Clamp for machine tool machining collet

Abstract

The invention belongs to the technical field of intelligent machining, and discloses a clamp for a machine tool machining collet chuck, which comprises a chuck for clamping one end of a workpiece and a support frame arranged at the other end of the workpiece, at least two rollers are arranged on the support frame, each roller is provided with a linear moving part, and rotating joints are arranged at the two ends of the axis of each roller; the rotating joints are arranged at the two ends of the roller, and the vertical position of the roller is controlled independently or in a linkage mode through the linear moving component, so that the axis of the roller can dynamically adjust the space posture according to the geometrical shape of a workpiece supporting area. When the cylindrical section is supported, the axis of the roller is parallel to the axis of the workpiece to form stable linear contact in the generatrix direction; and when the conical surface section is supported, the axis of the roller is inclined to an angle matched with the half cone angle of the outer conical surface of the collet chuck, so that axial continuous or approximately continuous linear contact is realized.

Description

Technical Field

[0001] This invention belongs to the field of intelligent machining technology, and specifically relates to a clamp for machine tool processing collets. Background Technology

[0002] Collets are typically sleeve-shaped structures with a standard conical outer surface and an inner hole for holding tools or workpieces. Multiple elastic grooves are formed along the axial direction. During operation, the collet is pressed into the matching conical hole of the spindle. The conical surface cooperation converts the axial pressure into a uniform radial clamping force, thereby achieving high coaxiality and high repeatability of tool clamping. Currently, the collet body manufacturing process commonly employs a clamping method where "one end is clamped and fixed by a chuck or special chuck head, and the other end is supported by rollers." However, this traditional clamping scheme has the following technical bottlenecks in practical applications: Conventional support rollers typically employ a standard cylindrical structure, resulting in only point contact or extremely short line contact when in contact with the outer surface of the tapered collet, leading to high stress concentration in the contact area. This non-ideal contact state not only easily scratches the finely ground tapered surface but also results in insufficient support rigidity, making the roller prone to jumping, slipping, or even localized crushing under cutting excitation.

[0003] More importantly, when processing collets of different specifications, although their taper is similar, their large end diameters differ significantly. General-purpose rollers cannot adapt to changes in the geometric shape of the tapered surface, often requiring manual replacement of roller assemblies or repeated adjustment of support height, which seriously affects production efficiency and automation level. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a clamp for machining collets on machine tools to solve the problems existing in the background art.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is a clamping fixture for machine tool processing, including a chuck for clamping one end of a workpiece and a support frame disposed at the other end of the workpiece. The support frame is provided with at least two rollers, each roller equipped with a linear motion component. Each roller has a rotating joint at both ends of its own axis, and the connection between the linear motion component and the roller is achieved through the rotating joints. The linear motion component drives the corresponding rotating joint to move vertically, thereby controlling the relative position of the rotating joints at both ends of the same roller in the vertical direction, and thus adjusting the tilt attitude of the roller axis in space. When the area to be supported in the collet is a cylindrical section, the linear movement component is adjusted to bring the rotating joints at both ends of the roller to the same horizontal height, making the roller axis parallel to the workpiece axis, so that the outer circle of the roller and the cylindrical surface of the workpiece form a stable line contact along the generatrix direction, providing uniform support force. When the area to be supported is located in the conical section of the collet, the linear movement component is adjusted to make the roller axis form an inclination angle relative to the workpiece axis. The inclination angle matches the half-cone angle of the outer conical surface of the collet to be processed, so that the outer circle of the roller and the conical surface form a continuous or nearly continuous line contact along the axial direction, increasing the contact area and reducing the local contact pressure.

[0006] Preferably, the support frame further includes a mounting frame, and the linear moving component is disposed on the mounting frame; the rotating joint includes a fixed end and a rotating end, the fixed end is rotatably connected to the shaft end of the roller, and the rotating end is defined as a first rotating end and a second rotating end according to its position in the axial direction of the roller.

[0007] Furthermore, for any of the rollers, at least one end of the first rotating end and the second rotating end is connected to the linear motion component; the linear motion component can independently adjust the position of the connected rotating joint in the vertical direction, thereby achieving precise control of the tilt angle of the roller axis relative to the workpiece axis.

[0008] Furthermore, for the same roller, the first rotating end and the second rotating end are respectively connected to mutually independent linear moving components; the two linear moving components can adjust the vertical height of their respective corresponding rotating joints, so that the tilt angle of the roller axis can be flexibly and accurately matched according to the half-cone angle of the outer conical surface of different specifications of collets, thereby improving the general adaptability of the fixture to various types and multi-tapered collet workpieces.

[0009] Furthermore, for the same roller, the first rotating end and the second rotating end are respectively connected to the first rack and the second rack; the first rack and the second rack are slidably mounted on the mounting frame in the vertical direction, and their tooth surfaces are arranged opposite each other; a control gear is provided between the first rack and the second rack, and the control gear meshes with both the first rack and the second rack to form a differential linkage mechanism; the control gear and the linear motion component are rotatably connected, and the linear motion component drives the control gear to move towards the workpiece. When only one end of the roller initially contacts the conical surface of the workpiece, the rack connected to the contact end is temporarily kept in a fixed position due to obstruction. The linear motion component continues to push the control gear towards the workpiece, forcing the control gear to rotate around its own axis during translation, thereby driving the rack at the other uncontacted end to move in the vertical direction, so that the other end of the roller then contacts the surface of the workpiece, realizing adaptive contact and stable support of both ends of the roller to the conical section of the collet.

[0010] Furthermore, the support frame also includes a base, and the mounting frame is slidably disposed on the base in a direction parallel to the workpiece axis; an elastic element is disposed between the mounting frame and the base, and the elastic element provides an elastic force along the sliding direction of the mounting frame; when the linear moving component drives the roller to complete the support of the workpiece, the elastic element provides a reverse buffer force, so that the entire support frame is in a flexible pre-tightened state, thereby limiting the axial and radial forces applied to the workpiece by the linear moving component through the roller, and avoiding additional stress caused by over-constraint or thermal expansion.

[0011] Furthermore, a locking component is provided between the mounting bracket and the base, which can switch between a locked state and a released state. In the locked state, the mounting bracket is fixed relative to the base to prevent displacement of the mounting bracket along the workpiece axis when the roller adjusts the axial posture, thus ensuring adjustment accuracy. In the released state, the mounting bracket can slide freely relative to the base in a direction parallel to the workpiece axis, allowing the elastic element to release the excessive force applied by the linear moving component through the micro-displacement of the mounting bracket, thus avoiding rigid over-constraint on the workpiece.

[0012] Furthermore, the locking component is a locking screw or a clamping cylinder mounted on the mounting bracket; the end of the locking screw abuts against the base side, and the clamping cylinder achieves rapid switching by switching on and off air pressure; before adjusting the roller posture, the locking component is first placed in the locked state; after the adjustment is completed, it is switched to the released state, so that the support frame enters the flexible support mode.

[0013] Preferably, the chuck includes a turntable and jaws, the jaws being evenly distributed on the turntable along the circumferential direction and capable of sliding synchronously along the radial direction of the turntable.

[0014] The main technical effects of this invention are reflected in the following aspects: This invention, by setting rotating joints at both ends of the roller and independently or in conjunction with linear moving components to control its vertical position, allows the roller axis to dynamically adjust its spatial posture according to the geometry of the workpiece support area. When supporting a cylindrical section, the roller axis is parallel to the workpiece axis, forming a stable line contact along the generatrix direction; when supporting a conical section, the roller axis is tilted to an angle matching the half-cone angle of the outer conical surface of the collet, achieving axially continuous or nearly continuous line contact. This design significantly increases the contact area, reduces local contact pressure, and avoids problems such as surface scratches, roller slippage, and insufficient support rigidity caused by traditional point contact, greatly improving processing stability and surface quality.

[0015] To address the challenge of synchronizing contact at conical surfaces, this invention introduces a differential linkage mechanism consisting of a control gear and a pair of opposing racks. When one end of the roller encounters resistance upon contact with the conical surface, the linear motion component continues to push the control gear to translate, forcing it to rotate around its own axis. This drives the rack at the other end to move in the opposite direction, automatically causing the other end of the roller to contact the workpiece. The entire process is completed entirely by mechanical feedback, improving the system's robustness under dynamic conditions such as high-speed and intermittent cutting.

[0016] This invention designs the mounting bracket to slide relative to the base along the workpiece's axis, and incorporates elastic elements (such as compression springs or disc springs) arranged along the sliding direction. After roller posture adjustment, the elastic elements provide a flexible preload, placing the support system in a "light contact, retractable" state. When the workpiece experiences slight axial displacement due to chuck clamping springback, cutting thermal expansion, or material elastic recovery, the mounting bracket can retract slightly under spring action, releasing the constraint force and preventing rigid over-positioning. This mechanism effectively prevents bending or inner hole out-of-roundness in thin-walled collets, ensuring key accuracy indicators such as outer taper roundness and runout.

[0017] By incorporating switchable locking components (such as locking screws or pneumatic clamping cylinders) between the mounting bracket and the base, this invention achieves dynamic management of the support system's operating modes: during the roller attitude adjustment phase, the locking components are in a locked state, ensuring the mounting bracket remains stationary and preventing displacement due to reaction forces during adjustment, thus guaranteeing the repeatability of the adjustment; during the machining support phase, the system switches to a released state, restoring axial floating capability and allowing the elastic elements to play a buffering role. This "rigid-flexible switching" mechanism resolves the inherent contradiction between "high rigidity" and "flexible avoidance" in traditional fixtures, significantly improving process reliability. Attached Figure Description

[0018] Figure 1 This is a structural diagram of the present invention; Figure 2 for Figure 1 Structural diagram of the chuck; Figure 3 for Figure 1Structural diagram of the central support frame; Figure 4 for Figure 1 A schematic diagram of the structure of the middle roller using the scheme of Embodiment 2; Figure 5 for Figure 1 A schematic diagram of the structure of the middle roller according to Embodiment 3; In the diagram: 1. Chuck; 11. Turntable; 12. Claw; 2. Support frame; 21. Roller; 22. Rotary joint; 23. Linear movement component; 24. First rack; 25. Second rack; 26. Control gear; 27. Mounting bracket; 28. Base. Detailed Implementation

[0019] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, so as to make the technical solution of the present invention easier to understand and master. In the embodiments, it should be understood that the terms "middle," "upper," "lower," "top," "right side," "left end," "above," "back," "center," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, unless otherwise specified in this specific embodiment, the connection or fixing method between components can be achieved by bolt fixing, pin fixing, or pin connection commonly used in the prior art, etc., and therefore will not be described in detail in this embodiment.

[0020] The machine tool collet clamp provided by this invention is mainly used on horizontal lathes or milling machines for grooving, external taper grinding, or end face finishing of ER, TG, and other series collets. However, its technical principle is not limited to this. The technical solution of this invention can be applied to any machining scenario involving high-precision, flexible support for thin-walled sleeve-type workpieces with conical or cylindrical outer contours.

[0021] Furthermore, those skilled in the art should understand that the chuck 1 (including the turntable 11, radial synchronous sliding jaws 12, and bevel gear drive mechanism), linear movement component 23 (such as an electric push rod, ball screw slide), rotary joint 22 (such as a universal joint, ball joint, or pin connection), locking screw, pneumatic clamping cylinder, and other structures described above are all conventional technical means in the field of mechanical fixtures. Their specific structure, working principle, and installation method have been fully disclosed in the prior art, for example, see the "Machine Tool Fixture Design Manual" or general CNC machine tool accessory standards. Therefore, this article will not elaborate on the details one by one, but only describes the parts directly related to the innovation of this invention.

[0022] Example 1 This embodiment provides a special fixture for machining collets on a machine tool, including a chuck 1 located at the end of the machine tool spindle and a support frame 2 located at the other end of the workpiece. Similar to conventional machine tools, see [link to documentation]. Figure 2 The chuck 1 includes a turntable 11 and multiple jaws 12. The jaws 12 are evenly distributed on the turntable 11 along the circumferential direction and can slide synchronously along the radial direction of the turntable 11. This synchronous sliding can be achieved by a built-in bevel gear mechanism or an external hydraulic / pneumatic drive, thereby completing the self-centering clamping of one end of the collet and ensuring high coaxiality and repeatability during the clamping process.

[0023] Preferred, see Figure 1 , Figure 3 To address the problems of poor support contact, stress concentration, and poor adaptability mentioned in the background art, this embodiment provides a dedicated support frame 2 at the free end of the workpiece. At least two rollers 21 are mounted on the support frame 2, and each roller 21 has a rotating joint 22 at both ends of its own axis. The rotating joint 22 consists of a fixed end and a rotating end: the fixed end is rotatably connected to the shaft end of the roller 21 via a bearing to ensure that the roller 21 can rotate freely; the rotating end is defined as the first rotating end and the second rotating end according to its position along the axial direction of the roller 21. The first rotating end and the second rotating end are connected to the corresponding linear motion component 23 (such as a precision electric actuator, servo screw slide, or manual fine-tuning mechanism) via a hinge structure or universal joint, allowing the roller 21 to maintain free rotation while its spatial orientation along its axis can be actively adjusted. The specific operation is as follows: When the area to be supported is the cylindrical section of the collet, the control system drives the linear movement component 23 to make the rotating ends of the roller 21 at the same vertical height, thereby making the axis of the roller 21 strictly parallel to the axis of the workpiece, and the outer circle of the roller 21 forms a stable line contact with the surface of the workpiece along the generatrix direction, providing uniform and high-rigidity radial support.

[0024] When the area to be supported is a standard conical section, the linear moving component 23 adjusts the relative height of the two rotating ends so that the axis of the roller 21 is tilted at an angle relative to the axis of the workpiece. This angle precisely matches the half-cone angle of the outer conical surface of the collet. At this time, the outer circle of the roller 21 and the conical surface form a continuous or nearly continuous line contact along the axial direction, significantly increasing the contact area and reducing the local contact pressure by more than 60%, effectively avoiding scratches, slippage, or crushing.

[0025] Furthermore, the support frame 2 includes a mounting frame 27 and a base 28. The mounting frame 27 is slidably disposed on the base 28 in a direction parallel to the workpiece axis, and an elastic element (such as a compression spring or disc spring) is provided between the two, with the elastic force direction parallel to the sliding direction of the mounting frame 27. After the roller 21 completes the posture adjustment and fits against the workpiece, the elastic element provides a reverse buffering force, so that the entire support system is in a flexible pre-tightened state, which can maintain contact and automatically retract when the workpiece undergoes axial displacement due to thermal expansion or clamping fine adjustment, avoiding over-positioning and introducing additional bending moment.

[0026] In addition, a locking component is provided between the mounting bracket 27 and the base 28 to switch the working state of the support bracket 2 between the "adjustment mode" and the "processing support mode". The locking component can adopt any locking structure applicable to linear sliding pairs in the prior art, such as locking screws, pneumatic clamping cylinders, hydraulic locking blocks, eccentric cam locking mechanisms or electromagnetic braking devices, etc.

[0027] Before the roller 21 is tilted, the operator (or the automatic control system) switches the locking mechanism to the locked state, fixing the mounting bracket 27 relative to the base 28. In this state, even if the linear motion component 23 applies an adjustment force or the roller 21 contacts the workpiece and generates a reaction force, the mounting bracket 27 will not shift axially, thus ensuring the repeatability and stability of the roller 21's attitude adjustment. After the roller 21 completes the contact adjustment with the collet's conical or cylindrical section, the locking mechanism is switched to the released state, releasing the constraint on the mounting bracket 27. At this time, the mounting bracket 27 can move freely in a direction parallel to the workpiece axis under the action of the elastic element, and the support system enters a flexible support mode. This mode allows the fixture to adapt to the small axial displacement of the workpiece caused by thermal expansion, elastic recovery, or clamping errors during processing, effectively avoiding additional stress or deformation caused by over-positioning.

[0028] It should be noted that although there are many mature solutions in the mechanical field for the locking structure between the slider and the slide rail (such as wedge locking, set screw locking, and pneumatic-hydraulic pressurized clamping), the core of this invention does not lie in the specific implementation of the locking component, but in achieving a collaborative working mechanism of "rigid positioning during adjustment and flexible avoidance during processing" by switching between locking / releasing states. Therefore, any locking structure that can achieve the above functions should be considered an equivalent implementation of this invention.

[0029] Example 2 Based on Embodiment 1, this embodiment further optimizes the adjustment accuracy and adaptability of the spatial attitude of the roller 21 axis. Specifically, Firstly, in a preferred but non-limiting configuration, for any roller 21, its first rotating end is connected to a linear motion component 23 (such as a precision electric actuator or fine-tuning screw), while the second rotating end is directly hinged to the mounting bracket 27 without an active drive mechanism. In this case, the tilt attitude of the roller 21 axis is controlled solely by the vertical displacement of the first rotating end, with the second rotating end acting as a fulcrum for rotation. This structure is suitable for batch processing scenarios of collets with relatively fixed taper specifications, and has the advantages of simple structure, low cost, and convenient maintenance. Although it is a single-sided drive, the roller 21 can still achieve adaptive tilt angle adjustment within a certain range due to the universal joint design of the rotating joint 22, avoiding rigid interference.

[0030] Further, see Figure 4 To achieve higher precision and greater versatility, this embodiment provides a dual independent drive mode: the first and second rotating ends of the same roller 21 are respectively connected to mutually independent linear motion components 23. The two linear motion components 23 (e.g., two servo electric actuators or precision slides with position feedback) can independently control the vertical height of their respective rotating ends, without coupling. The advantage lies in the fact that for different specifications of collets, the large end diameter varies significantly, resulting in different contact point heights of the roller 21 at the same tilt angle.

[0031] Example 3 This embodiment introduces a mechanical adaptive mechanism to reduce dependence on the control system and improve response speed. Specifically: See Figure 5 For the same roller 21, its first rotating end and second rotating end are rigidly connected to the first rack 24 and the second rack 25, respectively. The two racks are slidably mounted on the guide rail of the mounting bracket 27 in the vertical direction, with their tooth surfaces arranged opposite to each other. A control gear 26 is provided between them, which meshes with both racks simultaneously to form a differential linkage mechanism.

[0032] The control gear 26 is rotatably connected to a single linear motion component 23 (such as a cylinder piston rod) via a swing arm or connecting shaft. During operation, the linear motion component 23 pushes the control gear 26 to translate towards the workpiece. If only one end (e.g., the upper end) of the roller 21 contacts the conical surface first, the rack at that end is obstructed and cannot descend. Meanwhile, the control gear 26 is forced to rotate around its own axis during continued translation, thereby driving the rack at the other end (lower end) to move downwards, causing the lower end of the roller 21 to automatically contact the conical surface. When only one end of the roller 21 initially contacts the workpiece conical surface, the rack connected to the contact end remains temporarily in place due to obstruction. The linear motion component 23 continues to push the control gear 26 towards the workpiece, forcing the control gear 26 to rotate around its own axis during translation, thereby driving the rack at the other uncontacted end to move vertically, causing the other end of the roller 21 to subsequently contact the workpiece surface, achieving adaptive contact and stable support between the two ends of the roller 21 and the collet conical surface section.

[0033] Of course, the above are just typical examples of the present invention. In addition, the present invention may have many other specific embodiments. All technical solutions formed by equivalent substitution or equivalent transformation fall within the scope of protection claimed by the present invention.

Claims

1. A clamping fixture for machining collets on a machine tool, characterized in that, The device includes a chuck for clamping one end of a workpiece and a support frame located at the other end of the workpiece. The support frame is equipped with at least two rollers, each roller having a linear motion component. Each roller has a rotating joint at both ends of its own axis, through which the linear motion component and the roller are connected. The linear motion component drives the corresponding rotating joint to move vertically, thereby controlling the relative position of the rotating joints at both ends of the same roller in the vertical direction, and thus adjusting the tilt of the roller axis in space. When the area to be supported by the collet to be processed is a cylindrical section, the linear movement component is adjusted so that the rotating joints at both ends of the roller are at the same horizontal height, so that the roller axis is parallel to the workpiece axis, and the outer circle of the roller and the cylindrical surface of the workpiece form a stable line contact along the generatrix direction, providing uniform support force. When the area to be supported is located on the conical section of the collet, the linear movement component is adjusted to make the roller axis tilted relative to the workpiece axis. The tilt angle matches the half-cone angle of the outer conical surface of the collet to be processed, thereby making the outer circle of the roller and the conical surface form a continuous or nearly continuous line contact along the axial direction, increasing the contact area and reducing the local contact pressure.

2. The machine tool processing collet fixture as described in claim 1, characterized in that, The support frame also includes a mounting frame, and the linear moving component is disposed on the mounting frame; The rotating joint includes a fixed end and a rotating end. The fixed end is rotatably connected to the shaft end of the roller. The rotating end is defined as the first rotating end and the second rotating end according to its position in the axial direction of the roller.

3. The machine tool processing collet fixture as described in claim 2, characterized in that, For any of the rollers, at least one of the first rotating end and the second rotating end is connected to the linear motion component; The linear motion component can independently adjust the position of the connected rotary joint in the vertical direction, thereby achieving precise control of the tilt angle of the roller axis relative to the workpiece axis.

4. The machine tool processing collet fixture as described in claim 3, characterized in that, For the same roller, the first rotating end and the second rotating end are respectively connected to mutually independent linear moving components; The two linear moving parts can adjust the vertical height of their respective rotating joints, so that the tilt angle of the roller axis can be flexibly and accurately matched according to the half cone angle of the outer cone surface of different specifications of collets, thereby improving the general adaptability of the fixture to a variety of collet workpieces with multiple tapers.

5. The machine tool processing collet fixture as described in claim 2, characterized in that, For the same roller, the first rotating end and the second rotating end are respectively connected to the first rack and the second rack; The first and second racks are slidably mounted on the mounting bracket in a vertical direction, and their tooth surfaces are arranged opposite each other. A control gear is provided between the first rack and the second rack, and the control gear meshes with both the first rack and the second rack to form a differential linkage mechanism. The control gear and the linear motion component are rotatably connected, and the linear motion component drives the control gear to move in the direction of the workpiece. When only one end of the roller initially contacts the conical surface of the workpiece, the rack connected to the contact end remains in a fixed position due to obstruction. The linear movement component continues to push the control gear toward the workpiece, forcing the control gear to rotate around its own axis during translation, thereby driving the rack at the other uncontacted end to move in the vertical direction, so that the other end of the roller comes into contact with the workpiece surface, achieving adaptive contact and stable support of both ends of the roller to the conical section of the collet.

6. The machine tool machining collet fixture as described in any one of claims 2 to 5, characterized in that, The support frame also includes a base, and the mounting frame is slidably disposed on the base in a direction parallel to the workpiece axis; An elastic element is provided between the mounting bracket and the base, and the elastic element provides an elastic force along the sliding direction of the mounting bracket; After the linear moving component drives the roller to support the workpiece, the elastic element provides a reverse buffer force, so that the entire support frame is in a flexible pre-tightened state, thereby limiting the axial and radial forces applied to the workpiece by the linear moving component through the roller, and avoiding additional stress caused by over-constraint or thermal expansion.

7. The machine tool processing collet fixture as described in claim 6, characterized in that, A locking component is also provided between the mounting bracket and the base, and the locking component can switch between a locked state and a released state. In the locked state, the mounting bracket is fixed relative to the base to prevent displacement of the mounting bracket along the workpiece axis when the roller is adjusted in axial posture, thus ensuring adjustment accuracy; In the released state, the mounting bracket can slide freely relative to the base in a direction parallel to the workpiece axis, allowing the elastic element to release the excessive force applied by the linear moving component through the micro-displacement of the mounting bracket, thus avoiding rigid over-constraint on the workpiece.

8. The machine tool processing collet fixture as described in claim 7, characterized in that, The locking component is a locking screw or a clamping cylinder mounted on the mounting bracket; The end of the locking screw abuts against the base side, and the clamping cylinder achieves rapid switching by switching on and off air pressure; Before adjusting the roller posture, first put the locking component in the locked state; after the adjustment is completed, switch to the released state to put the support frame into the flexible support mode.

9. The machine tool machining collet fixture as described in any one of claims 1 to 5, characterized in that, The chuck includes a turntable and jaws. The jaws are evenly distributed on the turntable along the circumferential direction and can slide synchronously along the radial direction of the turntable.

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