Double-mistake-proofing clamp positioning mechanism

Abstract

The utility model discloses a double mistake-proofing clamp positioning mechanism, which comprises a positioning part and a gas detection part, the positioning part comprises three supporting blocks, each supporting block is provided with a convex step, the top surface of each convex step is used as a supporting surface, two supporting blocks are respectively provided with a spring taper pin, the gas detection part comprises gas detection ports arranged on each supporting surface, and the gas detection ports are respectively provided with a spring taper pin. The spring taper pin is provided with a lower stroke limiting structure, and when the lower stroke limiting structure limits that the spring taper pin is not accurately inserted into a positioning hole in a workpiece, the spring taper pin is pressed by a positioning surface on the workpiece downwards to a limiting limit position and then supports the workpiece, so that a supporting surface is not attached to the positioning surface, the gas detection opening is exposed, and first mistake proofing is achieved; the gas detection ports are close to the edge of the supporting surface where the gas detection ports are located, and the positions of the three gas detection ports are associated, so that one gas detection port must be exposed when the workpiece is installed obliquely, and secondary mistake proofing is achieved; the device has the advantages that the possibility of misjudgment of mistake-proof gas detection is effectively reduced by arranging a lower stroke limiting structure of the spring taper pin and optimizing the positions of the three gas detection ports.

Description

Technical Field

[0001] This utility model belongs to the field of machining, and relates to a machining fixture, and more particularly to a double error-proof fixture positioning mechanism. Background Technology

[0002] In modern machining, machining fixtures serve as crucial tools for workpiece positioning and clamping. Their performance directly impacts the accuracy and stability of workpiece machining. Machining fixtures comprise positioning mechanisms and clamping mechanisms. A vital auxiliary function of the positioning mechanism is error prevention, primarily aimed at preventing incorrect workpiece position and orientation within the fixture. This assists workers in accurately loading the workpiece and avoids machining errors or collisions.

[0003] Existing positioning mechanisms generally include a support block with an upward-protruding step. The top surface of the step serves as the support surface. The positioning error-proofing measure is pneumatic detection of the support surface, such as... Figure 1 As shown, a gas detection port (generally D0.5 to D1.2) is provided on the support surface. The gas detection port is connected to the internal air supply system a3 of the machine tool through the gas detection channel a2 located in the support block a1. The air supply system a3 includes an air sensor a31, a pressure gauge a32, a pressure regulating valve a33, an air filter a34, and an air source a35. The gas provided by the air source a35 passes through the air filter a34, then through the pressure regulating valve a33 and the air sensor a31 before entering the gas detection channel a2. The pressure gauge a32 is located on the connecting pipe between the pressure regulating valve a33 and the air sensor a31. The air supply system a3 provides stable and clean gas, and the air sensor a31 monitors the gas detection value (air leakage or air pressure value). When there is no workpiece, the air leakage (air detection value) of the air detection port is stable. When the positioning surface on the workpiece is in contact with the support surface in the positioning mechanism, the air detection port is covered by the positioning surface, and the air leakage will decrease. When the air detection value is within the preset standard value, it is considered qualified. That is, the air detection value is used to judge whether the workpiece positioning is accurate. When the positioning surface is a machined surface, the air detection value is usually stable and basically zero. When the positioning surface is a cast blank surface, due to the unevenness of the surface, the air detection port cannot be completely covered, and the height difference deviation of the cast blank surface on different workpieces is unstable, which makes the air detection value between different workpieces fluctuate greatly. Therefore, the preset standard value is usually set very large. However, an excessively large preset standard value can easily cause misjudgment, judging inaccurate positioning as qualified, thereby causing machining accidents.

[0004] In the positioning mechanism of the OP10 model fixture for positioning the cast blank surface, a positioning method with two pins on one side is often used, i.e.: see [link to relevant documentation] Figure 2 The positioning on workpiece b1 uses three blank positioning surfaces Z1, Z2, and Z3, one blank conical hole X, and one blank oblong hole Y; the positioning in the OP10 model fixture corresponds to three support surfaces and two spring tapered pins. Figure 3This diagram shows the first blank positioning surface Z1 in contact with the first support surface b2 and the first spring tapered pin b3 inserted into the blank's conical hole X. Figure 4 The diagram shows the second blank positioning surface Z2 in contact with the second support surface b4 and the second spring tapered pin b5 inserted into the blank's oblong hole Y. Figure 5 A schematic diagram showing the contact between the third blank positioning surface Z3 and the third support surface b6 is shown. Figure 3 and Figure 4 In the middle, the spring tapered pin is always pushed up by the spring b7, so that the tapered surface of the spring tapered pin is always in contact with the positioning hole (i.e. the blank conical hole X or the blank waist-shaped hole Y) on the workpiece b1 to achieve the positioning function, and the air inspection port b8 is covered by the blank positioning surface.

[0005] In the OP10 model fixture, the workpiece clamping process is as follows: a worker or robot places the workpiece onto the fixture, aligns the positioning holes and spring taper pins, and initially fits the blank positioning surface and the support surface together. Figure 3 and Figure 4 As shown; then the equipment starts, and the hydraulic cylinders on the fixture clamp in sequence, positioning and clamping the workpiece. However, there is a problem here: the process of placing the workpiece onto the fixture is unstable, especially with manual loading and unloading. Both flat plate fixtures and vertical plate fixtures have this problem, but it is more unstable with vertical plate fixtures. On a flat plate fixture, the workpiece is placed flat, and as long as the positioning hole is inserted into the spring taper pin, the workpiece will be initially positioned under its own weight. However, on a vertical plate fixture, the workpiece is hung on the fixture. After the worker releases their hand, the workpiece is easily tilted downwards due to the pushing action of the spring taper pin and its own weight. Most vertical plate fixtures are designed with an anti-tilting mechanism. Because of this mechanism, loading and unloading are inconvenient, and the workpiece remains basically stationary even if it is not placed correctly. If the worker does not pay attention, they will not notice the inaccurate workpiece positioning. This is because, as Figure 6 As shown, in the existing positioning mechanism, the downward stroke of spring b7 is unlimited, meaning the spring taper pin can be completely pressed below the support surface. When the workpiece b1 is not accurately clamped, the support surface and the blank positioning surface may partially align. However, in reality, one or two spring taper pins are not in the positioning hole and cannot perform their positioning function. Furthermore, all three air detection ports b8 are covered by the blank positioning surface. In this situation, the air detection value will still show as qualified, causing misjudgment and resulting in defective product processing and machine collisions. In addition, as... Figure 7 As shown, the positioning part of the support block a1 in the current positioning mechanism is characterized by a raised step a4, and the top surface of step a4 is the support surface. Figure 7 The second support surface (b4) is shown in the diagram. The positions of the air detection ports (b8) on the three support surfaces of the positioning mechanism are randomly arranged and irregular. When workpiece b1 is clamped, there may be one or two spring-loaded pins (…). Figure 7As shown, the second spring taper pin (b5) is not in the positioning hole and does not support any surface of the workpiece b1. At this time, the positioning and limiting of the spring taper pin are ineffective, and the air inspection port b8 is just positioned by the blank positioning surface ( Figure 7 As shown in the image, the second blank positioning surface Z2 is covered, and the air detection value shows as qualified. This means that even when the workpiece b1 is not clamped accurately, the air detection value may still show as qualified, resulting in unqualified product processing and machining accidents. Figure 6 and Figure 7 The two scenarios shown further increase the risk of misjudgment. Summary of the Invention

[0006] The technical problem to be solved by this utility model is to provide a dual error-proof fixture positioning mechanism, which effectively reduces the possibility of misjudgment in the error-proof gas detection by setting a lower stroke limit structure of the spring cone pin and optimizing the position of the three gas detection ports.

[0007] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows: a dual-proof fixture positioning mechanism, comprising three positioning mechanisms dispersedly installed on a flat plate in a flat plate fixture or on a vertical plate in a vertical plate fixture. Each positioning mechanism includes a positioning part and a pneumatic detection part. The positioning part includes a support block with a raised step. The top surface of the raised step serves as a support surface for contacting the positioning surface on the workpiece. Each of the support blocks in two of the positioning mechanisms is provided with a spring-loaded tapered pin for insertion into a positioning hole on the workpiece. The pneumatic detection part includes... The air detection port placed on the support surface is characterized in that: the spring tapered pin is equipped with a lower stroke limiting structure, which limits the spring tapered pin from being pressed down to the limit position by the positioning surface on the workpiece when it is not accurately inserted into the positioning hole on the workpiece, thereby supporting the workpiece and preventing the support surface and the positioning surface on the workpiece from fitting together, thus exposing the air detection port and achieving the first layer of error prevention; the air detection port is close to the edge of the support surface on which it is located, and the positions of the air detection ports in the three positioning mechanisms are designed in a correlation manner, so that when the workpiece is misaligned, one of the air detection ports will be exposed, achieving the second layer of error prevention.

[0008] The support block has a pin hole adapted to the pin body of the spring tapered pin and a cavity adapted to the pin tail of the spring tapered pin along its longitudinal direction. The pin hole and the cavity are connected as one piece and penetrate the support surface and the bottom surface of the support block. The lower stroke limiting structure includes a limiting sleeve disposed in the cavity. A spring is disposed between the pin tail of the spring tapered pin and the bottom end of the limiting sleeve. In the extended state of the spring, there is a lower limit stroke between the top end of the limiting sleeve and the end face of the pin tail of the spring tapered pin, and the length of the head of the pin body of the spring tapered pin protruding from the support surface is greater than the lower limit stroke, so that after the spring tapered pin is pressed down to the limit position, the head of the pin body of the spring tapered pin is still exposed on the support surface. By adding a limiting sleeve to limit the downward movement of the spring tapered pin, and by limiting the lower limit stroke, it is ensured that after the spring tapered pin is pressed down to the limit position, the head of the pin body of the spring tapered pin is still exposed on the support surface, which can support the workpiece. In the specific design, the lower limit stroke under ideal positioning conditions can be designed based on the size and dimensional error of the positioning holes on the workpiece. For example, if the lower limit stroke is designed to be 2mm, the length of the head of the spring taper pin protruding from the support surface in the spring extended state is 5.5mm. The spring provides the restoring force for the spring taper pin to return to its original shape. To avoid improper assembly by assemblers and to simplify the structure, it is not recommended to use a threaded adjustment spring force; instead, the spring force should be designed directly according to the requirements.

[0009] The bottom end of the limiting sleeve is closed, and the space between the bottom end of the limiting sleeve and the tail end of the spring cone pin forms a spring cavity. This structure limits the movement space of the spring.

[0010] A bottom seal is installed on the bottom surface of the support block, which closes the bottom port of the cavity. The space between the bottom seal and the tail of the spring cone pin forms a spring cavity. This structure limits the movement space of the spring and is usually chosen for its ease of assembly.

[0011] The positions of the three air detection ports are designed such that the center lines of the three air detection ports form a maximum triangle or a minimum triangle. This makes it easy for one of the air detection ports to be exposed no matter which direction the workpiece shifts. However, for design and processing convenience, they can be arranged in a positive up-down or left-right orientation according to the actual direction of the fixture, which can also achieve a good error prevention effect.

[0012] In the vertical plate fixture, the air detection port is located directly above, directly below, directly to the left, or directly to the right of the support surface relative to its center point. For the support surface located at the top of the vertical plate, one air detection port is located directly above it; for the support surface located at the bottom of the vertical plate, one air detection port is located directly below it; and for the remaining support surface, one air detection port is located directly above it. In vertical plate fixtures, because workpieces are more prone to downward misalignment, the air inspection port on the uppermost support surface of the vertical plate is positioned directly above the center point of that support surface. Similarly, the air inspection port on the lowermost support surface is positioned directly below the center point of that support surface. The position of the air inspection port on the last support surface satisfies the following condition: the position furthest from the center line connecting the other two air inspection ports is selected as the positive direction position closest to the furthest position. The positive direction position can be one of the following: directly above, directly below, directly to the left, or directly to the right. However, when the furthest position is close to the directly above position, the directly above position is preferred to reduce the risk of workpiece downward misalignment. Therefore, in actual design, this air inspection port can be directly positioned at the directly above position.

[0013] Compared with the prior art, the advantages of this utility model are:

[0014] By setting a lower stroke limit structure, the air detection port can be exposed when the spring taper pin is not accurately inserted into the positioning hole on the workpiece. By optimizing the position of the three air detection ports, the air detection ports can be exposed when the workpiece is misaligned, achieving double error prevention. When the air detection port is exposed, the air detection value is displayed as unqualified, successfully detecting inaccurate workpiece clamping and positioning, effectively reducing the possibility of misjudgment of error prevention air detection, and minimizing product processing defects and machining accidents caused by incorrect clamping posture. Attached Figure Description

[0015] Figure 1 A schematic diagram of the composition of an existing positioning mechanism (only a simplified illustration of the support block is given);

[0016] Figure 2 A schematic diagram of the three blank positioning surfaces, one blank conical hole, and one blank waist-shaped hole on the workpiece when the positioning mechanism of the OP10 model fixture adopts the positioning method of one-face two-pin.

[0017] Figure 3 This is a schematic diagram showing the first blank positioning surface in contact with the first support surface and the first spring cone pin inserted into the conical hole of the blank when the positioning mechanism of the OP10 model fixture adopts a one-sided two-pin positioning method.

[0018] Figure 4A schematic diagram showing the second blank positioning surface in contact with the second support surface and the second spring tapered pin inserted into the blank's waist-shaped hole when the positioning mechanism of the OP10 model fixture adopts a one-sided two-pin positioning method.

[0019] Figure 5 A schematic diagram showing the contact between the third blank positioning surface and the third support surface when the positioning mechanism of the OP10 model fixture adopts a one-sided two-pin positioning method;

[0020] Figure 6 This is a schematic diagram showing a situation where the support surface and the blank positioning surface are partially aligned in the existing positioning mechanism, the spring cone pin is not in the positioning hole, and the air detection port is covered by the blank positioning surface.

[0021] Figure 7 This is a schematic diagram of a situation where the spring taper pin in the existing positioning mechanism is not in the positioning hole and does not support any surface of the workpiece, and the air inspection port is covered by the positioning surface of the blank.

[0022] Figure 8 A schematic diagram of three positioning mechanisms installed on a flat or upright plate;

[0023] Figure 9 A schematic diagram of a positioning mechanism equipped with a spring-loaded tapered pin;

[0024] Figure 10 This is a schematic diagram of a positioning mechanism without a spring-loaded cone pin.

[0025] Figure 11 for Figure 9 A schematic diagram of the exploded structure shown;

[0026] Figure 12 for Figure 9 A longitudinal sectional view of the structure shown.

[0027] Figure 13 A schematic diagram showing the accurate insertion of a spring taper pin into a positioning hole on a workpiece.

[0028] Figure 14 A longitudinal sectional view showing when the spring taper pin is not accurately inserted into the locating hole on the workpiece. Figure 1 ;

[0029] Figure 15 A longitudinal sectional view showing when the spring taper pin is not accurately inserted into the locating hole on the workpiece. Figure 2 ;

[0030] Figure 16 This is a schematic diagram showing the relative positions of the three positioning mechanisms on the upright plate. Detailed Implementation

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

[0032] like Figures 8 to 16 As shown, this utility model proposes a dual-proof error-proof clamping positioning mechanism, which can be used in OP10 model flat plate clamps and vertical plate clamps, such as... Figure 8 As shown, it consists of three positioning mechanisms D distributed on the flat plate or the vertical plate L of the flat plate fixture. Each positioning mechanism D includes a positioning part and a gas detection part. The positioning part includes a support block 1 with a raised step 11. The top surface of the raised step 11 serves as a support surface 12 for engaging with the positioning surface 91 on the workpiece 9. Each of the support blocks 1 in two positioning mechanisms D is provided with a spring taper pin 2 for insertion into the positioning hole 92 on the workpiece 9 (see...). Figure 9 In another positioning mechanism D, the support block 1 does not have a spring cone pin 2 (see...). Figure 10 The air detection section includes an air detection port 3 located on the support surface 12. The spring cone pin 2 is equipped with a lower stroke limiting structure 4. This lower stroke limiting structure 4 prevents the spring cone pin 2 from being accurately inserted into the positioning hole 92 on the workpiece 9. Instead, it is pressed downwards by the positioning surface 91 on the workpiece 9 to the limit position, thus supporting the workpiece 9 and preventing the support surface 12 and the positioning surface 91 on the workpiece 9 from fitting together. This exposes the air detection port 3. Figure 14 and Figure 15 As shown, this achieves the first level of error prevention and can solve... Figure 6 The problem shown is that the air sensor port 3 is close to the edge of its supporting surface 12, making it easy for the air sensor port 3 to be exposed when the workpiece 9 is misaligned. The positional correlation design of the air sensor ports 3 in the three positioning mechanisms D ensures that one air sensor port 3 will be exposed when the workpiece 9 is misaligned, so that no matter which direction the workpiece 9 is offset, the air sensor port 3 will always be exposed, achieving a second layer of error prevention and solving the problem. Figure 7 The problem shown is that the air detection port 3 is connected to the air sensor through the air detection channel 5. The air sensor monitors the air detection value and determines whether the workpiece 9 is accurately clamped and positioned.

[0033] Further restrictions, such as Figure 11 and Figure 12As shown, the support block 1 has a pin hole 13 that matches the pin body 21 of the spring cone pin 2 and a cavity 14 that matches the pin tail 22 of the spring cone pin 2 along the longitudinal direction. The pin hole 13 and the cavity 14 are connected as one unit and penetrate the support surface 12 and the bottom surface of the support block 1. The lower stroke limiting structure 4 includes a limiting sleeve 41, which is disposed in the cavity 14. A spring 6 is disposed between the pin tail 22 of the spring cone pin 2 and the bottom end of the limiting sleeve 41. When the spring 6 is extended, there is a lower limit stroke d between the top end of the limiting sleeve 41 and the end face of the pin tail 22 of the spring cone pin 2. The length W of the head of the pin body 21 of the spring cone pin 2 protruding from the support surface 12 is greater than the lower limit stroke d, so that after the spring cone pin 2 is pressed down to the limit position, the head of the pin body 21 of the spring cone pin 2 is still protruding from the support surface 12. By adding a limiting sleeve 41, the downward movement of the spring cone pin 2 is limited. Furthermore, by limiting the lower limit stroke d, it is ensured that after the spring cone pin 2 is pressed down to its limit position, the head of the pin body 21 of the spring cone pin 2 remains exposed on the support surface 12, thus supporting the workpiece 9. In specific design, the lower limit stroke d can be designed according to the size error of the positioning hole 92 on the workpiece 9, under ideal positioning conditions. For example, if the lower limit stroke d is designed to be 2mm, the length W of the head of the pin body 21 of the spring cone pin 2 exposed on the support surface 12 when the spring 6 is extended is 5.5mm. The spring 6 provides a restoring force for the spring cone pin 2 to return to its original shape. To avoid improper assembly by the assembler and to simplify the structure, it is not recommended to use a threaded adjustment spring force for the spring 6; instead, the spring force of the spring 6 should be designed directly according to requirements.

[0034] Further, the bottom end of the limiting sleeve 41 is closed, and the space between the bottom end of the limiting sleeve 41 and the pin tail 22 of the spring cone pin 2 forms a spring cavity 7. This structure limits the movement space of the spring 6; or a bottom seal 15 is added to the bottom surface of the support block 1, the bottom seal 15 closes the bottom port of the cavity 14, and the space between the bottom seal 15 and the pin tail 22 of the spring cone pin 2 forms a spring cavity 7. This structure limits the movement space of the spring 6. This structure is usually selected because it is more convenient to assemble.

[0035] As a preferred option, the positional association design of the three air detection ports 3 is such that the center line connecting the three air detection ports 3 forms a maximum triangle or a minimum triangle. This makes it easy for one of the air detection ports 3 to be exposed no matter which direction the workpiece 9 shifts. This is very suitable for flat plate fixtures. However, for design and processing convenience, the arrangement can be positive up and down or left and right according to the actual direction of the fixture, which can also achieve a good error prevention effect.

[0036] As a preferred option, such as Figure 16As shown, in the vertical plate fixture, the air detection port 3 is located on the support surface 12 at a position directly above, directly below, directly to the left, or directly to the right of its center point. For the support surface 12 located at the top of the vertical plate L, an air detection port 3 is set at its top position; for the support surface 12 located at the bottom of the vertical plate L, an air detection port 3 is set at its bottom position; and for the remaining support surface 12, an air detection port 3 is set at its top position. In the vertical plate fixture, because workpiece 9 is more likely to be misaligned downwards, the air inspection port 3 on the uppermost support surface 12 of the vertical plate L is set directly above the center point of the support surface 12. The air inspection port 3 on the lowermost support surface 12 of the vertical plate L is set directly below the center point of the support surface 12. The position of the air inspection port 3 on the last support surface 12 satisfies the following condition: the position furthest from the center line connecting the other two air inspection ports 3 is selected as the positive direction position closest to the furthest position. The positive direction position can be one of the positions directly above, directly below, directly to the left, or directly to the right. However, when the furthest position is close to the position directly above, the position directly above is preferred to reduce the risk of workpiece 9 being misaligned downwards. Therefore, in actual design, this air inspection port 3 can be directly set at the position directly above.

Claims

1. A dual-proof fixture positioning mechanism, comprising three positioning mechanisms dispersedly installed on a flat plate in a flat plate fixture or on a vertical plate in a vertical plate fixture, each positioning mechanism including a positioning part and an air detection part, the positioning part including a support block having a raised step, the top surface of the raised step serving as a support surface for abutting against a positioning surface on the workpiece, wherein each of the support blocks in two of the positioning mechanisms is provided with a spring-loaded tapered pin for insertion into a positioning hole on the workpiece, the air detection part including an air detection port provided on the support surface, characterized in that: The spring-loaded tapered pin is equipped with a lower stroke limiting structure. This structure prevents the spring-loaded tapered pin from being accurately inserted into the positioning hole on the workpiece. Instead, it is pressed down by the positioning surface on the workpiece to the limit position, supporting the workpiece and preventing the supporting surface from contacting the positioning surface on the workpiece. This exposes the air detection port, achieving the first layer of error prevention. The air detection port is located near the edge of the supporting surface. The positions of the air detection ports in the three positioning mechanisms are designed in a correlated manner, ensuring that one of the air detection ports will be exposed when the workpiece is misaligned, achieving the second layer of error prevention.

2. The dual error-proof clamp positioning mechanism according to claim 1, characterized in that: The support block has a pin hole adapted to the pin body of the spring cone pin and a cavity adapted to the pin tail of the spring cone pin along the longitudinal direction. The pin hole and the cavity are connected as one piece and penetrate the support surface and the bottom surface of the support block. The lower stroke limiting structure includes a limiting sleeve, which is disposed in the cavity. A spring is disposed between the pin tail of the spring cone pin and the bottom end of the limiting sleeve. When the spring is extended, there is a lower limit stroke between the top end of the limiting sleeve and the end face of the pin tail of the spring cone pin. The length of the head of the pin body of the spring cone pin protruding from the support surface is greater than the lower limit stroke, so that after the spring cone pin is pressed down to the limit position, the head of the pin body of the spring cone pin is still protruding from the support surface.

3. The dual error-proof clamp positioning mechanism according to claim 2, characterized in that: The bottom end of the limiting sleeve is closed, and the space between the bottom end of the limiting sleeve and the tail of the spring cone pin forms a spring cavity.

4. The dual error-proof clamp positioning mechanism according to claim 2, characterized in that: A bottom seal is installed on the bottom surface of the support block, which closes the bottom port of the cavity. The space between the bottom seal and the tail of the spring cone pin forms a spring cavity.

5. A dual-proof error-proof clamp positioning mechanism according to any one of claims 1 to 4, characterized in that: The positions of the three gas detection ports are designed such that the center lines connecting the three gas detection ports form either a maximum triangle or a minimum triangle.

6. The dual error-proof clamp positioning mechanism according to claim 5, characterized in that: In the vertical plate fixture, the air detection port is located directly above, directly below, directly to the left, or directly to the right of the support surface relative to its center point. For the support surface located at the top of the vertical plate, one air detection port is located directly above it; for the support surface located at the bottom of the vertical plate, one air detection port is located directly below it; and for the remaining support surface, one air detection port is located directly above it.

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