Positioning tool for grinding eccentric shaft and use mode

Abstract

The invention discloses a positioning tool for eccentric shaft grinding machining and a using mode, and belongs to the technical field of eccentric shaft grinding machining. The positioning tool comprises a base, a limiting block, a locking block, a first tightening screw and a second tightening screw. The base is provided with a positioning inner hole, a mounting hole and a center hole, the mounting hole and the positioning inner hole are vertically arranged and communicated, the positioning inner hole is in clearance fit with the maximum excircle of the eccentric shaft, and the center hole is used for eccentrically grinding the excircle in a centering manner; the limiting block and the locking block are symmetrically arranged in the mounting hole in a sliding mode, and the tail end of the limiting block is provided with a guide end capable of being embedded into the trapezoidal key groove. The first tightening screw and the second tightening screw are connected with the limiting block and the locking block to the base correspondingly and used for adjusting the pressing force of the limiting block and the pressing force of the locking block. The eccentric shaft machining device is used for solving the problems that in the prior art, operation is inconvenient, efficiency is low and cost is high, and efficient and accurate machining of an eccentric shaft is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of eccentric shaft grinding machining, and particularly to a positioning tooling and its usage method for eccentric shaft grinding machining. Background Art

[0002] In the field of modern mechanical manufacturing, eccentric shaft products are important mechanical parts and are widely used in various mechanical equipment. Conventional eccentric shafts usually have one or more eccentric segments, that is, their axis lines do not coincide with the rotation center line. This design enables the eccentric shaft to generate specific displacements or vibrations during rotation, thus meeting the special requirements of mechanical equipment for motion trajectories or power transmission. Therefore, the machining quality thereof is directly related to the operation accuracy and stability of the entire mechanical system. The machining of eccentric shafts involves multiple key processes, among which grinding machining is the key step to ensure its dimensional accuracy, shape accuracy, and surface quality. With the rapid development of industrial automation, higher requirements are put forward for the machining efficiency and accuracy of eccentric shaft parts.

[0003] For the grinding machining of eccentric shafts, the currently commonly used technical solution is to perform grinding treatment after eccentric outer circle positioning. In specific operations, a V-shaped limit block is usually used to align the position of the grinding outer circle, and then the product is clamped. After being fixed firmly, the V-shaped limit block is removed, and the grinding machining is started. This method can ensure the machining accuracy of the eccentric shaft to a certain extent, but many inconveniences and low efficiency problems are exposed in the actual operation process.

[0004] First of all, using a V-shaped limit block for alignment and clamping requires multiple adjustments and calibrations, and the operation process is cumbersome, increasing the machining preparation time. Secondly, the V-shaped limit block needs to be reinstalled and adjusted before each machining, which not only reduces the production efficiency but also may cause positioning errors due to human factors, affecting the machining quality. In addition, for eccentric shafts with special structures, although the method of eccentric outer circle alignment can ensure the position requirements, it is difficult to balance the dual requirements of machining efficiency and cost control. Especially when the demand for products is large, the limitations of the existing technology are more prominent.

[0005] Therefore, there is an urgent need for a more efficient and accurate machining positioning tooling to meet the high requirements for the machining of eccentric shaft parts in the field of modern mechanical manufacturing. Summary of the Invention

[0006] The present invention provides a positioning tooling and its usage method for eccentric shaft grinding machining, which can solve the problems of inconvenient operation, low efficiency, and high cost existing in the prior art, and realize the high-efficiency and accurate machining of eccentric shafts.

[0007] A positioning tool for eccentric shaft grinding, wherein the eccentric shaft comprises a normal grinding outer circle and an eccentric grinding outer circle, and the largest outer circle of the normal grinding outer circle has three equally divided trapezoidal keyways;

[0008] The positioning tooling comprises:

[0009] A base, wherein the base is provided with a positioning inner hole, a mounting hole and a center hole, wherein the mounting hole is vertically arranged and connected with the positioning inner hole, the positioning inner hole is matched with the maximum outer circle clearance of the eccentric shaft, and the center hole is used for centering and eccentric grinding of the outer circle;

[0010] A limit block and a locking block, wherein the limit block and the locking block are symmetrically slidably arranged in the mounting hole, and a guide end capable of being embedded in a trapezoidal keyway is provided at the end of the limit block;

[0011] Tightening screw one and tightening screw two, wherein tightening screw one and tightening screw two respectively connect the limit block and the locking block to the base, and are used to adjust the clamping force of the limit block and the locking block.

[0012] Furthermore, the cross section of the guide end is an isosceles trapezoidal structure, the guide angle at the top of the guide end is equal to the angle between the two side surfaces of the trapezoidal keyway, and the angle tolerance is controlled within the range of ±0.5°.

[0013] Furthermore, an arc-shaped positioning surface that matches the outer circle of the eccentric shaft is provided at the end of the locking block, and the tolerance between the curvature radius of the arc-shaped positioning surface and the maximum outer circle radius of the eccentric shaft is controlled within ±0.02mm.

[0014] Furthermore, the surface of the base is treated with soft nitriding, the thickness of the white bright layer is ≥0.015mm, and the surface hardness is ≥600HV.

[0015] Furthermore, the surface of the guide end is provided with a titanium nitride coating, and the coating thickness is 2-5 μm.

[0016] Furthermore, the arc-shaped positioning surface is provided with a grid-like anti-friction pattern with a depth of 0.1 mm.

[0017] Furthermore, the tightening screw one and the tightening screw two are both M16×1.5 hexagon socket screws, the tightening stroke of the tightening screw one and the tightening screw two is 5-10mm, and elastic gaskets are provided between the heads of the tightening screw one and the tightening screw two and the base.

[0018] Furthermore, the locking block and the limiting block are symmetrically distributed, a counterweight cavity is provided in the locking block, a counterweight block is fixed in the counterweight cavity by interference fit, and the mass of the counterweight block accounts for 20%-30% of the total mass of the locking block.

[0019] A method for using a positioning tool for the above-mentioned eccentric shaft grinding process comprises the following steps:

[0020] S1. Rotate the first screw counterclockwise to tighten it, so that the limit block retreats until the end of the guiding end protrudes from the inner wall of the positioning hole, and ensure that the eccentric shaft can smoothly slide into the positioning hole;

[0021] S2. Align the outer circle of the eccentric shaft ground normally with the positioning hole of the base, and rotate the eccentric shaft until its eccentrically ground outer circle is coaxial with the center hole;

[0022] S3. Install the eccentric shaft, and make the eccentric shaft slide into the positioning hole along the limit block until it abuts against the step surface;

[0023] S4. Rotate the first screw clockwise to tighten it, so that the guiding end presses against the trapezoidal keyway;

[0024] S5. Synchronously rotate and tighten the second screw, so that the arc-shaped positioning surface of the locking block fits the maximum outer circle of the eccentric shaft, and apply a symmetrical clamping force through the arc-shaped slider and play a counterweight role;

[0025] S6. Machine the eccentrically ground outer circle. After machining, first rotate the second screw counterclockwise to tighten it, and then rotate the first screw counterclockwise to tighten it, and take out the eccentric shaft.

[0026] Further, in step S1, the limit block retreats until the end of the guiding end is 0.2 - 0.5 mm away from the bottom plane of the trapezoidal keyway on the eccentric shaft.

[0027] The beneficial effects of the present invention are as follows:

[0028] 1. The present invention abandons the traditional V-shaped limit block limit, and uses the trapezoidal keyway structure carried by the eccentric shaft itself to design a limit block with the same angle as the trapezoidal groove for automatic alignment and positioning, eliminating the gap to the greatest extent, realizing the radial and axial double fixation of the eccentric shaft, effectively meeting the requirement of the positional tolerance of 0.1 mm between the trapezoidal keyway and each outer circle, and ensuring the precision and quality of the grinding process.

[0029] 2. Compared with the traditional normal eccentric tooling, the positioning tooling assembly of the present invention is reduced to three main parts: the base, the limit block, and the locking block. The structure is simpler. When clamping, the limit block does not need to be taken away, and the positioning and fixation can be directly completed, reducing the operation steps, saving the clamping time, and significantly improving the clamping efficiency.

[0030] 3. In the present invention, the limit block and the locking block are symmetrically slidably arranged in the installation holes of the base. The limit block positions and fixes the eccentric shaft, and the locking block can fix the maximum outer circle of the eccentric shaft. The symmetrical positioning on both sides ensures uniform force during the machining process, avoids the eccentricity of the eccentric shaft, and at the same time, the locking block plays a counterweight role, enhancing the stability of the tooling during the high-speed rotary grinding process, thus ensuring the machining quality. Description of the Drawings

[0031] Figure 1Schematic structural diagram of a positioning tooling for grinding an eccentric shaft provided by the present invention;

[0032] Figure 2 Cross-sectional view of a positioning tooling for grinding an eccentric shaft provided by the present invention;

[0033] Figure 3 Schematic structural diagram of an eccentric shaft applicable to the present invention;

[0034] Figure 4 Schematic structural diagram of a limit block, a locking block, a tightening screw I, a tightening screw II and an eccentric shaft provided by the present invention.

[0035] Explanation of reference numerals:

[0036] 1. Eccentric shaft; 2. Positioning tooling; 11. Normal grinding outer circle; 12. Eccentric grinding outer circle; 13. Trapezoidal keyway; 21. Base; 22. Limit block; 23. Locking block; 24. Tightening screw I; 25. Tightening screw II; 211. Positioning inner hole; 212. Mounting hole; 213. Center hole; 221. Guide end; 231. Arc-shaped positioning surface. Detailed implementation manners

[0037] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0038] A positioning tooling for grinding an eccentric shaft provided by an embodiment of the present invention, as Figure 2 shown, the positioning tooling 2 is applied to an eccentric shaft 1 with a special structure. The eccentric shaft 1 includes 3 normal grinding outer circles 11, the maximum outer circle diameter of which is φ12, the minimum outer circle diameter of which is φ6, and 1 eccentric grinding outer circle 12 with a diameter of φ6. Three equally spaced trapezoidal keyways 13 are provided at the maximum outer circle, and the positional tolerance between the trapezoidal keyways 13 and each grinding outer circle is 0.1 mm.

[0039] As Figure 1 、 Figure 3 and Figure 4 shown, the positioning tooling 2 includes:

[0040] Base 21: Select high-quality alloy steel material to make the base 21, and process a positioning inner hole 211, mounting holes 212 and a center hole 213 on the base 21. The diameter of the positioning inner hole 211 is designed according to the maximum outer diameter dimension of the eccentric shaft 1 to ensure clearance fit between the two; mounting holes 212 are symmetrically arranged on both sides of the positioning inner hole 211. The mounting holes 212 are perpendicular to and penetrate the positioning inner hole 211 for installing the limit block 22 and the locking block 23; the center hole 213 is machined with a standard center drill and is located at the center of both end faces of the base 21 for centering the eccentric grinding of the outer circle 12, ensuring that the eccentric grinding outer circle 12 of the eccentric shaft 1 is located exactly at the center of the axis. At the same time, it serves as a process reference when machining the base 21. Through the precise machining of the standard center drill, the manufacturing accuracy of the base 21 itself is ensured; the surface of the base 21 is subjected to soft nitriding treatment, the thickness of the white bright layer is ≥0.015 mm, and the surface hardness is ≥600 HV, which is wear-resistant. One eccentric tooling can process hundreds of thousands of products, and the deformation of the soft nitriding heat treatment is small, and the accuracy of the tooling after heat treatment can also be guaranteed, thus ensuring the machining accuracy of the products.

[0041] Limit block 22: The end of the limit block 22 is provided with a guiding end 221 that can be embedded in the trapezoidal keyway 13. The cross-section of the guiding end 221 is an isosceles trapezoid structure. The guiding angle at the top of the guiding end 221 is equal to the angle between the two side faces of the trapezoidal keyway 13, and the angular tolerance is controlled within the range of ±0.5°. The surface of the guiding end 221 is provided with a titanium nitride coating with a coating thickness of 2 - 5 μm. The limit block 22 is connected to the mounting hole 212 of the base 21 by tightening the first screw 24 and can slide in the mounting hole 212.

[0042] Locking block 23: The locking block 23 is symmetrically distributed with the limit block 22. The end of the locking block 23 is provided with an arc-shaped positioning surface 231 that coincides with the outer circle of the eccentric shaft 1. The tolerance of the radius of curvature of the arc-shaped positioning surface 231 and the maximum outer radius of the eccentric shaft 1 is controlled within ±0.02 mm. The arc-shaped positioning surface 231 is machined with grid-shaped anti-friction grooves with a depth of 0.1 mm to prevent the workpiece from moving and reduce friction; there is a counterweight cavity inside the locking block 23, and a counterweight block is fixed in the counterweight cavity by interference fit. The mass of the counterweight block accounts for 20% - 30% of the total mass of the locking block 23, and it is connected to the mounting hole 212 of the base 21 by tightening the second screw 25.

[0043] The first tightening screw 24 and the second tightening screw 25 connect the limit block 22 and the locking block 23 to the base 21 respectively for adjusting the pressing force between the limit block 22 and the locking block 23; both the first tightening screw 24 and the second tightening screw 25 are M16×1.5 hexagon socket head cap screws. The tightening stroke of the first tightening screw 24 and the second tightening screw 25 is 5 - 10 mm. Elastic washers are provided between the heads of the first tightening screw 24 and the second tightening screw 25 and the base 21 to prevent the screws from loosening and ensure the stability of the pressing force of the limit block 22 and the locking block 23.

[0044] A method for using a positioning tooling 2 for grinding an eccentric shaft 1 as described above, comprising the following steps:

[0045] Clamping preparation: Before clamping the eccentric shaft 1, rotate the first tightening screw 24 counterclockwise to retract the limit block 22 until the end of the guiding end 221 protrudes from the inner wall of the positioning inner hole 211 and is 0.2 - 0.5 mm away from the bottom plane of the trapezoidal keyway on the eccentric shaft 1. In this embodiment, rotating the first tightening screw 24 by a quarter turn causes the guiding end 221 to retract approximately 0.35 mm, which can be achieved by setting a scale ruler on the side of the base 21, ensuring that the eccentric shaft 1 can smoothly slide into the positioning inner hole 211 and the outermost end of the limit block 22 is within the outer circle of the trapezoidal keyway 13 of the eccentric shaft 1.

[0046] Coarse positioning: Align the normal grinding outer circle 11 of the eccentric shaft 1 with the positioning inner hole 211 of the base 21, insert the eccentric shaft 1, observe and ensure that the eccentric grinding outer circle 12 and the center hole 213 are on the same side, and rotate the eccentric shaft 1 until the eccentric grinding outer circle 12 and the center hole 213 are continuously approaching coaxiality. Since the outermost end of the limit block 22 is within the outer circle of the trapezoidal keyway 13 of the eccentric shaft 1, the eccentric shaft 1 will slide along the limit block 22 until it abuts against the step surface. There are three trapezoidal keyways 13 on the eccentric shaft 1, and the trapezoidal keyway 13 to be positioned can be roughly located by this method to ensure positioning accuracy.

[0047] Fine positioning and locking: After the eccentric shaft 1 is loaded, rotate the first tightening screw 24 clockwise to push the limit block 22 towards the trapezoidal keyway 13 of the eccentric shaft 1. Since the angles between the guiding end 221 of the limit block 22 and both sides of the trapezoidal keyway 13 are equal, the eccentric shaft 1 is automatically aligned to the exact middle position during the downward movement, ensuring that the eccentric outer circle of the eccentric shaft 1 is at the exact center of the axis. The equal angles between the guiding end 221 of the limit block 22 and both sides of the keyway can eliminate the clearance to the maximum extent and simultaneously achieve two-way fixation of the eccentric shaft 1 in the radial and axial directions. Synchronously rotate the second tightening screw 25 to make the arc-shaped positioning surface 231 of the locking block 23 closely fit the largest outer circle of the eccentric shaft 1, apply a symmetric clamping force through the arc-shaped slider, and utilize the counterweight function of the locking block 23 to ensure the stability of the eccentric tooling during high-speed rotary grinding.

[0048] Grinding process: After the clamping and fixing of the eccentric shaft 1 are completed, start the grinding equipment to process the eccentric grinding outer circle 12. During the processing, this tooling ensures the machining accuracy and quality with its stable positioning and clamping structure, effectively meeting the requirement of the positional tolerance of 0.1 between the trapezoidal keyway 13 and each outer circle.

[0049] Taking out the workpiece: After the eccentric outer circle grinding process is completed, first rotate the screw two 25 counterclockwise to tighten it, and then rotate the screw one 24 counterclockwise to tighten it. Loosen the limit block 22, and take out the eccentric shaft 1 from the positioning inner hole 211 of the base 21, completing the processing of one workpiece. Subsequently, repeat the above steps to process the next eccentric shaft 1.

[0050] The positioning tooling 2 provided by the present invention is provided with a limit block 22 that matches the trapezoidal keyway 13 of the product. The guiding end 221 of the limit block 22 has a special guiding angle equal to the angle of the trapezoidal keyway 13. During clamping, align the position of the trapezoidal keyway 13 of the product with the upper end of the positioning inner hole 211 of the base 21. After placing it, insert the limit block 22 into the positioning trapezoidal keyway 13. Since the guiding end 221 of the limit block 22 has equal angles with both sides of the trapezoidal keyway 13, the limit block 22 can automatically slide into the trapezoidal keyway 13 to align the eccentric outer circle position of the product, ensuring that the eccentric outer circle of the product is located at the exact center of the axis. By using the trapezoidal keyway 13 to determine the eccentric outer circle position, the relative position between the trapezoidal keyway 13 and the eccentric outer circle is ensured, thereby meeting the position tolerance requirement of 0.1. Moreover, the limit block 22 plays a role in positioning and fixing. Compared with the normal grinding tooling, after the product is positioned with this tooling, there is no need to remove the limit block 22, saving time and improving efficiency. The maximum outer circle is fixed by a locking block 23 with an arc-shaped positioning surface 231 on the opposite side of the limit block 22. Symmetrical positioning on both sides ensures uniform stress during the processing, avoiding displacement and ensuring the processing quality.

[0051] The above has described the embodiments of the present invention in detail, but the content is only the preferred embodiments of the present invention and cannot be considered as limiting the scope of implementation of the present invention. All equal changes and improvements made according to the scope of the application of the present invention should still fall within the scope covered by the patent of the present invention.

Claims

1. A positioning tooling for eccentric shaft grinding. The eccentric shaft (1) includes a normal grinding outer circle (11) and an eccentric grinding outer circle (12). There are 3 equally spaced trapezoidal keyways (13) at the largest outer circle of the normal grinding outer circle (11). It is characterized in that The positioning tooling (2) includes: A base (21). The base (21) is provided with a positioning inner hole (211), a mounting hole (212) and a center hole (213). The mounting hole (212) is perpendicular to and communicates with the positioning inner hole (211). The positioning inner hole (211) has a clearance fit with the largest outer circle of the eccentric shaft (1). The center hole (213) is used to center the eccentric grinding outer circle (12). A limit block (22) and a locking block (23). The limit block (22) and the locking block (23) are symmetrically and slidably arranged in the mounting hole (212). The end of the limit block (22) is provided with a guiding end (221) that can be embedded in the trapezoidal keyway (13). A tightening screw one (24) and a tightening screw two (25). The tightening screw one (24) and the tightening screw two (25) are respectively connected to the limit block (22) and the locking block (23) to the base (21) for adjusting the pressing force between the limit block (22) and the locking block (23).

2. The positioning tooling for eccentric shaft grinding as claimed in claim 1, wherein, The cross-section of the guiding end (221) is an isosceles trapezoid structure. The guiding angle at the top of the guiding end (221) is equal to the included angle of the two side faces of the trapezoidal keyway (13), and the angular tolerance is controlled within the range of ±0.5°.

3. A positioning tooling for eccentric shaft grinding as claimed in claim 1, characterized in that, The end of the locking block (23) is provided with an arc-shaped positioning surface (231) that fits the outer circle of the eccentric shaft (1). The curvature radius of the arc-shaped positioning surface (231) and the largest outer circle radius of the eccentric shaft (1) are controlled within ±0.02 mm.

4. A positioning tooling for eccentric shaft grinding as claimed in claim 1, wherein The surface of the base (21) is subjected to soft nitriding treatment, the thickness of the white bright layer is ≥0.015 mm, and the surface hardness is ≥600 HV.

5. The positioning tooling for eccentric shaft grinding machining according to claim 2, characterized in that, The surface of the guiding end (221) is provided with a titanium nitride coating, and the coating thickness is 2 - 5 μm.

6. The positioning tooling for eccentric shaft grinding as described in claim 3, characterized in that, The arc-shaped positioning surface (231) is provided with grid-shaped anti-friction grooves with a depth of 0.1 mm.

7. A positioning tooling for eccentric shaft grinding as claimed in claim 1, characterized in that, The tightening screw one (24) and the tightening screw two (25) are both M16×1.5 hexagon socket head cap screws. The tightening stroke of the tightening screw one (24) and the tightening screw two (25) is 5 - 10 mm. Elastic gaskets are provided between the heads of the tightening screw one (24) and the tightening screw two (25) and the base (21).

8. The positioning tooling for eccentric shaft grinding as claimed in claim 1, wherein The locking block (23) and the limit block (22) are symmetrically distributed. The locking block (23) is provided with a counterweight cavity, and a counterweight block is fixed in the counterweight cavity by interference fit. The mass of the counterweight block accounts for 20% - 30% of the total mass of the locking block (23).

9. A method for using the positioning tooling for eccentric shaft grinding according to any one of claims 1-8, characterized in that, It includes the following steps: S1. Rotate the tightening screw one (24) counterclockwise to retract the limit block (22) until the end of the guiding end (221) protrudes from the inner wall of the positioning inner hole (211), and ensure that the eccentric shaft (1) can smoothly slide into the positioning inner hole (211). S2. Align the normal grinding outer circle (11) of the eccentric shaft (1) with the positioning inner hole (211) of the base (21), and rotate the eccentric shaft (1) until its eccentric grinding outer circle (12) is coaxial with the center hole (213); S3. Insert the eccentric shaft (1), and slide the eccentric shaft (1) along the limit block (22) into the positioning inner hole (211) until it abuts against the step surface; S4. Rotate the first screw (24) clockwise to tighten it, so that the guiding end (221) presses against the trapezoidal keyway (13); S5. Synchronously rotate and tighten the second screw (25), so that the arc-shaped positioning surface (231) of the locking block (23) fits the maximum outer circle of the eccentric shaft (1), and apply a symmetrical clamping force through the arc-shaped slider and play a counterweight role; S6. Machine the eccentric grinding outer circle (12). After machining, first rotate the second screw (25) counterclockwise and then rotate the first screw (24) counterclockwise to take out the eccentric shaft (1).

10. The usage method according to claim 9, characterized in that, In step S1, the limit block (22) retracts until the end of the guiding end (221) is 0.2 - 0.5 mm from the bottom plane of the trapezoidal keyway (13) on the eccentric shaft (1).

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