Positioning pin, positioning method and mechanical part clamping process

Abstract

The invention belongs to the technical field of machining, and particularly relates to a positioning pin, a positioning method and a mechanical part clamping process, the sectional structural design of bolt connection is adopted, a replaceable outer mold is arranged to adapt to positioning holes of different sizes, the stability of a machining standard is ensured by eliminating the freedom degree in six directions, and the machining precision is improved. A mechanical part machining object is divided into a stable clamping area and a dynamic clamping area, in the dynamic clamping area, the freedom degrees of the mechanical part machining object in six directions are limited through adsorption type positioning, and a plurality of floating clamping points and auxiliary supporting points are arranged in the stable clamping area to support parts. In the machining process, the machining object of the mechanical part is clamped through the floating clamping point so as to determine the position of the clamping point; while precise positioning of the workpiece is achieved, deformation in the machining process is effectively reduced, and the production efficiency of part machining is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical processing, and in particular relates to a positioning pin, a positioning method and a mechanical parts clamping process. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] During the parts processing, floating clamping technology is an advanced method in the field of mechanical processing to solve the problem of workpiece deformation during processing; it is particularly suitable for the processing of large or thin-walled parts, but the parts are prone to deformation during processing. Through one or more floating clamping modules, the clamping force can be dynamically adjusted according to the actual deformation of the workpiece, which can effectively avoid the deformation accumulation problem caused by rigid clamping and alleviate the deformation problem to a certain extent. However, due to the premise of fixed clamping, its effect on solving the deformation problem caused by the release of residual stress is limited.

[0004] As a classic machining positioning method, the one-side two-pin positioning method has been widely used in the fixture positioning of shell and cover parts. Two different types of pins (i.e. cylindrical pins and diamond pins) are used to jointly determine the precise position of the workpiece. Among them, the center distance between the cylindrical pin and the diamond pin and their matching accuracy with the workpiece positioning hole are the key factors to ensure the positioning accuracy. In traditional machining practice, the one-side two-pin positioning device is often fixed. Once the position of the pin is determined, it is difficult to adjust it. It is only suitable for mass production of a single product, but it is not flexible and adaptable enough when facing the production needs of diversified products and smaller batches. Summary of the invention

[0005] In order to solve the above problems, the present invention proposes a locating pin, a positioning method and a mechanical parts clamping process, adopts a segmented structural design with bolt connections, and provides a replaceable external mold to adapt to locating holes of different sizes. It simplifies the disassembly and assembly of the locating pin while extending its service life. The stability of the machining datum is ensured by eliminating the degrees of freedom in six directions. While achieving precise positioning of the workpiece, it effectively reduces deformation in the machining process and improves the production efficiency of parts machining.

[0006] According to some embodiments, a first solution of the present invention provides a positioning pin, which adopts the following technical solution:

[0007] A positioning pin comprises an inner mold, an outer mold, and a guide plate and a connecting bolt for connecting the inner mold and the outer mold; an inner mold return spring and an outer mold return spring are respectively provided in the inner mold and the outer mold; the inner mold and the outer mold are movably connected to each other, and the size of the outer mold is controlled by the movement of the inner mold to achieve positioning of apertures of different sizes; the guide plate is used to limit the movement path of the inner mold, and the inner mold return spring is provided between the guide plate and the inner mold, and the inner mold return spring supports the guide plate and the outer mold when the inner mold retreats, so that the outer mold does not move in a direction perpendicular to the workpiece.

[0008] As a further technical limitation, the outer mold reset spring wraps the outer mold in a ring shape. When the inner mold retreats, a gap is generated between the outer mold and the inner mold. The outer mold reset spring tightens and resets the outer mold based on elastic potential energy.

[0009] As a further technical limitation, when the inner mold is pushed upward along the guide plate to open the outer mold, the size of the outer mold becomes larger; when the inner mold is moved downward, the outer mold return spring is tightened to reduce the size of the outer mold.

[0010] According to some embodiments, the second solution of the present invention provides a positioning method, using the positioning pin provided by the first solution, and adopting the following technical solution:

[0011] A positioning method divides a mechanical part processing object into a stable clamping area and a dynamic clamping area. In the dynamic clamping area, adsorption positioning is used to limit the freedom of the mechanical part processing object in six directions. In the stable clamping area, a number of floating clamping points and auxiliary support points are set to support the parts. During the processing, the mechanical part processing object is clamped by the floating clamping points to determine the clamping point position.

[0012] As a further technical limitation, the contour center position of the mechanical part processing object is selected as the stable clamping area according to the characteristics of the mechanical part processing object; the centroid-geometric distribution method is used to distribute and calculate the mass and the end point position, and the centroid of each mechanical processing object is obtained. The stable clamping area is determined where the centroid is densely distributed. The active clamping point and the pin positioning point are determined to determine the stable clamping area, and adsorption-type positioning elements are used at the active positioning points to limit the six degrees of freedom of the part.

[0013] Furthermore, the centroid coordinates (Xc, Yc) of the machined object are Among them, x i ,y i is the centroid coordinate of sub-region i, A iis the area of ​​the sub-region; if the thin-walled part of the mechanical part processing object contains holes or openings, the area of ​​the thin-walled part is deducted, and the centroid is recalculated based on the remaining part to ensure that the centroid position is within the actual range of the thin-walled part.

[0014] As a further technical limitation, the support area is divided according to the centroid position and the geometric shape of the thin-walled part, and the rigid area near the centroid or at the edge of the workpiece is determined; the clamping point is determined based on modal analysis.

[0015] According to some embodiments, a third solution of the present invention provides a mechanical parts clamping process using the positioning pin provided by the first solution or the positioning method provided by the second solution, using the following technical solutions:

[0016] A mechanical parts clamping process, comprising:

[0017] According to the geometric characteristics of the mechanical parts processing object, the contour center of the mechanical parts processing object is selected as the fixed clamping point;

[0018] Combined with finite element analysis, the active clamping points and the locating pin positions are determined to determine the stable clamping area;

[0019] According to the position of the stable clamping area and the shape and contour of the mechanical parts processing object, the position and number of the floating clamping points and auxiliary support points are determined, and the dynamic clamping area is determined;

[0020] The mechanical part processing object is clamped according to the determined stable clamping area and dynamic clamping area. When the mechanical part processing object is deformed to a relative deformation threshold, the floating fixture releases the clamping to release the processing deformation in the dynamic clamping area. After the release is completed, the mechanical part processing object is re-clamped until the processing is completed.

[0021] As a further technical limitation, the number of clamping points, the position of the contour machining boss of the mechanical part machining object and the position of the floating clamping point are determined according to the size and structural complexity of the mechanical part machining object, and the dynamic clamping area is determined.

[0022] As a further technical limitation, based on modal analysis, it is verified whether the selected clamping point can reduce the vibration amplitude under low-order modes, identify the dangerous area of ​​the mechanical part processing object with the largest amplitude in vibration, and determine the key points of insufficient stiffness of the mechanical part processing object;

[0023] Auxiliary support blocks are added to the identified dangerous area with the largest amplitude to enhance the clamping rigidity and reduce the impact of vibration on machining accuracy; repeated identification, continuous monitoring and adjustment are performed until the rigidity meets the machining requirements.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention adopts a segmented structural design connected by bolts and provides a replaceable outer mold to adapt to positioning holes of different sizes. It simplifies the disassembly and assembly of the positioning pins and prolongs the service life. It ensures the stability of the processing reference by eliminating the degrees of freedom in six directions. While achieving precise positioning of the workpiece, it effectively reduces the deformation of the processing process and improves the production efficiency of parts processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings in the specification that constitute a part of this embodiment are used to provide a further understanding of this embodiment. The schematic embodiments of this embodiment and their descriptions are used to explain this embodiment and do not constitute improper limitations on this embodiment.

[0027] Figure 1 A schematic diagram of the structure of a positioning pin in the first embodiment of the present invention;

[0028] Figure 2 A schematic diagram of a positioning method in Embodiment 2 of the present invention;

[0029] Figure 3 This is a schematic diagram of a mechanical parts clamping process in Embodiment 3 of the present invention;

[0030] Among them, 101, outer mold; 102, outer mold reset spring; 103, inner mold reset spring; 104, inner mold; 105, guide plate; 201, floating clamp; 202, auxiliary support clamp; 203, positioning pin; 204, fixed clamping point; 205, stable clamping area; 206, adsorption-type positioning element. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0032] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0033] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0034] In the present invention, terms such as "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "side", "bottom", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are relational words determined only for the convenience of describing the structural relationships of the various parts or elements of the present invention, and do not specifically refer to any part or element in the present invention and should not be understood as limitations on the present invention.

[0035] In the present invention, terms such as "fixed connection", "connected", "connection", etc. should be understood in a broad sense, indicating that it can be fixedly connected, integrally connected or detachably connected; it can be directly connected or indirectly connected through an intermediate medium. For relevant scientific research or technical personnel in this field, the specific meanings of the above terms in the present invention can be determined according to specific circumstances, and they cannot be understood as limitations on the present invention.

[0036] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0037] Embodiment 1

[0038] Embodiment 1 of the present invention introduces a positioning pin.

[0039] A positioning pin comprises an inner mold, an outer mold, and a guide plate and a connecting bolt for connecting the inner mold and the outer mold; an inner mold return spring and an outer mold return spring are respectively provided in the inner mold and the outer mold; the inner mold and the outer mold are movably connected to each other, and the size of the outer mold is controlled by the movement of the inner mold to achieve positioning of apertures of different sizes; the guide plate is used to limit the movement path of the inner mold, and the inner mold return spring is provided between the guide plate and the inner mold, and the inner mold return spring supports the guide plate and the outer mold when the inner mold retreats, so that the outer mold does not move in a direction perpendicular to the workpiece.

[0040] The outer mold reset spring wraps the outer mold in a ring shape. When the inner mold retreats, a gap is generated between the outer mold and the inner mold. The outer mold reset spring tightens and resets the outer mold based on elastic potential energy. When the inner mold pushes the outer mold upward along the guide plate, the size of the outer mold becomes larger. When the inner mold moves downward, the outer mold reset spring tightens to reduce the size of the outer mold.

[0041] like Figure 1A positioning pin shown in the figure comprises an outer mold 101, an outer mold return spring 102, an inner mold return spring 103, an inner mold 104 and a guide plate 105. Compared with conventional positioning pins, the positioning pins in this embodiment are connected by bolts, and the outer mold 101 can be replaced as needed to adapt to positioning holes of different sizes to adapt to the positioning of different sizes of apertures of workpieces; the size of the outer mold is controlled by the movement of the inner mold 104. When the inner mold 104 is upward, the outer mold is stretched along the guide plate 105 to increase the size of the outer mold 101. When the inner mold 101 is downward, the inner mold return spring 103 is tightened to reduce the size of the outer mold 101, thereby achieving the effect of convenient disassembly and assembly and reducing the wear of the positioning pin.

[0042] The positioning pin in this embodiment simplifies the assembly and disassembly process, prolongs the service life of the positioning pin, expands its application range, and significantly improves work efficiency.

[0043] Embodiment 2

[0044] The second embodiment of the present invention introduces a positioning method, which adopts the positioning pin introduced in the first embodiment.

[0045] A positioning method divides a mechanical part processing object into a stable clamping area and a dynamic clamping area. In the dynamic clamping area, adsorption positioning is used to limit the freedom of the mechanical part processing object in six directions. In the stable clamping area, a number of floating clamping points and auxiliary support points are set to support the parts. During the processing, the mechanical part processing object is clamped by the floating clamping points to determine the clamping point position.

[0046] The positioning method used in this embodiment is the 1-2-2+X positioning method. Figure 2 As shown, 201 is a floating fixture, 202 is an auxiliary support fixture, 203 is a positioning pin, 204 is a fixed clamping point, 205 is a stable clamping area, and 206 is an adsorption-type positioning element. This embodiment adopts a positioning device composed of 1 fixed clamping fixture, 2 adsorption-type positioning elements, 2 positioning pins and X floating clamps; wherein, 1 fixed clamping fixture fixes 3 degrees of freedom of the workpiece, two adsorption-type positioning elements fix 2 degrees of freedom of the workpiece, and 2 positioning pins fix 1 degree of freedom of the workpiece. The core of the positioning technology lies in the fine regional division of the processing object, which is divided into a stable clamping area and a dynamic clamping area. The function of the stable clamping area is to limit the six degrees of freedom of the part through adsorption-type positioning elements, fixed clamping fixtures and positioning pins to ensure the invariance of the processing reference. Relatively speaking, the rest of the part is divided into a dynamic clamping area, giving it greater flexibility to adapt to various deformations that may occur during the processing process.

[0047] According to the characteristics of the mechanical parts processing object, the contour center position of the mechanical parts processing object is selected as the stable clamping area; the centroid-geometric distribution method is used to distribute and calculate the mass and the end point position to obtain the centroid of each mechanical processing object. The densely distributed centroids are the stable clamping area, and the active clamping points and pin positioning points are determined to determine the stable clamping area. Adsorption-type positioning elements are used at the active positioning points to limit the six degrees of freedom of the parts.

[0048] The centroid coordinates (Xc, Yc) of the machining object are: Among them, x i ,y i is the centroid coordinate of sub-region i, A i is the area of ​​the sub-region; if the thin-walled part of the mechanical part processing object contains holes or openings, the area of ​​the thin-walled part is deducted, and the centroid is recalculated based on the remaining part to ensure that the centroid position is within the actual range of the thin-walled part.

[0049] like Figure 3 As shown in the figure, during the workpiece removal process, if the thin-walled part contains holes or openings, the area of ​​these parts needs to be deducted and the centroid needs to be recalculated based on the remaining parts; ensure that the centroid position is within the actual range of the thin-walled part. According to the centroid position and the geometric shape of the thin-walled part, the support area is divided; these support areas are usually rigid areas near the centroid or at the edge of the workpiece. According to the experience of modal analysis, the rib area and the edge area are usually parts with better rigidity and can be given priority as clamping points. Use active clamping points and locating pins to surround the calculated centroid as much as possible and a smaller surrounding area on the part to determine the active clamping points and locating pin positions.

[0050] According to the centroid position and the geometric shape of the thin-walled part, the support area is divided and the rigid area near the centroid or the edge of the workpiece is determined; the clamping point is determined based on modal analysis.

[0051] The detailed steps are the same as the working principle of the positioning pin provided in Example 1, and will not be repeated here.

[0052] Embodiment 3

[0053] Embodiment 3 of the present invention provides a mechanical parts clamping process, which adopts the positioning pin introduced in embodiment 1 or the positioning method introduced in embodiment 2.

[0054] A mechanical parts clamping process, in which the contour center of the mechanical parts processing object is selected as a fixed clamping point according to the geometric characteristics of the mechanical parts processing object;

[0055] Combined with finite element analysis, the active clamping points and the locating pin positions are determined to determine the stable clamping area;

[0056] According to the position of the stable clamping area and the shape and contour of the mechanical parts processing object, the position and number of the floating clamping points and auxiliary support points are determined, and the dynamic clamping area is determined;

[0057] The mechanical part processing object is clamped according to the determined stable clamping area and dynamic clamping area. When the mechanical part processing object is deformed to a relative deformation threshold, the floating fixture releases the clamping to release the processing deformation in the dynamic clamping area. After the release is completed, the mechanical part processing object is re-clamped until the processing is completed.

[0058] As one or more implementation modes, the number of clamping points, the position of the contour machining boss of the mechanical part machining object and the position of the floating clamping point are determined according to the size and structural complexity of the mechanical part machining object, and the dynamic clamping area is determined.

[0059] As one or more implementation methods, verify whether the selected clamping point can reduce the vibration amplitude under the low-order mode based on modal analysis, identify the dangerous area of ​​the mechanical part processing object with the largest amplitude in vibration, and determine the key point of insufficient stiffness of the mechanical part processing object;

[0060] Auxiliary support blocks are added to the identified dangerous area with the largest amplitude to enhance the clamping rigidity and reduce the impact of vibration on machining accuracy; repeated identification, continuous monitoring and adjustment are performed until the rigidity meets the machining requirements.

[0061] In this embodiment, sensors are installed on the fixtures so that these devices can adjust the clamping action in the upper computer according to the deformation of the workpiece during processing. When the processing deformation exceeds the deformation threshold, the threshold is obtained by the relative deformation, the floating fixture is loosened, the clamping is released, and the deformation is effectively alleviated to ensure the processing accuracy. After release, the clamp is re-clamped. For areas with large workpiece vibration, auxiliary support blocks for enhancing the clamping rigidity are added in the identified dangerous areas with the largest amplitude to reduce the impact of vibration on processing accuracy; repeat identification and continuous monitoring and adjustment until the rigidity meets the processing requirements.

[0062] The above description is only a preferred embodiment of the present embodiment and is not intended to limit the present embodiment. For those skilled in the art, the present embodiment may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present embodiment shall be included in the protection scope of the present embodiment.

Claims

1. A positioning pin, characterized in that: It includes an inner mold, an outer mold, and a guide plate and connecting bolts for connecting the inner mold and the outer mold; the inner mold and the outer mold are respectively provided with an inner mold return spring and an outer mold return spring; the inner mold and the outer mold are movably connected, and the size of the outer mold is controlled by the movement of the inner mold to achieve positioning of apertures of different sizes; the guide plate is used to limit the movement path of the inner mold, and the inner mold return spring is arranged between the guide plate and the inner mold. The inner mold return spring supports the guide plate and the outer mold when the inner mold retreats, so that the outer mold does not move in a direction perpendicular to the workpiece.

2. A positioning pin as claimed in claim 1, characterized in that: The outer mold return spring wraps the outer mold in a ring shape. When the inner mold retreats, a gap is generated between the outer mold and the inner mold. The outer mold return spring tightens and returns the outer mold based on elastic potential energy.

3. A positioning pin as claimed in claim 1, characterized in that: When the inner mold is pushed upward along the guide plate to open the outer mold, the size of the outer mold becomes larger; when the inner mold is moved downward, the outer mold return spring is tightened, so that the size of the outer mold is reduced.

4. A positioning method, using the positioning pin according to any one of claims 1 to 3, characterized in that: The mechanical parts processing object is divided into a stable clamping area and a dynamic clamping area. In the dynamic clamping area, adsorption positioning is used to limit the freedom of the mechanical parts processing object in six directions. Several floating clamping points and auxiliary support points are set in the stable clamping area to support the parts. During the processing, the mechanical parts processing object is clamped by the floating clamping points to determine the clamping point position.

5. A positioning method as claimed in claim 4, characterized in that: According to the characteristics of the mechanical parts processing object, the contour center position of the mechanical parts processing object is selected as the stable clamping area; the centroid-geometric distribution method is used to distribute and calculate the mass and the end point position to obtain the centroid of each mechanical processing object. The densely distributed centroids are the stable clamping area, and the active clamping points and pin positioning points are determined to determine the stable clamping area. Adsorption-type positioning elements are used at the active positioning points to limit the six degrees of freedom of the parts.

6. A positioning method as claimed in claim 5, characterized in that: The centroid coordinates (Xc, Yc) of the machining object are: Among them, x i ,y i is the centroid coordinate of sub-region i, A i is the area of ​​the sub-region; if the thin-walled part of the mechanical part processing object contains holes or openings, the area of ​​the thin-walled part is deducted, and the centroid is recalculated based on the remaining part to ensure that the centroid position is within the actual range of the thin-walled part.

7. A positioning method as claimed in claim 4, characterized in that: According to the centroid position and the geometric shape of the thin-walled part, the support area is divided and the rigid area near the centroid or the edge of the workpiece is determined; the clamping point is determined based on modal analysis.

8. A mechanical parts clamping process, using the positioning pin as described in any one of claims 1 to 3 or the positioning method as described in any one of claims 4 to 7, characterized in that: include: According to the geometric characteristics of the mechanical parts processing object, the contour center of the mechanical parts processing object is selected as the fixed clamping point; Combined with finite element analysis, the active clamping points and the locating pin positions are determined to determine the stable clamping area; According to the position of the stable clamping area and the shape and contour of the mechanical parts processing object, the position and number of the floating clamping points and auxiliary support points are determined, and the dynamic clamping area is determined; The mechanical part processing object is clamped according to the determined stable clamping area and dynamic clamping area. When the mechanical part processing object is deformed to a relative deformation threshold, the floating fixture releases the clamping to release the processing deformation in the dynamic clamping area. After the release is completed, the mechanical part processing object is re-clamped until the processing is completed.

9. A mechanical parts clamping process as claimed in claim 8, characterized in that: According to the size and structural complexity of the mechanical parts processing object, the number of clamping points, the position of the contour processing boss of the mechanical parts processing object and the position of the floating clamping point are determined to complete the determination of the dynamic clamping area.

10. A mechanical parts clamping process as claimed in claim 8, characterized in that: Based on modal analysis, verify whether the selected clamping point can reduce the vibration amplitude under low-order modes, identify the dangerous area of ​​the mechanical part processing object with the largest amplitude in vibration, and determine the key points of insufficient stiffness of the mechanical part processing object; Auxiliary support blocks are added to the identified dangerous area with the largest amplitude to enhance the clamping rigidity and reduce the impact of vibration on machining accuracy; repeated identification, continuous monitoring and adjustment are performed until the rigidity meets the machining requirements.

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