body 2 from moving axially on the movable part 3, and to ensure that the clamp remains in a fixed position when the chuck rotates.

[0042] In the description of this invention, it should be understood that the terms "upper," "lower," "left," and "right," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or a specific orientational structure and operation. Therefore, they should not be construed as limitations on the invention. Furthermore, "first" and "second" are only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "multiple" means two or more.

[0043] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A CNC lathe soft jaw turning fixture, used to drive a soft jaw mounted on a chuck to perform centripetal motion, characterized in that, include: Assembly slot (1) is located on the side of the soft claw away from the chuck; The clamp body (2) has three track grooves (21) on it. The three track grooves (21) are distributed at the same angle of 120° with the central axis of the clamp body (2) as the center. The movable part (3) is detachably installed in the assembly slot (1). There are three movable parts (3). The movable parts (3) are movably connected in the track slot (21). The movable parts (3) pass through the track slot (21) to axially limit the clamping body (2) on the movable body. When the chuck rotates, the track groove (21) is configured to drive the three movable parts (3) to generate centripetal displacement along the track groove (21) to achieve automatic clamping and centering of the soft jaws by constraining the three movable parts (3).

2. The CNC lathe soft jaw turning fixture according to claim 1, characterized in that, The contour curve equation of the trajectory groove (21) is defined by the self-centering trajectory equation, which is: Where ρ is the instantaneous radius of curvature of the moving part (3), R is the initial radius of the moving part (3), and υ is the linear velocity of the moving part (3). Let ω be the angle through which the chuck rotates, and ω be the angular velocity of the chuck.

3. The CNC lathe soft jaw turning fixture according to claim 2, characterized in that, The clamping body (2) has a through hole (22) in the middle for soft claw cutting.

4. The CNC lathe soft jaw turning fixture according to claim 3, characterized in that, The movable part (3) includes a movable pin (31) that is detachably installed in the assembly slot (1) and a limiting screw (32) that is detachably installed on the side of the movable pin (31) away from the chuck, the limiting screw (32) being used to axially limit the clamp body (2). The assembly groove (1) is a countersunk hole for screws on the soft claw. The movable pin (31) is threaded into the assembly groove (1), and the limiting screw (32) is threaded onto the movable pin (31).

5. The CNC lathe soft jaw turning fixture according to claim 4, characterized in that, The radius of the through hole (22) is set to the minimum value under the premise of satisfying the condition of no interference between the turning tool and the tool.

6. A method for self-centering of soft jaws, using a CNC lathe soft jaw turning fixture as described in any one of claims 3-5, characterized in that, Includes the following steps: S1: Adjust the radial position of the soft jaws on the jaw base according to the diameter of the part to be processed; S2: Install the clamping body (2) onto the soft claw, and manually rotate the clamping body (2) so that the three movable parts (3) are respectively aligned with the assembly slots (1) on the three soft claws; S3: Pass the movable part (3) through the track groove (21) on the clamp body (2) and then insert and fix it in the assembly groove (1) of the soft claw; S4: Start the lathe spindle and use the tangential inertial force of the chuck to drive the moving part (3) to move in the centripetal direction along the track groove (21) and automatically clamp the soft jaw; S5: Perform turning on the soft jaw. After machining, stop the spindle and remove the fixture body (2).

7. The self-centering method for soft grippers according to claim 6, characterized in that, The movement of the movable part (3) in the trajectory slot (21) is based on the self-centering motion trajectory equation. control.

8. The self-centering method for soft claws according to claim 7, characterized in that, The number of the trajectory slots (21) is three, which are distributed at the same 120° angle interval, so that the inertial force system of the three moving parts (3) satisfies the static equilibrium condition.

9. The self-centering method for soft claws according to claim 8, characterized in that, In step S1, when adjusting the position of the soft claw, the moving part (3) should be positioned in the middle of the entire track groove (21) to prevent false pressure from occurring at both ends of the track groove (21).

10. The self-centering method for soft claws according to claim 9, characterized in that, In step S2, first screw the limiting screw (32) into the movable pin (31), and then insert the limiting pin into the track groove (21) from the side of the clamp body (2) away from the soft claw.

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