Self-positioning variable angle chuck for processing worm by CNC milling machine

Abstract

The utility model discloses a kind of self-positioning variable-angle chuck for CNC milling machine processing worm, comprising: chuck body, the front end of the chuck body is equipped with the clamping part for clamping workpiece, rear end is equipped with the installation part for being connected with machine tool spindle;The outer peripheral wall of the installation part is equipped with several circumferentially distributed opening positioning key groove, the opening positioning key groove is matched with the positioning key inside the machine tool spindle, and the concentricity of the chuck body is adjusted by rotating the chuck body to select different opening positioning key groove and the machine tool spindle matched installation;The central axis of the chuck body is inwardly provided with through-hole, the positioning rod is fixedly arranged in the through-hole, the front end of the positioning rod extends into the area of the clamping part, and contacts the one end of workpiece entering the clamping part. The utility model is ingenious, separates and combines the rotatable compensation clamping function of vulnerable positioning function, greatly improves processing precision, production efficiency and fixture economy.

Description

Technical Field

[0001] This utility model relates to the field of machining fixture technology, and in particular to a self-positioning variable angle chuck for machining worm gears on a CNC milling machine. Background Technology

[0002] When machining long-shaft worm gears on a CNC milling machine, extremely high requirements are placed on the repeatability of workpiece positioning and the concentricity of clamping. Existing technologies typically use ordinary spring collets or three-jaw chucks, which have significant drawbacks: 1) Poor repeatability leads to out-of-tolerance starting positions of the worm gear helix, resulting in a high product scrap rate; 2) The collet itself and the mating surfaces connecting to the spindle are prone to wear, causing the clamping center to deviate, resulting in workpiece misalignment or collisions during machining, short collet life, and frequent replacements. This not only increases fixture costs but also leads to long downtime for sorting and adjustments, resulting in low production efficiency. Utility Model Content

[0003] The purpose of this invention is to overcome the shortcomings of the above-mentioned background technology and provide a self-positioning variable angle chuck for CNC milling worm gears with long service life and high repeatability.

[0004] To achieve the above objectives, this utility model provides the following technical solution: A self-positioning variable angle chuck for machining worm gears on a CNC milling machine, comprising: The chuck body has a clamping part at the front end for clamping the workpiece and a mounting part at the rear end for connecting with the machine tool spindle. The outer peripheral wall of the mounting part is provided with a plurality of circumferentially distributed open positioning keyways. The open positioning keyways cooperate with the positioning key inside the machine tool spindle. The concentricity of the chuck body can be adjusted by rotating the chuck body to select different open positioning keyways to cooperate with the machine tool spindle. The chuck body has a through hole in its central axis, and a chuck positioning rod is fixedly installed in the through hole. The front end of the chuck positioning rod extends into the area of ​​the clamping part and contacts one end of the workpiece that enters the clamping part.

[0005] Preferably, the rear end of the chuck body is connected to the machine tool spindle via a pull tube, and the pull tube is connected to the mounting part at the rear end of the chuck body via a threaded connection.

[0006] The present invention further includes a positioning device that works in conjunction with the chuck body. The positioning device is mounted on the machine tool worktable and located directly in front of the machine tool spindle. The slide is connected to a lead screw transmission mechanism located on the machine tool. The lead screw transmission mechanism is driven by a servo motor mounted on the machine tool and is used to move the slide towards or away from the machine tool spindle.

[0007] Preferably, the positioning device includes a support base, on which a bushing is provided for guiding and supporting the movement of the workpiece. In use, the clamping part of the chuck body, the chuck positioning rod, and the bushing are located on the same center line.

[0008] Preferably, the rear end of the bushing is provided with a positioning fixture, the positioning fixture including a floating positioning rod, the front end of the floating positioning rod extending to the outside of the positioning device and coaxial with the bushing, and capable of contacting the other end of the workpiece; the rear end of the floating positioning rod is provided with a spring coaxial with the floating positioning rod.

[0009] Preferably, the positioning fixture further includes a locking screw, which is located behind the floating positioning rod.

[0010] The beneficial effects of this utility model are: This invention provides a self-positioning variable-angle chuck for machining worm gears on a CNC milling machine. The chuck connects to the spindle via multiple open keyways designed on its body. When the keyways wear and concentricity decreases due to prolonged use, the chuck can be rotated to replace the worn surface and reinstalled, utilizing the unworn keyway surface for mating, thereby restoring concentricity and extending the chuck's service life. During machining, a robotic arm feeds the workpiece into the loosened chuck, the support advances, and the bushing on it guides the workpiece axially until the workpiece end overcomes the spring force to push the positioning rod backward, achieving precise axial positioning. The chuck then clamps again. This process achieves fully automated, precise, and repeatable positioning, eliminating human error and ensuring product quality. This invention features an ingenious structure that separates and combines the easily damaged positioning function with the rotatable, compensated clamping function, greatly improving machining accuracy, production efficiency, and fixture economy. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the overall structure of a preferred embodiment of a self-positioning variable angle chuck for machining worm gears on a CNC milling machine according to the present invention; Figure 2 This is a schematic diagram of the chuck body of this utility model clamping the workpiece; Figure 3 yes Figure 2 The cross-sectional view of the structure shown in the figure; Figure 4 This is a schematic diagram of the structure of the chuck body shown in this utility model; Figure 5 yes Figure 4 A cross-sectional view of the chuck body shown; Figure 6 This is a schematic diagram of the tube drawing method shown in this utility model; Figure 7This is a schematic diagram of the machine tool spindle shown in this utility model; Figure 8 This is a schematic diagram of the overall structure of the positioning device shown in this utility model; Figure 9 This is a schematic diagram of the positioning fixture shown in this utility model; The components in the attached diagram are labeled as follows: 1. Chuck body; 1-1. Clamping part; 1-2. Mounting part; 1-3. Opening positioning keyway; 2. Chuck positioning rod; 3. Pull tube; 4. Machine tool spindle; 5. Positioning device; 6. Support base; 6-1. Bushing; 7. Positioning fixture; 8. Floating positioning rod; 9. Workpiece; 10. Spring; 11. Locking screw; 12. Machining tool. Detailed Implementation

[0012] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the scope of protection of the present invention.

[0013] Example: This embodiment describes the structure of a self-positioning variable angle chuck for machining worm gears on a CNC milling machine.

[0014] like Figure 1-7 As shown, Figure 1 This is a schematic diagram of the overall structure of a preferred embodiment of a self-positioning variable angle chuck for machining worm gears on a CNC milling machine. Figure 2 This is a schematic diagram of the chuck body of this utility model clamping the workpiece. Figure 3 yes Figure 2 The cross-sectional view of the structure shown is shown in the figure.

[0015] A self-positioning variable angle chuck for machining worm gears on a CNC milling machine includes: a chuck body 1 and a positioning device 5 used in conjunction with the chuck body 1. The chuck body 1 and the positioning device respectively clamp one end of a workpiece 9. In this embodiment, the front end of the chuck body 1 is provided with a clamping part 1-1 for clamping the workpiece 9, and the rear end is provided with a mounting part 1-2 for connecting to a machine tool spindle 4. The rear end of the chuck body 1 is connected to the machine tool spindle 4 through a pull tube 3. The pull tube 3 is connected to the mounting part 1-2 at the rear end of the chuck body 1 by a threaded connection. The pull tube transmits the axial tension / thrust force inside the spindle to the chuck, causing it to generate radial contraction / opening motion.

[0016] In simple terms, when a workpiece needs to be clamped, the machine tool control system issues a command, and the tensioning mechanism inside the spindle (such as a hydraulic cylinder) generates a pulling force into the spindle box. This force is transmitted through a pull tube to the chuck body, which is threaded to it. The chuck body is pulled backward, and under the strong axial tension, the elastic clamping part of the chuck body is forced to contract radially, thus firmly holding the workpiece. When it is necessary to release the workpiece, the machine tool control system issues a tool release command, and the tool release mechanism inside the spindle generates a forward thrust. This thrust is transmitted through the pull tube, pushing the chuck body forward. The clamping part opens radially due to its own elasticity, thereby releasing the workpiece.

[0017] The pull tube is installed inside the machine tool spindle. The spindle of a standard CNC milling machine has a hollow hole inside, and the spindle contains a tensioning and releasing mechanism, which is usually hydraulically or pneumatically driven. This mechanism is existing technology, well known and used by those skilled in the art. The tensioning and releasing mechanism inside the machine tool spindle and the control system that controls the clamping and releasing between the machine tool spindle and the chuck body are not the protection objects of this utility model. Therefore, they will not be described in detail. However, the absence of specific descriptions will not affect those skilled in the art's understanding and implementation of the technical solution of this utility model.

[0018] The outer peripheral wall of the mounting part 1-2 is provided with several circumferentially distributed open positioning keyways 1-3. The open positioning keyways 1-3 cooperate with the positioning key inside the machine tool spindle 4. The concentricity of the chuck body 1 can be adjusted by rotating the chuck body 1 to select different open positioning keyways 1-3 to cooperate with the machine tool spindle 4.

[0019] In this embodiment, three open locating keyways are provided on the mounting part, which can be evenly or unevenly distributed. In this embodiment, the open locating keyways on the mounting part cooperate with the locating key on the machine tool spindle. When the chuck experiences keyway wear and concentricity degradation due to long-term use, it can be rotated and reinstalled, utilizing the unworn keyway surface for engagement. This compensates for wear, adjusts concentricity, and greatly extends the effective service life of the chuck. The traditional single wear surface is transformed into three, or multiple, interchangeable wear surfaces designed according to production needs, extending the effective service life of the chuck several times over, improving the accuracy of clamping concentricity, and avoiding the problem of "product misalignment or damage due to poor concentricity."

[0020] A through hole is provided in the central axis of the chuck body 1, and a chuck positioning rod 2 is fixedly installed in the through hole. The front end of the chuck positioning rod 2 extends into the area of ​​the clamping part 1-2 and contacts one end of the workpiece 9 that enters the clamping part 1-2. The chuck positioning rod provides a fixed and precise axial positioning reference surface for the workpiece entering the clamping part.

[0021] In this embodiment, the chuck also includes a positioning device that works in conjunction with the chuck body. The figure shows the positioning device and the chuck body respectively clamping one end of the workpiece. In this invention, the purpose of providing the cooperating positioning device is to guide the workpiece to remain coaxial with the machine tool spindle center during clamping, ensuring accurate and repeatable positioning of each workpiece and eliminating positioning errors. Specifically, the positioning device 5 is installed on the machine tool worktable and located directly in front of the machine tool spindle 4. The slide is connected to a lead screw drive mechanism located on the machine tool. The lead screw drive mechanism is driven by a servo motor installed on the machine tool, used to move the slide towards or away from the machine tool spindle.

[0022] like Figure 8 , 9 As shown, the positioning device 5 includes a support base 6, on which a bushing 6-1 for guiding the movement of the workpiece is provided. In use, the clamping part 1-1 of the chuck body 1, the chuck positioning rod 2, and the bushing 6-1 are located on the same center line. A positioning fixture 7 is provided at the rear end of the bushing 6-1. The positioning fixture 7 includes a floating positioning rod 8, the front end of which extends to the outside of the positioning fixture 7 and is coaxial with the bushing 6-1, and can contact the other end of the workpiece 9. A spring 10 is provided at the rear end of the floating positioning rod 8, coaxial with the floating positioning rod 8. The positioning fixture 7 also includes a locking screw 11, located behind the floating positioning rod 8. When the floating positioning rod moves axially, the spring provides axial elastic force, and the locking screw provides a restraining effect on the spring.

[0023] In use, the front end of the floating positioning rod contacts the workpiece. The floating positioning rod, in conjunction with the bushing, ensures the coaxiality of the workpiece with the spindle center during movement, thus guiding and initially positioning the workpiece. As the slide moves, it drives the support seat towards the machine tool spindle. The spring at the rear end of the floating positioning rod provides elastic force to extend the floating positioning rod forward and allows it to retract backward when subjected to external force, achieving a buffering or floating function. The support seat moves until it stops after pressing against the chuck positioning rod and the floating positioning rod at both ends of the workpiece. At this point, the workpiece is clamped by the chuck body, and its position is determined. The support seat then retracts away from the machine tool spindle until the floating positioning rod no longer contacts the workpiece. This is to prevent friction damage between the workpiece rotation and the floating positioning rod during machining. However, the bushing still supports the workpiece to ensure that the workpiece and the machine tool spindle remain concentric during machining, providing a rigid support point for the workpiece's clamping stability, preventing workpiece deformation during machining, and improving workpiece machining quality.

[0024] Working principle: Loading: With the clamping part 1-1 in the loose state, the loading robot sends the workpiece 9 into the clamping part 1-1 of the chuck body and places it initially. The clamping part 1-1 then clamps the workpiece.

[0025] Positioning: The support seat 6 moves axially along the direction of the machine tool spindle 4. As the support seat 6 moves, the end of the workpiece 9 that remains outside the clamping part 1-1 gradually enters the bushing 6-1 and guides the support seat forward. At this time, the clamping part is in a loose state. The support seat 6 continues to move forward, carrying the workpiece 9 to press against the chuck positioning rod 2 inside the chuck body 1. When both ends of the workpiece press against the chuck positioning rod 2 and the floating positioning rod 8 respectively, the workpiece 9 has reached a precise axial positioning position.

[0026] Clamping: The chuck body 1 performs a clamping action to firmly hold the workpiece 9.

[0027] Machining: The support seat 6 retracts, moving the floating positioning rod 7 away from the workpiece to a distance where it does not contact the workpiece. The bushing 6-1 on the support seat 6 continues to support the workpiece, and the machining tool 12 on the CNC milling machine begins to machine the workpiece.

[0028] Material unloading: After processing is completed, clamping part 1-1 is released, and the material handling robot takes out the processed workpiece and continues to the next workpiece to be processed.

[0029] Through the above embodiments, this utility model achieves ultra-high repeatability of axial positioning accuracy for workpieces by cooperating with the chuck body and the positioning device. The chuck positioning rod in the chuck body provides a fixed and highly accurate axial positioning reference surface. At the same time, the support base and bushing cooperate to ensure the coaxiality of the workpiece with the spindle center during movement. The coaxial positioning of the two positioning rods ensures that no matter how many times the workpiece is changed, as long as the positioning rods at both ends are tightened, the starting position of the workpiece in the axial direction will be completely consistent, fundamentally eliminating the problem of "worm gear position (such as the starting point of the helix) out of tolerance" caused by inaccurate axial positioning. By setting an open locating keyway on the chuck body to cooperate with the locating key in the machine tool spindle, when the currently used keyway wears down and causes a decrease in concentricity, rotating the chuck body can transform the traditional single worn surface into multiple alternately usable worn surfaces, instantly obtaining a brand new, unworn keyway surface to cooperate with the spindle. This greatly improves the service life of the chuck and the accuracy of clamping concentricity, avoiding "product misalignment or damage due to poor concentricity", and significantly reducing the replacement frequency and procurement cost of the chuck.

[0030] By using this new type of chuck, the high-precision repeatability of positioning ensures stable product quality. The interchangeable wear surfaces ensure concentricity during clamping while reducing fixture wear, significantly saving labor costs and improving production efficiency. Calculations show that after using this chuck, the number of abnormal worm gear parts produced by 11 milling machines was reduced from an average of 2 per day to zero. This also saves an average of 1 hour of labor costs per day spent on sorting; this time could be used for production, increasing daily output by 1500 pieces. Furthermore, the chuck's lifespan has increased from an average of 2 months to a year, saving 132 chucks annually.

[0031] The above description is merely an embodiment of this utility model and does not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made based on the description and drawings of this utility model, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A self-positioning variable angle chuck for machining worm gears on a CNC milling machine, characterized in that, include: The chuck body (1) has a clamping part (1-1) at the front end for clamping the workpiece (9) and a mounting part (1-2) at the rear end for connecting with the machine tool spindle (4). The outer peripheral wall of the mounting part (1-2) is provided with a plurality of circumferentially distributed open positioning keyways (1-3). The open positioning keyways (1-3) cooperate with the positioning key inside the machine tool spindle (4). The concentricity of the chuck body (1) can be adjusted by rotating the chuck body (1) to select different open positioning keyways (1-3) to cooperate with the machine tool spindle (4). The chuck body (1) has a through hole in the center axis, and a chuck positioning rod (2) is fixedly installed in the through hole. The front end of the chuck positioning rod (2) extends into the area of ​​the clamping part (1-1) and contacts one end of the workpiece (9) that enters the clamping part (1-1).

2. The self-positioning variable angle chuck for machining worm gears on a CNC milling machine according to claim 1, characterized in that: The rear end of the chuck body (1) is connected to the machine tool spindle (4) via a pull tube (3), and the pull tube (3) is connected to the mounting part (1-2) at the rear end of the chuck body (1) via a threaded connection.

3. A self-positioning variable angle chuck for machining worm gears on a CNC milling machine according to claim 1, characterized in that: It also includes a positioning device (5) used in conjunction with the chuck body (1). The positioning device (5) is mounted on the slide of the machine tool and located directly in front of the machine tool spindle (4). The slide is connected to a lead screw transmission mechanism located on the machine tool. The lead screw transmission mechanism is driven by a servo motor mounted on the machine tool and is used to drive the slide to move closer to or away from the machine tool spindle (4).

4. A self-positioning variable angle chuck for machining worm gears on a CNC milling machine according to claim 3, characterized in that: The positioning device (5) includes a support base (6), on which a bushing (6-1) for guiding and supporting the workpiece is provided. When in use, the clamping part (1-1) of the chuck body (1), the positioning rod (2) and the bushing (6-1) are located on the same center line.

5. A self-positioning variable angle chuck for machining worm gears on a CNC milling machine according to claim 4, characterized in that: The bushing (6-1) has a positioning fixture (7) at its rear end. The positioning fixture (7) includes a floating positioning rod (8). The front end of the floating positioning rod (8) extends to the outside of the positioning fixture (7) and is in the same axial direction as the bushing (6-1), and can contact the other end of the workpiece (9). The rear end of the floating positioning rod (8) is provided with a spring (10) in the same axial direction as the floating positioning rod (8).

6. A self-positioning variable angle chuck for machining worm gears on a CNC milling machine according to claim 5, characterized in that: The positioning fixture (7) also includes a locking screw (11), which is located behind the floating positioning rod (8).

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