An automated assembly method for arrays or multiple pin shaft and hole workpieces

Abstract

The application discloses an automatic assembly method for array or multiple pin shaft and hole workpieces, relates to the pin shaft assembly technical field, and uses the outer surface or some features of the workpiece to be assembled as a coarse reference, carries out floating preposition clamping on the workpiece, and then uses the features to be assembled as a fine reference to find the reference through a finding mechanism, realizes fine reference positioning, and carries out press fitting work on the clamped and fixed workpiece. The automatic assembly method for array or multiple pin shaft and hole workpieces is used, the shaft hole assembly precision is greatly improved, the fine positioning of the pin hole, the automatic feeding of the pin shaft and the automatic centering of the pin shaft and the hole are realized, and the accurate press fitting work of the pin shaft and the hole is realized.

Description

Technical Field

[0001] This invention relates to the field of pin assembly technology, and in particular to an automated assembly method for an array or multiple pins and hole workpieces. Background Technology

[0002] In mechanical assembly and production, interference fits are often used to ensure tight connection between components where high torque needs to be transmitted or where it is necessary to prevent the connection from coming loose. The principle of an interference fit is that the elasticity of the material enlarges and deforms the hole, allowing it to fit onto the shaft. When the hole returns to its original shape, it generates a clamping force on the shaft, thus connecting the two parts. Due to its simple structure, good neutrality, convenient torque transmission, and strong load-bearing capacity, interference fits are widely used in modern machining and production processes.

[0003] Interference fitting methods include cold fitting, hot fitting, and press fitting. In the field of automated assembly, press fitting is often used to meet the requirements of mass production and production line automation. However, in the automated press fitting process, if the connection performance cannot be quantitatively measured and precisely controlled, it usually leads to a deterioration in the quality of the hole-shaft interference fit. Due to problems such as the complex irregular shape of the workpiece structure and the lack of precise dimensional relationship between the pin hole and its outer surface, making it impossible to directly and accurately locate the pin hole through the outer surface, it is difficult to achieve automated assembly of shaft holes on irregularly shaped workpieces, which puts enormous pressure on the mass production of existing manufacturing enterprises.

[0004] According to CN107877154A, an automatic centering and pressing tool is disclosed. This tool divides the pressing rod into three sections, all of which are flexibly connected, allowing the pressing rod to automatically center under pressure. However, this invention is still an automated centering tool in the pressing process and does not achieve overall automation. According to CN118544099A, an automatic pressing device improves efficiency and yield by mechanically fixing the ball to be packaged and the process hole to designated positions before pressing. However, loading and unloading are done manually, making fully automated operation impossible.

[0005] In existing related technologies, shaft hole assembly is generally carried out by manual pressing. Since it is done manually, the work efficiency is low. At the same time, due to the different experience of the operators, the positioning accuracy of the shaft hole is poor when manually aligned. This can easily lead to excessive contact stress during shaft hole interference pressing, which can damage the parts or cause incomplete assembly. As a result, the pass rate of pressed products is uneven and the product consistency is poor. Summary of the Invention

[0006] The purpose of this invention is to provide an automated assembly method for arrays or multiple pins and holes in workpieces, solving the problems of low work efficiency and poor pin and hole positioning accuracy in existing assembly methods.

[0007] To achieve the above objectives, the present invention provides an automated assembly method for an array or multiple pins and holes in a workpiece, comprising the following steps:

[0008] S1. Place the workpiece to be assembled on the fixture, but do not clamp it. Use the pre-positioning tool on the fixture to pre-position the workpiece to be assembled.

[0009] S2. The workpiece to be assembled is sent to the assembly station of the pin hole to be assembled by the motion platform, so that the pin hole and the pressure head are on the same vertical line.

[0010] S3. Extend the pressure head and insert it into the pin hole. Use the pressure head to align the pin hole and determine its position.

[0011] S4. The clamping mechanism and the guide pressing mechanism press down to fix the position of the pin hole;

[0012] S5. The pressure head retracts, and the pin is sent to the front end of the sales mechanism through the pin feeding mechanism. The sales mechanism then sends the pin to the pin hole.

[0013] S6. Press down the pressure head to press the pin. After pressing, the pressure head retracts and the clamping mechanism and guide pressing mechanism are raised.

[0014] S7. Repeat steps S1-S6 until all holes are pressed in. Then, release the clamping mechanism and use the motion platform to send the workpiece to the unloading position to complete the unloading.

[0015] Preferably, the clamp is mounted on a motion platform, which is driven by a motor.

[0016] Preferably, the fixture includes a fixture body, a pre-positioning tool, and a clamping mechanism. The clamping mechanism is mounted on the fixture body, and the fixture body is connected to the pre-positioning tool, which pre-positions the workpiece to be assembled.

[0017] Preferably, the pressure head is located at the top of the guide clamping mechanism, and the size design of the pressure head should meet the following requirements:

[0018]

[0019] Wherein, d1 is the diameter of the cylindrical part of the pressure head; D0 is the diameter of the pin hole; Δδ is the floating range of the pin hole after pre-positioning; and ΔL is the cumulative positional tolerance of the multi-hole position.

[0020] Preferably, the front end of the guide pressing mechanism is configured as a trapezoidal structure, and the front end is provided with a through hole, which is concentric and coaxial with the pressing head.

[0021] Preferably, the feeding mechanism is located above the guiding and pressing mechanism, and a detector is installed at the front end of the feeding mechanism.

[0022] Preferably, the sales mechanism is mounted on the guide clamping structure, and is located below the pressure head and the sales delivery mechanism. The end of the sales delivery mechanism is coaxially mounted with the end of the sales mechanism.

[0023] Therefore, the present invention adopts the above-mentioned automated assembly method for arrays or multiple pins and holes, which transforms errors such as reference position and reference non-coincidence that exist in traditional assembly into matching errors between the alignment mechanism and the pin holes, greatly improving the assembly accuracy of shafts and holes. It solves the problem of shaft and hole assembly where there is no accurate dimensional relationship on the outer surface and it is impossible to directly and accurately position the holes to be assembled through the outer surface, greatly improving assembly accuracy and efficiency, and providing a new idea for the automation and intelligent transformation of enterprises.

[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the assembly structure of the present invention;

[0026] Figure 2 This is a schematic diagram of the final positioning method of the present invention;

[0027] Figure 3 This is a schematic diagram of the pin feeding and guiding method of the present invention;

[0028] Figure 4 for Figure 3 Enlarged view of the structure at point A in the middle;

[0029] Figure 5 This is a schematic diagram illustrating the self-aligning reference assembly technology route of the present invention;

[0030] Figure Labels

[0031] 1. Motion platform; 2. Fixture; 3. Guide clamping mechanism; 4. Push mechanism; 5. Pin delivery mechanism; 6. Clamping mechanism; 7. Pressure head; 8. Workpiece to be assembled; 9. Pin hole; 10. Pin shaft. Detailed Implementation

[0032] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0033] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0034] Example

[0035] Please see Figure 1-5 This invention provides an automated assembly method for workpieces with arrays or multiple pins and holes, comprising the following steps:

[0036] S1. Place the workpiece 8 to be assembled on the fixture 2, but do not clamp it. Use the pre-positioning tool on the fixture 2 to pre-position the workpiece 8 to be assembled.

[0037] S2. The workpiece 8 to be assembled is sent to the assembly station of the pin hole 9 to be assembled by the motion platform 1, so that the pin hole 9 and the pressure head 7 are roughly on the same vertical line.

[0038] S3. Extend the pressure head 7 and insert it into the pin hole 9, but not all the way in. Use the pressure head 7 to align the pin hole 9 and determine its position.

[0039] S4, clamping mechanism 6 and guide pressing mechanism 3 press down to fix the position of pin hole 9.

[0040] S5, the pressure head 7 retracts, and the pin shaft 10 is sent to the front end of the sales mechanism 4 through the pin feeding mechanism 5. The sales mechanism 4 then sends the pin shaft 10 to the pin hole 9.

[0041] S6. Press head 7 presses down to press pin 10. After pressing is completed, press head 7 retracts and clamping mechanism 6 and guide pressing mechanism 3 are raised.

[0042] S7. Repeat steps S1-S6 until all holes are pressed in. Then, the clamping mechanism 6 is released, and the workpiece is sent to the unloading position via the motion platform 1 to complete the unloading.

[0043] The motion platform 1 is used to move to different pressing stations when different pin holes 9 require pressing operations, in order to complete the subsequent final positioning and pressing operations. The pressing station is the position of the motion platform 1 when the pin hole 9 is below the pressing head. The motion platform 1 can be driven in various ways.

[0044] The fixture 2 is mounted on the motion platform 1. The fixture 2 includes a fixture body, a pre-positioning tool, and a clamping mechanism 6. The clamping mechanism 6 is mounted on the fixture body, which is connected to the pre-positioning tool. The pre-positioning tool pre-positions the workpiece to be assembled. The pre-positioning tool can be configured using various methods such as one-sided two-pin, locating pin, mandrel or conical center, or support pin. The purpose of the pre-positioning tool is to restrict the workpiece's degrees of freedom, allowing it to float only within a small range, thereby confirming the approximate position of the hole to be assembled. Different positioning errors can be calculated based on the positioning errors of different positioning methods. This positioning error is defined as Δδ, which is the floating range of the workpiece's pin hole after pre-positioning.

[0045] The pressure head 7 is located on the upper part of the guide clamping mechanism 3. By controlling the up-and-down movement of the pressure head 7, the workpiece is positioned and pressed. The pressure head 7 is mainly used for final positioning of the workpiece in its pre-positioned state and for subsequent pressing operations. For example... Figure 2 As shown, the final positioning and alignment process is as follows: The pressure head 7 is inserted into the pin hole 9 for alignment. At this time, the pressure head 7 can be considered a positioning pin. Utilizing the clearance fit between the pressure head 7 and the pin hole 9, the precise position of the pin hole 9 on the workpiece surface under the pre-positioned state is aligned, thus ensuring the precise positional relationship between the pin hole 9 and the pressure head 7. In order to ensure that the pressure head 7 can be smoothly inserted into the hole to complete the alignment during the final positioning and alignment process, the diameter of the cylindrical part of the pressure head 7 must be smaller than the minimum diameter of the pin hole 9, i.e., d1≤D. 0min .

[0046] During the final positioning and alignment process, the workpiece's alignable range depends on the guiding range of the pressure head, which is the difference in diameter between the cylindrical and chamfered portions of the pressure head 7. Furthermore, when pressing a single pin hole 9, to achieve smooth alignment, the floating range of the workpiece pin hole 9 should be less than the alignment range of the pressure head 7; otherwise, alignment cannot be achieved, i.e., d1-d2≥△δ. However, when pressing an array or multiple pin holes 9, it is necessary to consider not only the floating range of the workpiece pin holes 9 in the pre-positioned state but also the positional tolerances between the holes. Typically, the tolerance △L1 between a single pin hole 9 is only around 0.1 and can be ignored. However, when there are many holes to be assembled, the tolerances accumulate, totaling △L. Therefore, the alignment range of the pressure head 7 should be greater than the sum of the floating range of the workpiece pin holes and the cumulative positional tolerances of multiple holes, expressed as d1-d2≥△δ+△L.

[0047] In the subsequent pressing work, the lower part of the press head 7 needs to push the pin 10 to complete the pressing operation. If the contact surface is smaller, the pressure will be greater, and the requirements for the material and the overall structural strength of the pin 10 will be higher. Therefore, the area of ​​the lower surface d2 of the pin 10 should be increased as much as possible within the allowable range. Thus, d2 should satisfy d2≤d1-△δ-△L.

[0048] After final positioning, the only source of error is the fit clearance Δ' between the pressure head 7 and the pin hole 9. This fit clearance is the difference between the minimum diameter of the pin hole 9 and the diameter of the pressure head 7, i.e., Δ' = D. 0min -d1, if Δ' is smaller, it means the positioning error is smaller and the positioning is more accurate. Theoretically, Δ' can be infinitely close to 0, so d1 should satisfy d1≤D 0min .

[0049] The design of the pressure head should ensure that the diameter of its cylindrical portion is less than the minimum diameter of the pin hole 9, and d1 ≤ D. 0min The chamfered portion should satisfy d2≤d1-△δ-△L.

[0050] The guiding and clamping mechanism 3 and the clamping mechanism 6 work together to fix the workpiece after final positioning. In addition, the guiding and clamping mechanism 3 also guides the pin 10 during the press-fitting process. Figure 3 As shown, the front end of the guide clamping mechanism 3 is trapezoidal, and there is a through hole at the front end. The through hole is coaxial and concentric with the pressure head 7. During the final positioning process, the pressure head 7 passes through the through hole and is inserted into the pin hole 9 on the workpiece for alignment to complete the final positioning of the workpiece. At this time, the pressure head 7, the pin hole 9, and the through hole at the front end of the guide clamping mechanism 3 are concentric. After the final positioning is completed, the guide clamping mechanism 3 and the clamping mechanism 6 press down simultaneously to fix the workpiece. Then, the pressure head 7 is raised, and the pushing mechanism 4 pushes the pin shaft 10 forward, sending the pin shaft 10 to this through hole, so that the pin shaft 10, the pressure head 7, and the pin hole 9 are concentric, completing the guiding and feeding operation of the pin shaft 10. In order to meet the guiding and feeding function of the pin shaft 10, the diameter of the through hole should be slightly larger than the diameter of the pin shaft 10, but it should not be too large, otherwise the guiding function will be lost, that is, d3≥D1.

[0051] The pin feeding mechanism 5 is located above the guide pressing mechanism 3, and is arranged parallel to the pressing head 7. The pin feeding mechanism 5 is mainly used to feed the pin shaft 10 to the front end of the push-pull mechanism 4. The feeding method can be pneumatic, mechanical, or manual. The front end of the pin feeding mechanism 5 should be equipped with a detector, which can work with photoelectric sensors, magnetic sensors, or weight sensors to detect the feeding of the pin shaft 10, ensuring that the pin shaft 10 is fed to the push-pull mechanism 4. The push-pull mechanism 4 is installed on the guide pressing mechanism 3 and is used to push the pin shaft 10 conveyed by the pin feeding mechanism 5 to the through hole at the front end of the guide pressing mechanism 3. The pushing method can be a pneumatic cylinder, electric cylinder, or hydraulic cylinder, ensuring that its stroke is sufficient to push the pin shaft 10 to the front end of the guide pressing mechanism 3. The push-pull mechanism 4 and the pin feeding mechanism 5 together complete the pin feeding work in the pressing operation.

[0052] Therefore, the present invention adopts the above-mentioned automated assembly method for arrays or multiple pins and holes, which transforms errors such as reference position and reference non-coincidence that exist in traditional assembly into matching errors between the alignment mechanism and the pin holes, greatly improving the assembly accuracy of shafts and holes. It solves the problem of shaft and hole assembly where there is no accurate dimensional relationship on the outer surface and it is impossible to directly and accurately position the holes to be assembled through the outer surface, greatly improving assembly accuracy and efficiency, and providing a new idea for the automation and intelligent transformation of enterprises.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An automated assembly method for workpieces with arrays or multiple pins and holes, characterized in that, Includes the following steps: S1. Place the workpiece to be assembled on the fixture, but do not clamp it. Use the pre-positioning tool on the fixture to pre-position the workpiece to be assembled. S2. The workpiece to be assembled is sent to the assembly station of the pin hole to be assembled by the motion platform, so that the pin hole and the pressure head are on the same vertical line. S3. Extend the pressure head and insert it into the pin hole. Use the pressure head to align the pin hole and determine its position. S4. The clamping mechanism and the guide pressing mechanism press down to fix the position of the pin hole; S5. The pressure head retracts, and the pin is sent to the front end of the sales mechanism through the pin feeding mechanism. The sales mechanism then sends the pin to the pin hole. S6. Press down the pressure head to press the pin. After pressing, the pressure head retracts and the clamping mechanism and guide pressing mechanism are raised. S7. Repeat steps S1-S6 until all holes are pressed in. Then, release the clamping mechanism and use the motion platform to send the workpiece to the unloading position to complete the unloading.

2. The automated assembly method for an array or multiple pins and holes workpiece according to claim 1, characterized in that: The fixture is mounted on a motion platform, which is driven by a motor.

3. The automated assembly method for an array or multiple pins and holes of a workpiece according to claim 2, characterized in that: The fixture includes a fixture body, a pre-positioning tool, and a clamping mechanism. The clamping mechanism is mounted on the fixture body, which is connected to the pre-positioning tool. The pre-positioning tool pre-positions the workpiece to be assembled.

4. An automated assembly method for an array or multiple pins and holes in a workpiece according to claim 3, characterized in that: The pressure head is located at the top of the guide clamping mechanism, and the size design of the pressure head should meet the following requirements: Wherein, d1 is the diameter of the cylindrical part of the pressure head; d2 is the diameter of the chamfered part of the pressure head; D0 is the diameter of the pin hole; Δδ is the floating range of the pin hole after pre-positioning; and ΔL is the cumulative positional tolerance of the multi-hole position.

5. The automated assembly method for an array or multiple pins and holes of a workpiece according to claim 4, characterized in that: The front end of the guide clamping mechanism is set as a trapezoidal structure, and a through hole is provided at the front end. The through hole is concentric and coaxial with the pressure head.

6. The automated assembly method for an array or multiple pins and holes workpiece according to claim 5, characterized in that: The feeding mechanism is located above the guiding and pressing mechanism, and a detector is installed at the front end of the feeding mechanism.

7. An automated assembly method for an array or multiple pins and holes workpiece according to claim 6, characterized in that: The sales mechanism is mounted on the guide clamping structure and is located below the pressure head and the sales delivery mechanism. The end of the sales delivery mechanism is coaxially mounted with the end of the sales mechanism.

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