An automated positioning device

Abstract

This invention discloses an automated positioning device, comprising: a base; a first cylinder disposed on the base; a flipping bracket including a lever portion and a flipping frame connected to the lever portion; the lever portion is rotatably connected to the base, and one end of the lever portion is hinged to the piston rod of the first cylinder; a feeding push rod connected to the other end of the lever portion through a first transmission assembly; a third cylinder disposed on the flipping frame; a second cylinder bracket connected to the piston rod of the third cylinder to perform linear reciprocating motion with the extension and retraction of the piston rod of the third cylinder, and a support block fixedly disposed on the second cylinder bracket; a second cylinder disposed on the second cylinder bracket, the piston rod of the second cylinder being connected to a positioning assembly through a second transmission assembly, the positioning assembly switching between a closed position and an open position with the extension and retraction of the piston rod of the second cylinder, wherein in the closed position, the positioning assembly and the support block work together to clamp the workpiece to be positioned.

Description

Technical Field

[0001] This invention relates to a mechanical device, and more particularly to a device for positioning a workpiece. Background Technology

[0002] The automatic measuring machine for connecting rod products is the last process step in the entire connecting rod product manufacturing process. Only after the connecting rod products are measured, weighed, and grouped on the automatic measuring machine is the entire manufacturing process considered complete.

[0003] In order to measure the connecting rod product on the automatic measuring machine, the connecting rod product needs to be moved to the measuring station.

[0004] Currently, manual handling is often used to move connecting rod products onto automatic measuring machines, but this method is inefficient.

[0005] In addition, some advanced existing technologies use robots or robotic arms to transport linkage products onto automatic measuring machines. However, in actual use, the operation of such mechanisms is not ideal. During the transportation process, problems such as uneven operation and easy damage often occur. There are many faults, requiring frequent maintenance, which affects the normal operation of automatic measuring machines. Summary of the Invention

[0006] The purpose of this invention is to provide an automated positioning device that can be used in conjunction with an automatic measuring machine for connecting rod products, thereby solving the problems of low efficiency or high cost of existing solutions.

[0007] To achieve the above objectives, the present invention proposes an automated positioning device, comprising:

[0008] Fixed base;

[0009] The first cylinder is mounted on the base;

[0010] A flipping bracket includes a lever and a flipping frame connected to the lever; the middle part of the lever is rotatably connected to the base via a lever pivot, and one end of the lever is hinged to the piston rod of the first cylinder, so that the flipping frame switches between a horizontal position and a vertical position as the piston rod of the first cylinder extends and retracts.

[0011] The feeding push rod is connected to the other end of the lever part through the first transmission assembly, so that the feeding push rod performs linear reciprocating motion with the extension and retraction of the piston rod of the first cylinder;

[0012] The third cylinder is mounted on the tilting frame;

[0013] The second cylinder bracket is connected to the piston rod of the third cylinder to perform linear reciprocating motion as the piston rod of the third cylinder extends and retracts. A support block for accommodating the workpiece to be positioned is fixed on the second cylinder bracket.

[0014] The second cylinder is mounted on the second cylinder bracket. The piston rod of the second cylinder is connected to the positioning component through the second transmission component. The positioning component switches between the closed position and the open position as the piston rod of the second cylinder extends and retracts. In the closed position, the positioning component and the support block work together to clamp the workpiece to be positioned.

[0015] Furthermore, the automated positioning device of the present invention further includes a feeding component, which comprises:

[0016] A magnetic conveyor support, which is equipped with a conveyor belt and several magnetic adsorption components arranged along the conveyor belt;

[0017] A magnetic conveying rod extends from the magnetic conveying bracket and points toward the second cylinder bracket.

[0018] Furthermore, in the automated positioning device of the present invention, the first cylinder is rotatably mounted on the base.

[0019] Furthermore, in the automated positioning device of the present invention, the other end of the lever portion is provided with a lever portion groove; the first transmission assembly includes:

[0020] A fixed guide rail base, on which a guide rail is mounted;

[0021] A slider is slidably mounted on the guide rail base along the guide rail. The feeding push rod is connected to the slider, and the slider is provided with a slider pin.

[0022] The connecting rod, the first end of which is adapted to the lever groove via a first connecting rod pin;

[0023] A lever, the middle of which is rotatably mounted on the guide rail seat via a lever pivot, has a first groove at its head end and a second groove at its tail end. The head end of the lever is adapted to be connected to the second connecting rod pin at the tail end of the connecting rod via the first groove, and the tail end of the lever is adapted to be connected to the slider pin via the second groove.

[0024] Furthermore, in the automated positioning device of the present invention, the first transmission component further includes a fixedly disposed connecting rod seat, which has a connecting rod hole, and the connecting rod passes through the connecting rod hole and is disposed on the connecting rod seat.

[0025] Furthermore, in the automated positioning device of the present invention, the second transmission component includes:

[0026] The first rack is connected to the piston rod of the second cylinder;

[0027] A gear, which is rotatably mounted on the second cylinder bracket and meshes with the first rack;

[0028] The second rack is located on the other side of the gear relative to the first rack and meshes with the gear. The second rack is connected to the positioning assembly.

[0029] Furthermore, in the automated positioning device of the present invention, the positioning component includes:

[0030] A cam plate with a camshaft is disposed relative to the support block. The camshaft is connected to the second rack. A helical groove is provided on the circumferential surface of the camshaft. The helical groove is adapted to a pin provided on the second cylinder bracket so that: the cam plate moves linearly in the same direction as the linear movement of the second rack under the drive of the linear reciprocating motion of the second rack, and also rotates around the axis of the camshaft to switch between the closed position and the open position;

[0031] A positioning rod is provided, which passes through the cam plate, and the first end of the positioning rod is inserted into the positioning hole of the workpiece to be positioned.

[0032] Furthermore, in the automated positioning device of the present invention, the positioning component further includes:

[0033] A movable plate whose shape is adapted to the cam plate is concentrically set and connected to the cam plate by a connecting pin. The movable plate is set between the support block and the cam plate, and the positioning rod is also set through the movable plate.

[0034] Furthermore, in the automated positioning device of the present invention, a spring is provided between the cam plate and the movable plate to apply elastic force in the axial direction of the cam plate.

[0035] Furthermore, in the automated positioning device of the present invention, the positioning rod includes:

[0036] Several first positioning rods are set at the head of the workpiece to be positioned;

[0037] The second positioning rod is located at the tail of the workpiece to be positioned.

[0038] The automated positioning device described in this invention has the following advantages and beneficial effects:

[0039] The automated positioning device described in this invention can be used in conjunction with an automatic measuring machine for connecting rod products, solving the problems of low efficiency or high cost of existing solutions.

[0040] The automated positioning device described in this invention occupies little space, has a simple structure, is easy to manufacture and maintain, has high reliability, and is convenient to use and operate, which can greatly improve the operational stability and reliability of automatic measuring machines. Attached Figure Description

[0041] Figure 1 The diagram shows a three-dimensional structural schematic of the automated positioning device according to one embodiment of the present invention from one perspective.

[0042] Figure 2 This diagram shows a three-dimensional structural schematic of the automated positioning device according to one embodiment of the present invention from another perspective.

[0043] Figure 3 The diagram shows a three-dimensional view of the flip-up bracket of the automated positioning device of the present invention in one embodiment.

[0044] Figure 4 The diagram shows a three-dimensional view of the flip-up bracket of the automated positioning device of the present invention in one embodiment, viewed from another perspective.

[0045] Figure 5 Showing Figure 2 A magnified view of a section at point I.

[0046] Figure 6 A three-dimensional structural diagram of the support block of the automated positioning device according to one embodiment of the present invention is shown.

[0047] Figure 7 This diagram shows a three-dimensional structural schematic of the feeding component of the automated positioning device according to one embodiment of the present invention.

[0048] Figure 8 A schematic diagram of the internal structure of the magnetic conveying bracket of the automated positioning device of the present invention is shown in one embodiment.

[0049] Figure 9 The diagram shows a schematic representation of the guide rail base of the automated positioning device according to one embodiment of the present invention.

[0050] Figure 10 A schematic diagram of the linkage structure of the automated positioning device according to one embodiment of the present invention is shown.

[0051] Figure 11 The diagram shows a three-dimensional structural schematic of the second cylinder bracket in one embodiment of the automated positioning device of the present invention.

[0052] Figure 12A schematic diagram of the cam plate in one embodiment of the automated positioning device of the present invention is shown.

[0053] Figure 13 Showing Figure 1 A magnified view of a section at point III.

[0054] Figure 14 The diagram shows a schematic representation of the movable plate in one embodiment of the automated positioning device of the present invention.

[0055] Figure 15 A cross-sectional view of the automated positioning device according to one embodiment of the present invention is shown.

[0056] Figure 16 Showing Figure 15 A magnified view of section IV in the middle.

[0057] Figure 17 A schematic diagram of the structure of the first positioning rod in one embodiment of the automated positioning device of the present invention is shown. Detailed Implementation

[0058] The automated positioning device of the present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments. However, such explanation and description do not constitute an undue limitation on the technical solution of the present invention.

[0059] Figure 1 The diagram shows a three-dimensional structural schematic of the automated positioning device according to one embodiment of the present invention from one perspective.

[0060] Figure 2 This diagram shows a three-dimensional structural schematic of the automated positioning device according to one embodiment of the present invention from another perspective.

[0061] like Figure 1 and Figure 2 As shown, in some embodiments, the automated positioning device of the present invention includes: a fixedly mounted base 1; a first cylinder bracket 21 rotatably mounted on the base 1 via a base pivot 22; and a first cylinder 23 mounted on the base 1 via the first cylinder bracket 21, with its tail fixedly connected to the first cylinder bracket 21 via an angle iron 24.

[0062] In addition, the automated positioning device also includes a flipping bracket 3. Figure 3 The diagram shows a three-dimensional view of the flip-up bracket of the automated positioning device of the present invention in one embodiment. Figure 4 The diagram shows a three-dimensional view of the flip-up bracket of the automated positioning device of the present invention in one embodiment, viewed from another perspective.

[0063] like Figure 3 and Figure 4 As shown, the flipping bracket 3 includes a lever portion 31 and a flipping frame 32 connected to the lever portion 31; wherein the middle part of the lever portion 31 is rotatably connected to the base 1 via a lever portion pivot 33, as shown. Figure 5 As shown, one end of the lever shaft 33 is axially limited by a snap ring 331, allowing the tilting bracket 3 to rotate around the lever shaft 33. The upper end of the lever 31 is hinged to the head of the piston rod 231 of the first cylinder 23 via a clearance-fitted shaft and hole. The third cylinder 4 is mounted on the tilting frame 32. As the piston rod of the first cylinder 23 extends and retracts, the tilting frame moves in a horizontal position (e.g., ...). Figure 1 and Figure 2 Switching between the position shown in the figure and the vertical workstation (not shown in the figure).

[0064] Continue reading Figure 1 and Figure 2 The feeding push rod 5 is connected to the other end of the lever part 31 through the first transmission assembly, so that the feeding push rod 5 can perform linear reciprocating motion with the extension and retraction of the piston rod 231 of the first cylinder 23. The second cylinder bracket 61 is connected to the piston rod of the third cylinder 4, so that it performs linear reciprocating motion with the extension and retraction of the piston rod of the third cylinder 4. The second cylinder bracket 61 is fixedly provided with a device for accommodating the workpiece to be positioned. Figure 6 The support block 7 is shown; the second cylinder 62 is mounted on the second cylinder bracket 61, and the piston rod of the second cylinder 62 is connected to the positioning component through the second transmission component. The positioning component switches between the closed position and the open position as the piston rod of the second cylinder 62 extends and retracts. In the closed position, the positioning component and the support block 7 work together to clamp the workpiece P to be positioned.

[0065] In addition, in order to achieve the initial loading of the workpiece to be positioned (e.g., a connecting rod product) into the aforementioned automated positioning device, such as Figure 1 and Figure 2 and Figure 7 As shown, the automated positioning device of the present invention may preferably also include a feeding assembly, which includes: a magnetic conveying bracket 81 and a magnetic conveying rod 82, the magnetic conveying rod 82 extending from the magnetic conveying bracket 81 and pointing towards the second cylinder bracket 61.

[0066] Figure 8 A schematic diagram of the internal structure of the magnetic conveying bracket of the automated positioning device of the present invention is shown in one embodiment.

[0067] like Figure 8As shown, in some embodiments, the magnetic conveying bracket 81 is provided with a conveyor belt 811, which is conveyed by guide wheels 812. Several magnetic adsorption elements 813 arranged along the conveyor belt are provided on the conveyor belt. The magnetic adsorption elements 813 are permanent magnets that can adsorb the workpiece to be positioned. The magnetic adsorption elements 813 are spaced apart, so intermittent feeding can be achieved.

[0068] Continue reading Figure 1 and Figure 2 In some embodiments, the first transmission assembly connected to the feeding push rod 5 may include: a fixedly mounted guide rail seat 91, such as... Figure 9 As shown, a guide rail 911 is provided on the guide rail base 91; the slider 92 is slidably disposed on the guide rail base 91 along the guide rail, such as... Figure 7 As shown, the feeding push rod 5 is connected to the slider 92, and the slider 92 is provided with a slider pin 921. The connecting rod 93 is set through a fixed connecting rod seat 95. The connecting rod 93 passes through the hole of the connecting rod seat 95. During installation, the connecting rod 93 can be disassembled into two parts and then spliced ​​together.

[0069] Figure 10 A schematic diagram of the linkage structure of the automated positioning device according to one embodiment of the present invention is shown.

[0070] like Figure 10 As shown, the first end of the connecting rod 93 is adapted to the lever slot of the lever part 31 of the flip bracket 3 via the first connecting rod pin 931; the tail end of the connecting rod 93 is adapted to the first end of the lever 94 via the second connecting rod pin 932; the middle part of the lever 94 is rotatably mounted on the guide rail seat 91 via the lever pivot 912; and the tail end of the lever 94 is adapted to the slider pin 921 via the second slide groove.

[0071] Continue reading Figure 1 and Figure 2 In some embodiments, the second transmission assembly connected to the piston rod of the second cylinder includes:

[0072] The first rack 101 is connected to the piston rod of the second cylinder 62; the gear 102 is rotatably mounted on the second cylinder bracket 61 via the gear shaft 104 and meshes with the first rack 101; the second rack 103 is located on the other side of the gear 102 relative to the first rack 101 and meshes with the gear 102, and the second rack 103 is connected to the positioning assembly.

[0073] Figure 11 The diagram shows a three-dimensional structural schematic of the second cylinder bracket in one embodiment of the automated positioning device of the present invention.

[0074] In some embodiments, the second cylinder 62 can be fixed to the second cylinder bracket 61 by an angle iron. The first rack 101 has a dovetail slider that can slide into contact with the dovetail groove 611 on the second cylinder bracket 61. Furthermore, the second rack 103 can also engage with the dovetail groove on the second cylinder bracket 61 via a dovetail slider on one side. The guide rod 612 on the second cylinder bracket 61 serves to guide and support the second cylinder bracket as it moves linearly under the drive of the third cylinder.

[0075] Continue reading Figure 1 and Figure 2 In some embodiments, the positioning component for positioning the workpiece to be positioned includes a cam plate 111 having a cam shaft 112, which is disposed relative to the support block 7.

[0076] like Figure 12 and Figure 13 As shown, the camshaft 112 is connected to the second rack 103. The circumferential surface of the camshaft 112 is provided with a spiral groove 1121. The spiral groove 1121 is adapted to the pin 113 provided on the second cylinder bracket 61 so that the cam plate 111 moves linearly in the same direction as the linear movement of the second rack 103 under the drive of the linear reciprocating motion of the second rack, and also rotates around the axis of the camshaft 112, thereby realizing the switching between the closed position and the open position.

[0077] like Figure 13 , Figure 14 , Figure 15 and Figure 16 As shown, a movable plate 114, whose shape is adapted to the cam plate 111, is concentrically arranged and connected to the cam plate 111 via a connecting pin 1141. A nut 118 is provided at the end of the connecting pin 1141, and a spring 117 is sleeved on the connecting pin 1141. The spring 117 is disposed between the cam plate 111 and the movable plate 114, and the movable plate 114 is disposed between the support block 7 and the cam plate 111. Figure 17 The first positioning rod 115, as shown, passes through a square hole in the movable plate and the cam plate, and is clearance-fitted with the square hole. A nut is screwed onto the thread at the tail of the first positioning rod, and the end face of the thread contacts the end face of the first positioning rod. In some embodiments, a first positioning rod spring 1151 may also be fitted over the first positioning rod, and the first positioning rod spring 1151 is supported between the stepped surface of the head of the first positioning rod and the movable plate 114. Figure 17 As shown, the head of the first positioning rod 115 is conical and faces outward, with the three points forming a circle. The first positioning rod 115 is located at the head of the workpiece to be positioned, the movable plate, and the cam plate.

[0078] In addition, a second positioning rod 116 is located at the tail of the workpiece to be positioned, the movable plate, and the cam plate. The second positioning rod passes through the large square holes at the tail of the movable plate and the cam plate and is clearance-fitted with the two square holes. Similarly, a nut is screwed onto the thread at the tail of the second positioning rod, and the end face of the thread contacts the end face of the tail of the second positioning rod. In some embodiments, a second positioning rod spring 1161 may also be fitted over the second positioning rod 116, and the second positioning rod spring 1161 is supported between the stepped surface of the head of the second positioning rod and the movable plate 114.

[0079] The automatic positioning device is designed to cause the workpiece to be positioned (e.g., a connecting rod product) arranged on the feeding assembly to be flipped from a position where the center line of its large hole is horizontal to a position where the center line of its large hole is vertical, and then measured by an automatic measuring machine (not involved in this invention) in this state, and then by a robotic arm or robot that is not within the scope of this invention after the measurement is completed.

[0080] For this purpose, the automatic positioning device operates as follows:

[0081] (1) The piston rod of the first cylinder 23 retracts, causing the tilting bracket 3 to move from the position shown in the image. Figure 1 and Figure 2 The horizontal position shown is flipped 90° to the vertical position. At this time, the workpiece (such as a connecting rod product) set on the second cylinder support is flipped to the measuring position (i.e., the vertical position) along with the second cylinder support. At the same time, the third cylinder extends, driving the second cylinder support and the components set on it to extend upward. Simultaneously, the piston rod of the second cylinder retracts, causing the cam plate to switch to the closed position. In this state, the automatic measuring device can measure the workpiece. At the same time, the feeding push rod 5 extends towards the second cylinder support under the action of the retraction of the first cylinder, thereby pushing the next connecting rod product waiting on the magnetic conveying rod 82 towards the second cylinder support.

[0082] (2) Then the piston rod of the second cylinder 62 extends, causing the cam plate to switch to the open position, and then the robot arm can be used to take away the connecting rod product that has been measured.

[0083] (3) Then the piston rod of the third cylinder 4 retracts, causing the second cylinder bracket to move down as a whole;

[0084] (4) Then the piston rod of the first cylinder 23 extends, driving the flipping bracket 3 to return from the vertical position to the horizontal position, the center line of the second cylinder is horizontal, and at the same time, it drives the feeding push rod 5 to retract (i.e. move away from the first cylinder).

[0085] (5) Then the piston rod of the third cylinder 4 extends, causing the second cylinder bracket to extend horizontally.

[0086] (6) Then the piston rod of the second cylinder 62 retracts, driving the cam plate to switch to the closed position;

[0087] (7) Then the piston rod of the third cylinder 4 retracts;

[0088] (8) The feeding component starts intermittently, and the next connecting rod product is conveyed to the position where the magnetic conveying bracket and the magnetic conveying rod are connected;

[0089] (9) Return to step (1).

[0090] It should be noted that, in this embodiment, opening the cam plate means that: the second cylinder extends and moves the cam plate closer to the guide rail seat through gear transmission, while simultaneously driving the cam plate to rotate counterclockwise around the axis of the camshaft (viewed from the guide rail seat towards the first cylinder); thus, the first positioning rod and the second positioning rod can be inserted into the product connecting rod for positioning, and then the movable plate presses against the end face of the product connecting rod, so that the product connecting rod is in close contact with the support block 7, and the arc-shaped boss on the support block 7 can play a pre-positioning role.

[0091] Cam plate closing means that the second cylinder retracts, causing the cam plate to move away from the guide rail via gear transmission, while simultaneously causing the cam plate to rotate clockwise around the camshaft axis (viewed from the guide rail towards the first cylinder).

[0092] It should be noted that the prior art portion of the protection scope of this invention is not limited to the embodiments given in this application. All prior art that does not contradict the solution of this invention, including but not limited to prior patent documents, prior publications, prior public uses, etc., can be included in the protection scope of this invention.

[0093] Furthermore, the combination of the technical features in this case is not limited to the combination methods described in the claims of this case or the combination methods described in the specific embodiments. All technical features described in this case can be freely combined or combined in any way, unless they contradict each other.

[0094] It should also be noted that the embodiments listed above are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made thereto are those that can be directly derived or easily conceived by those skilled in the art from the content disclosed in the present invention, and should all fall within the protection scope of the present invention.

Claims

1. An automated positioning device, characterized in that, include: Fixed base; The first cylinder is mounted on the base; A flipping bracket includes a lever and a flipping frame connected to the lever; the middle part of the lever is rotatably connected to the base via a lever pivot, and one end of the lever is hinged to the piston rod of the first cylinder, so that the flipping frame switches between a horizontal position and a vertical position as the piston rod of the first cylinder extends and retracts. The feeding push rod is connected to the other end of the lever part through the first transmission assembly, so that the feeding push rod performs linear reciprocating motion with the extension and retraction of the piston rod of the first cylinder; The third cylinder is mounted on the tilting frame; The second cylinder bracket is connected to the piston rod of the third cylinder to perform linear reciprocating motion as the piston rod of the third cylinder extends and retracts. A support block for accommodating the workpiece to be positioned is fixed on the second cylinder bracket. A second cylinder is mounted on a second cylinder bracket. The piston rod of the second cylinder is connected to a positioning component via a second transmission assembly. The positioning component switches between a closed position and an open position as the piston rod of the second cylinder extends and retracts. In the closed position, the positioning component and a support block work together to clamp the workpiece to be positioned. The second transmission assembly includes: a first rack connected to the piston rod of the second cylinder; a gear rotatably mounted on the second cylinder bracket and meshing with the first rack; and a second rack located on the opposite side of the first rack and meshing with the gear. The second rack is connected to the positioning assembly; the positioning assembly includes: a cam plate with a camshaft, which is disposed relative to the support block, the camshaft being connected to the second rack, and a helical groove provided on the circumferential surface of the camshaft, the helical groove being adapted to a pin disposed on the second cylinder bracket, so that: the cam plate moves linearly in the same direction as the linear movement of the second rack under the drive of the linear reciprocating motion of the second rack, and also rotates around the axis of the camshaft to switch between the closed position and the open position; a positioning rod, which is disposed through the cam plate, the first end of the positioning rod being inserted into the positioning hole of the workpiece to be positioned; The feeding assembly includes: a magnetic conveying bracket with a conveyor belt and several magnetic adsorption components arranged along the conveyor belt; and a magnetic conveying rod extending from the magnetic conveying bracket and pointing towards the second cylinder bracket.

2. The automated positioning device as described in claim 1, characterized in that, The first cylinder is rotatably mounted on the base.

3. The automated positioning device as described in claim 1, characterized in that, The other end of the lever is provided with a lever groove; the first transmission assembly includes: A fixed guide rail base, on which a guide rail is mounted; A slider is slidably mounted on the guide rail base along the guide rail. The feeding push rod is connected to the slider, and the slider is provided with a slider pin. The connecting rod, the first end of which is adapted to the lever groove via a first connecting rod pin; A lever, the middle of which is rotatably mounted on the guide rail seat via a lever pivot, has a first groove at its head end and a second groove at its tail end. The head end of the lever is adapted to be connected to the second connecting rod pin at the tail end of the connecting rod via the first groove, and the tail end of the lever is adapted to be connected to the slider pin via the second groove.

4. The automated positioning device as described in claim 3, characterized in that, The first transmission assembly also includes a fixedly disposed connecting rod seat, which has a connecting rod hole, and the connecting rod passes through the connecting rod hole and is disposed on the connecting rod seat.

5. The automated positioning device as described in claim 1, characterized in that, The positioning component also includes: A movable plate whose shape is adapted to the cam plate is concentrically set and connected to the cam plate by a connecting pin. The movable plate is set between the support block and the cam plate, and the positioning rod is also set through the movable plate.

6. The automated positioning device as described in claim 5, characterized in that, A spring is provided between the cam plate and the movable plate to apply elastic force to the cam plate in the axial direction.

7. The automated positioning device as described in claim 1, characterized in that, The positioning rod includes: Several first positioning rods are set at the head of the workpiece to be positioned; The second positioning rod is located at the tail of the workpiece to be positioned.

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