Down-draw centering tooling

Abstract

The utility model provides a kind of down centering processing fixture, it is related to machining technical field, including lathe spindle, lathe chuck and positioning disc, lathe chuck is installed on lathe spindle, lathe chuck includes chuck seat and multiple clamping jaws, each clamping jaw includes the movable clamping jaw body along the radial of lathe spindle and the clamping jaw clamping portion being set on clamping jaw body, the inner side wall of clamping jaw clamping portion is provided with the fan-shaped taper surface that is gradually expanded from top to bottom with the axis of lathe spindle as reference line;Positioning disc is used for fixed workpiece, its outer wall is provided with the annular taper surface that is gradually expanded from top to bottom with the axis of lathe spindle as reference line;When clamping jaw is radially tightened, fan-shaped taper surface and annular taper surface mutually cooperate, positioning disc is simultaneously radially clamped and positioned, and downward pull force towards chuck seat is exerted to positioning disc, so that positioning disc is automatically pulled to positioning reference surface, realize the double function of accurate positioning and axial fastening of workpiece center, improve the positioning accuracy of workpiece, so as to improve the machining accuracy of workpiece.

Description

Technical Field

[0001] This utility model relates to the field of machining technology, and in particular to a pull-down centering machining fixture. Background Technology

[0002] In the machining of precision housing parts such as automotive motor housings, the accuracy and stability of clamping and positioning directly affect the machining precision and production efficiency. With the rapid development of the automotive industry, the requirements for precision parts machining are constantly increasing, and traditional positioning fixtures can no longer meet the needs of modern production.

[0003] In the existing technology, positioning fixtures often have the problem of insufficient positioning accuracy, which leads to deviation between the workpiece center and the machine tool spindle center. The tool will be deflected during the machining process, resulting in errors in machining size and shape, which cannot meet the design requirements.

[0004] Therefore, improving positioning accuracy during workpiece processing is a technical problem that urgently needs to be solved by those in this field. Utility Model Content

[0005] This invention addresses the technical problem of improving positioning accuracy during workpiece machining in existing technologies. It provides a pull-down centering machining fixture.

[0006] A pull-down centering machining fixture, comprising: Machine tool spindle; A machine tool chuck is mounted on the machine tool spindle. The machine tool chuck includes a chuck seat and a plurality of jaws disposed on the chuck seat. Each jaw includes a jaw body that is radially movable along the machine tool spindle and a jaw clamping part disposed on the jaw body. The inner sidewall of the jaw clamping part is provided with a fan-shaped conical surface that gradually expands from top to bottom with the axis of the machine tool spindle as the reference line. The positioning plate is used to fix the workpiece, and its outer peripheral wall is provided with an annular conical surface that gradually expands from top to bottom with the axis of the machine tool spindle as the reference line. The sector-shaped conical surface and the annular conical surface cooperate with each other to achieve the downward centering of the workpiece.

[0007] Furthermore, the number of the chucks is three, and the three chucks are distributed at equal angles along the circumference of the chuck seat.

[0008] Furthermore, the sum of the actual contact areas between the annular conical surface and the three sector-shaped conical surfaces is not less than 90% of the area of ​​the annular conical surface.

[0009] Furthermore, the fan-shaped cone surface and the annular cone surface have the same semi-cone angle, which is 2 to 5 degrees.

[0010] Furthermore, the semi-cone angle is 3 degrees.

[0011] Furthermore, the pull-down centering machining fixture also includes a positioning reference surface, and the lower end surface of the positioning disk when pulled down cooperates with the positioning reference surface to define the axial reference position of the workpiece.

[0012] Furthermore, the positioning reference surface is located at the lower end of the claw clamping part on the sector-shaped conical surface.

[0013] Furthermore, the chuck holder is made of alloy steel.

[0014] Furthermore, the claw is made of 40CrNiMoA material with a hardness of 30~35HRC.

[0015] Furthermore, the workpiece is a motor housing.

[0016] Compared with the prior art, the pull-down centering machining fixture provided in this embodiment of the utility model has at least the following technical effects: The pull-down centering machining fixture includes a machine tool spindle, a machine tool chuck, and a positioning plate. The machine tool chuck is mounted on the machine tool spindle and includes a chuck seat and multiple jaws disposed on the chuck seat. Each jaw includes a jaw body that is radially movable along the machine tool spindle and a jaw clamping part disposed on the jaw body. The inner side wall of the jaw clamping part is provided with a fan-shaped conical surface that gradually expands from top to bottom with the axis of the machine tool spindle as the reference line. The positioning plate is used to fix the workpiece, and its outer peripheral wall is provided with an annular conical surface that gradually expands from top to bottom with the axis of the machine tool spindle as the reference line. When the jaws are radially tightened, the fan-shaped conical surface and the annular conical surface cooperate with each other, applying a downward pull force towards the chuck seat to the positioning plate while radially clamping the positioning plate, so that the positioning plate is automatically pulled towards the positioning reference surface, realizing the dual functions of precise positioning of the workpiece center and axial clamping, improving the positioning accuracy of the workpiece, thereby improving the machining accuracy of the workpiece. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a pull-down centering machining fixture in one embodiment of the present invention; Figure 2 for Figure 1 A schematic diagram of the cross-sectional structure; Figure 3 for Figure 2A magnified view of a portion at point A; Figure 4 This is a schematic diagram of the structure of a machine tool chuck in one embodiment of the present invention; Figure 5 for Figure 4 A schematic diagram of the cross-sectional structure; Figure 6 for Figure 5 A magnified view of a portion at point B; Figure 7 This is a schematic diagram of the positioning disk in one embodiment of the present invention; Figure 8 This is a schematic diagram of the structure of a motor housing workpiece in one embodiment of the present invention.

[0019] Reference numerals: 10, machine tool spindle; 20, machine tool chuck; 21, chuck base; 22, jaw; 221, jaw body; 222, jaw clamping part; 2221, sector-shaped conical surface; 30, positioning plate; 31, annular conical surface; 32, positioning plate body; 33, connecting hole; 34, positioning pin hole; 40, positioning reference surface; 50, motor housing workpiece; 51, mounting and fixing hole; 52, positioning hole. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly set on the other component; when a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to the other component.

[0022] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0023] In the machining of precision housing parts such as automotive motor housings, the accuracy and stability of clamping and positioning directly affect the machining precision and production efficiency. With the rapid development of the automotive industry, the requirements for precision parts machining are constantly increasing, and traditional positioning fixtures can no longer meet the needs of modern production.

[0024] In the existing technology, positioning fixtures often have the problem of insufficient positioning accuracy, which leads to deviation between the workpiece center and the machine tool spindle center. The tool will be deflected during the machining process, resulting in errors in machining size and shape, which cannot meet the design requirements.

[0025] Therefore, improving positioning accuracy during workpiece processing is a technical problem that urgently needs to be solved by those in this field.

[0026] Please refer to the attached document. Figure 1 To be continued Figure 8 As shown, one embodiment of this utility model provides a pull-down centering machining fixture, including a machine tool spindle 10, a machine tool chuck 20, and a positioning plate 30. The machine tool chuck 20 is mounted on the machine tool spindle 10 and includes a chuck base 21 and multiple jaws 22 disposed on the chuck base 21. The multiple jaws 22 can be synchronously radially extended and retracted relative to the chuck base 21. Each jaw 22 includes a jaw body 221 that is radially movable along the machine tool spindle 10 and a... The jaw clamping part 222 is provided on the jaw body 221. The inner wall of the jaw clamping part 222 is provided with a fan-shaped conical surface 2221 that gradually expands from top to bottom with the axis of the machine tool spindle 10 as the reference line. The positioning plate 30 is used to fix the workpiece, and its outer peripheral wall is provided with an annular conical surface 31 that gradually expands from top to bottom with the axis of the machine tool spindle 10 as the reference line. The fan-shaped conical surface 2221 and the annular conical surface 31 cooperate with each other to realize the downward centering of the workpiece. It should be noted that the end face and outer cylindrical surface of the positioning plate 30 are precision ground so that the flatness of the end face is controlled to ≤0.005mm and the runout of the outer cylindrical surface is controlled to ≤0.01mm. As a positioning reference for the workpiece, it can effectively eliminate cumulative errors.

[0027] In addition, the pull-down centering machining fixture also includes a drive mechanism. The drive mechanism is connected to multiple jaws 22 through a transmission component and is used to drive the multiple jaws 22 to synchronously retract and extend radially relative to the chuck seat 21, so as to ensure that the radial stroke and clamping force of each jaw 22 are basically consistent. The drive mechanism can be any one of hydraulic drive, pneumatic drive or manual drive.

[0028] When the chuck 22 tightens radially, multiple fan-shaped conical surfaces 2221 and annular conical surfaces 31 come into contact with each other. By using the slope of the conical surfaces, the radial clamping force of the chuck 22 on the positioning disk 30 is decomposed into a radial component and a downward axial component. Thus, while radially clamping the positioning disk 30, a downward pulling force towards the chuck seat 21 is applied to the positioning disk 30, so that the positioning disk 30 is automatically pulled towards the positioning reference surface 40, realizing the dual function of workpiece center positioning and axial fastening.

[0029] In this embodiment, the pull-down centering machining fixture includes a machine tool spindle 10, a machine tool chuck 20, and a positioning plate 30. The machine tool chuck 20 is mounted on the machine tool spindle 10 and includes a chuck base 21 and a plurality of jaws 22 disposed on the chuck base 21. Each jaw 22 includes a jaw body 221 that is radially movable along the machine tool spindle 10 and a jaw clamping part 222 disposed on the jaw body 221. The inner sidewall of the jaw clamping part 222 is provided with a fan-shaped conical surface 2221 that gradually expands from top to bottom with the axis of the machine tool spindle 10 as the reference line. The positioning disk 30 is used to fix the workpiece. Its outer peripheral wall is provided with an annular conical surface 31 that gradually expands from top to bottom with the axis of the machine tool spindle 10 as the reference line. When the chuck 22 tightens radially, the fan-shaped conical surface 2221 and the annular conical surface 31 cooperate with each other to apply a downward pulling force towards the chuck seat 21 to the positioning disk 30 while radially clamping it. This causes the positioning disk 30 to be automatically pulled towards the positioning reference surface 40, realizing the dual functions of precise positioning of the workpiece center and axial fastening, improving the positioning accuracy of the workpiece, thereby improving the machining accuracy of the workpiece.

[0030] In some alternative embodiments, the number of jaws 22 is three, and the three jaws are equally angularly distributed around the circumference of the chuck base 21.

[0031] In some optional embodiments, the sum of the actual contact areas between the annular conical surface 31 and the three sector-shaped conical surfaces 2221 is not less than 90% of the area of ​​the annular conical surface 31. To ensure that the sum of the actual contact areas between the annular conical surface 31 and the three sector-shaped conical surfaces 2221 is not less than 90% of the area of ​​the annular conical surface 31, the taper tolerance of the annular conical surface 31 and the sector-shaped conical surfaces 2221 needs to be controlled within ±5′.

[0032] In some optional embodiments, the sector-shaped cone 2221 and the annular cone 31 have the same semi-cone angle, which is 2 to 5 degrees. The semi-cone angle refers to the angle between the side surface of the cone and its central axis.

[0033] In some optional embodiments, the half-cone angle is 3 degrees. The 3-degree half-cone angle design ensures sufficient axial force while effectively preventing self-locking of the conical surface, thereby facilitating the smooth release of the chuck 22 after machining.

[0034] In some optional embodiments, the pull-down centering fixture further includes a positioning reference surface 40, the lower end face of the positioning disk 30 engaging with the positioning reference surface 40 when pulled down to define the axial reference position of the workpiece.

[0035] In some alternative embodiments, the positioning reference surface 40 is disposed at the lower end of the claw clamping portion 222 at the sector-shaped conical surface 2221.

[0036] In some optional embodiments, the chuck seat 21 is made of alloy steel, which has excellent strength. Using alloy steel as the material for the chuck seat 21 effectively reduces the risk of deformation of the chuck seat 21 during processing.

[0037] In some alternative embodiments, the chuck 22 is made of 40CrNiMoA and is heat-treated (such as quenching + high-temperature tempering) to make its hardness 30~35HRC, so as to ensure the wear resistance and strength of the chuck 22.

[0038] In some alternative embodiments, the workpiece can be, but is not limited to, the motor housing workpiece 50, specifically an automotive motor housing. In some other embodiments, the workpiece can also be other similar cylindrical or shell-like workpieces.

[0039] In some optional embodiments, the positioning disk 30 includes a positioning disk body 32 and a plurality of connecting holes 33. The positioning disk body 32 has a central axis. Each connecting hole 33 penetrates the positioning disk body 32 along the central axis. The plurality of connecting holes 33 are used to correspond one-to-one with the mounting holes 51 on the end face of the motor housing workpiece 50 in the installed state, and are detachably connected by connectors. The positioning disk 30 is rigidly connected to the motor housing workpiece 50 by connectors, forming an integrated structure of "workpiece-positioning disk-claw". Specifically, there are 7 connecting holes 33, which correspond one-to-one with the 7 mounting holes 51 on the end face of the motor housing workpiece 50, and are detachably connected by connectors.

[0040] The positioning plate body 32 is provided with positioning pin holes 34 along the central axis. The positioning pin holes 34 are used to cooperate with the positioning holes 52 provided on the end face of the motor housing workpiece 50 for positioning. The number of positioning pin holes 34 can be, but is not limited to, two. The positioning pin holes 34 enable the circumferential positioning accuracy of the motor housing workpiece 50 to be ≤0.02mm.

[0041] During the machining of the motor housing workpiece 50, the positioning disk 30 is directly clamped by the jaw clamping part 222 on the machine tool chuck 20, thereby achieving the positioning of the motor housing workpiece 50. This avoids the traditional positioning method of directly applying pressure with a pressure plate, effectively reducing the deformation of the motor housing workpiece 50 during the machining process and reducing the springback effect after unclamping, thereby improving the accuracy of the motor housing workpiece 50 after machining and making it meet the drawing requirements.

[0042] The method of using the pull-down centering machining fixture provided in this embodiment of the utility model is as follows: Connection between the positioning plate and the motor housing workpiece: Align the positioning plate with the motor housing workpiece, and use positioning pins to pass through the positioning holes on the positioning plate and the mounting holes on the end face of the motor housing workpiece in sequence to achieve circumferential positioning, ensuring that the connection holes correspond one-to-one with the mounting holes.

[0043] Rigid fastening: Use bolts to fix the connecting holes and mounting holes to ensure a stable connection between the positioning plate and the motor housing workpiece. Specifically, a torque wrench can be used to tighten multiple bolts in sequence with a torque of 8~10 N·m to ensure that the positioning plate and the end face of the motor housing workpiece are tightly fitted without gaps or looseness.

[0044] Overall clamping: Flip the connected "motor housing workpiece-positioning plate" assembly so that the positioning plate faces downward, and then hoist it into the machine tool chuck of the vertical lathe so that the annular conical surface of the positioning plate initially enters the clamping space of multiple jaws.

[0045] Automatic centering and clamping: The drive mechanism is activated, causing the jaws to tighten radially, with multiple sector-shaped and annular conical surfaces contacting each other. Utilizing the conical surface slope, the jaws apply a radial clamping force to the positioning plate, simultaneously decomposing this force into a radial component and an axial component of approximately 500-800N. This creates a downward pulling force while simultaneously clamping radially, causing the positioning plate to automatically move towards the positioning reference surface, achieving the dual effects of workpiece centering and axial clamping.

[0046] Machining execution: Start the machine tool and machine the inner cavity of the motor housing workpiece according to the preset program (such as boring, turning, etc.). During the machining process, the friction and pull-down force generated by the conical surface contact work together to resist the cutting force, preventing the motor housing workpiece from loosening or shifting.

[0047] The pull-down centering machining fixture provided in this embodiment of the utility model has at least the following advantages: (1) High-precision automatic centering: Multiple fan-shaped conical surfaces and annular conical surfaces are in contact with each other. By utilizing the pull-down effect generated by the inclination of the conical surfaces, the workpiece is automatically aligned with the center, with a centering accuracy of up to 0.01~0.03mm, which effectively solves the problem of insufficient positioning accuracy in the existing technology.

[0048] (2) Deformation-resistant design: The conical contact surface achieves surface contact, and the clamping force is evenly distributed along the circumference to avoid local stress concentration. It is especially suitable for thin-walled motor housings, and the deformation is controlled within 0.02mm. It effectively solves the problem in the prior art that excessive local pressure during rigid clamping causes elastic or plastic deformation of the thin-walled motor housing, affecting dimensional accuracy.

[0049] (3) Improved clamping stability: The pull-down force and the radial clamping force work together to form a rigid whole between the workpiece, the positioning plate and the machine tool chuck, effectively preventing the workpiece from shifting due to vibration or cutting force, reducing the risk of workpiece falling, reducing the scrap rate, and effectively solving the problem of poor clamping stability in the existing technology.

[0050] (4) Improve production efficiency: The modular pre-assembly design of the positioning plate and the motor housing workpiece reduces the clamping time by more than 50%, reduces the skill requirements of operators, adapts to automated production lines, and solves the problems of time-consuming manual adjustment and strong skill dependence in the existing technology.

[0051] (4) High versatility: By changing the positioning plate to match the connection holes of different models of motor housings, it can adapt to a variety of workpiece specifications and reduce the cost of jig procurement.

[0052] The above description is merely an embodiment of this utility model. It should be noted that those skilled in the art can make improvements without departing from the inventive concept of this utility model, but these improvements all fall within the protection scope of this utility model.

Claims

1. A pull-down centering machining fixture, characterized in that, include: Machine tool spindle; A machine tool chuck is mounted on the machine tool spindle. The machine tool chuck includes a chuck seat and a plurality of jaws disposed on the chuck seat. Each jaw includes a jaw body that is radially movable along the machine tool spindle and a jaw clamping part disposed on the jaw body. The inner sidewall of the jaw clamping part is provided with a fan-shaped conical surface that gradually expands from top to bottom with the axis of the machine tool spindle as the reference line. The positioning plate is used to fix the workpiece, and its outer peripheral wall is provided with an annular conical surface that gradually expands from top to bottom with the axis of the machine tool spindle as the reference line. The sector-shaped conical surface and the annular conical surface cooperate with each other to achieve the downward centering of the workpiece.

2. The pull-down centering machining fixture according to claim 1, characterized in that, The number of jaws is three, and the three jaws are distributed at equal angles along the circumference of the chuck seat.

3. The pull-down centering machining fixture according to claim 2, characterized in that, The sum of the actual contact areas between the annular conical surface and the three sector-shaped conical surfaces shall not be less than 90% of the area of ​​the annular conical surface.

4. The pull-down centering machining fixture according to claim 1, characterized in that, The fan-shaped cone surface has the same half-cone angle as the annular cone surface, and the half-cone angle is 2 to 5 degrees.

5. The pull-down centering machining fixture according to claim 4, characterized in that, The semi-cone angle is 3 degrees.

6. The pull-down centering machining fixture according to claim 1, characterized in that, It also includes a positioning reference surface, the lower end surface of which, when pulled down, engages with the positioning reference surface to define the axial reference position of the workpiece.

7. The pull-down centering machining fixture according to claim 6, characterized in that, The positioning reference surface is located at the lower end of the sector-shaped conical surface of the chuck clamping part.

8. The pull-down centering machining fixture according to claim 1, characterized in that, The chuck base is made of alloy steel.

9. The pull-down centering machining fixture according to claim 1, characterized in that, The chuck is made of 40CrNiMoA material with a hardness of 30~35HRC.

10. The pull-down centering machining fixture according to claim 1, characterized in that, The workpiece is a motor housing.

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