Limiting device of reaming machine

Abstract

A limiting device of a reaming machine relates to a metal processing tool. The utility model relates to a ring rolling machine limiting device, in particular to a ring rolling machine limiting device, and aims to solve the problems that an operator needs to visually observe the process from original workpiece machining to rolled workpiece machining of an existing ring rolling machine limiting device, and defective products can be generated due to the fact that a ring rolling wheel cannot be withdrawn on time if the reaction is not timely, and the ring rolling machine limiting device comprises a connecting rod supporting shaft located on one side of a connecting rod, and a shaft of the connecting rod supporting shaft is perpendicular to a shaft of the connecting rod; the connecting rod is rotationally matched with the connecting rod supporting shaft; when the connecting rod rotates around the connecting rod supporting shaft, the distance between the connecting rod and the workpiece mandrel can be changed; the adjusting bolt is located on the side, away from the workpiece mandrel, of the connecting rod. The length of the adjusting bolt can be adjusted; further, the maximum distance between the connecting rod and the workpiece mandrel is changed; the grinding and expanding wheel, the rolled workpiece, the connecting rod and a coil of the relay QS1 can be sequentially connected in series to form a car withdrawing induction circuit; the car-withdrawing induction circuit is connected between the positive electrode and the negative electrode of the power supply.

Description

Technical Field

[0001] The utility model relates to a metal processing tool. Background Art

[0002] In the existing forging production line, the reaming machine limit device used in the ring rolling process of bearing forgings by the reaming machine is as Figure 4 shown. After welding the connecting rod and the sliding bushing, they are installed on the connecting rod support shaft. After adjusting the fine-tuning bolt on the machine tool, the operator moves the control handle in the forward direction, and the ring rolling wheel gradually moves downward, applying an external force to the outer wall of the original workpiece, so that the inner wall of the original workpiece contacts the mandrel to generate rolling deformation. When the operator observes that the deformation amount reaches the rolled workpiece 7 that meets the requirements of the drawing and contacts the connecting rod, the operator moves the control handle in the reverse direction, and the ring rolling wheel returns upward to complete the processing.

[0003] However, in the process of the existing reaming machine limit device for processing the original workpiece to the rolled workpiece, it requires the operator to visually observe. If the reaction is not timely and the ring rolling wheel fails to retract the vehicle on time, defective products will be produced. Moreover, the labor intensity of the operator is high, and the output of defective products will increase in the fatigue state. Summary of the Utility Model

[0004] The purpose of the utility model is to overcome the problem that in the process of the existing reaming machine limit device for processing the original workpiece to the rolled workpiece, it requires the operator to visually observe. If the reaction is not timely and the ring rolling wheel fails to retract the vehicle on time, defective products will be produced, and a reaming machine limit device is provided.

[0005] The reaming machine limit device of the utility model includes a connecting rod, a connecting rod support shaft, an adjusting bolt, a vehicle-retracting induction circuit, and a working circuit;

[0006] The connecting rod support shaft is located on one side of the connecting rod, and the axis of the connecting rod support shaft is perpendicular to the axis of the connecting rod;

[0007] The connecting rod is rotationally matched with the connecting rod support shaft; so that when the connecting rod rotates around the connecting rod support shaft, the distance from the workpiece mandrel can be changed;

[0008] The adjusting bolt is located on the side of the connecting rod away from the workpiece mandrel; so that when the adjusting bolt abuts against the connecting rod, the maximum distance between the connecting rod and the workpiece mandrel is limited;

[0009] The adjusting bolt can adjust its own length; thereby changing the maximum distance between the connecting rod and the workpiece mandrel;

[0010] The ring rolling wheel, the rolled workpiece, the connecting rod, and the coil of the relay QS1 can be sequentially connected in series to form a vehicle-retracting induction circuit; the vehicle-retracting induction circuit is connected between the positive and negative poles of the power supply;

[0011] The working circuit includes a start switch Q1, a relay ST1, a relay KA1, a relay KA2, a rotary expansion wheel working relay KT1, and a rotary expansion wheel reset relay KT2;

[0012] The start switch Q1, the normally closed contact of the relay ST1, and the coil of the relay KA1 are connected in series in turn and then connected between the positive and negative poles of the power supply;

[0013] The normally open contact of the relay QS1 and the coil of the relay ST1 are connected in series and then connected between the positive and negative poles of the power supply;

[0014] The normally open contact of the relay ST1 and the coil of the relay KA2 are connected in series and then connected between the positive and negative poles of the power supply;

[0015] The first normally open contact of the relay KA1 and the coil of the rotary expansion wheel working relay KT1 are connected in series and then connected between the positive and negative poles of the power supply;

[0016] The first normally open contact of the relay KA2 and the coil of the rotary expansion wheel reset relay KT2 are connected in series and then connected between the positive and negative poles of the power supply.

[0017] Furthermore, it also includes a bearing and a bearing rotating shaft;

[0018] The bearing is rotationally fitted to the connecting rod through the bearing rotating shaft, and the diameter of the bearing is larger than the width of the connecting rod;

[0019] The minimum distance from the workpiece mandrel to the side wall of the bearing is less than the minimum distance from the workpiece mandrel to the side wall of the connecting rod;

[0020] The rotary expansion wheel, the workpiece, the bearing, the connecting rod, and the coil of the relay QS1 can be connected in series in turn to form a reverse movement induction circuit.

[0021] Furthermore, a bearing position adjustment groove is provided on the connecting rod;

[0022] The bearing rotating shaft of the bearing is located in the bearing position adjustment groove;

[0023] The bearing rotating shaft of the bearing can move and be fixed in the bearing position adjustment groove; thereby changing the position of the bearing in the length direction of the connecting rod.

[0024] Furthermore, the working circuit also includes a travel switch QS2;

[0025] The triggering end of the travel switch QS2 is located at the original position of the rotary expansion wheel; it can detect whether the rotary expansion wheel is at the original position;

[0026] The normally open contact of the relay ST1, the normally closed contact of the travel switch QS2, and the coil of the relay KA2 are connected in series and then connected between the positive and negative poles of the power supply.

[0027] Further, the second normally open contact of the relay KA1 is connected in parallel with the start switch Q1; the second normally open contact of the relay KA2 is connected in parallel with the normally open contact of the relay ST1.

[0028] Further, the working circuit further includes an emergency stop button Q2;

[0029] The start switch Q1, the normally closed contact of the relay ST1, the normally closed contact of the emergency stop button Q2, and the coil of the relay KA1 are sequentially connected in series and then connected between the positive and negative poles of the power supply;

[0030] The normally open contact of the emergency stop button Q2 is connected in parallel with the normally open contact of the relay ST1.

[0031] Further, the relay ST1 is a time relay, and the delay setting of the relay ST1 is 0.5 s to 3 s.

[0032] The beneficial effects of the present utility model are as follows:

[0033] The reaming machine limit device of this embodiment realizes the automatic reverse function of the rolling wheel by adding a reverse vehicle induction circuit, eliminating the need for the operator to continuously observe the contacts and manually reverse the operation to control the start switch Q1, greatly reducing the generation of defective products and the labor intensity of the operator. Description of the Drawings

[0034] Figure 1 It is a front view matching structure diagram of the reaming machine limit device of this embodiment with the rolling wheel and the workpiece mandrel;

[0035] Wherein the dotted line represents the pressed rolling wheel and the rolled workpiece;

[0036] Figure 2 It is a side view matching structure diagram of the connecting rod, bearing, bearing rotating shaft and bearing nut in the reaming machine limit device of this embodiment;

[0037] Figure 3 It is a structure diagram of the working circuit in the reaming machine limit device of this embodiment;

[0038] Figure 4 It is a front view matching structure diagram of the existing reaming machine limit device with the rolling wheel and the workpiece mandrel. Specific Embodiments

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0041] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but it is not limited to the present invention. Specific Embodiment 1

[0043] The reaming machine limit device of this embodiment includes a connecting rod 1, a connecting rod support shaft 2, an adjusting bolt 3, a reverse car induction circuit, and a working circuit;

[0044] The connecting rod support shaft 2 is located on one side of the connecting rod 1, and the axis of the connecting rod support shaft 2 is perpendicular to the axis of the connecting rod 1;

[0045] The connecting rod 1 is rotationally matched with the connecting rod support shaft 2; so that when the connecting rod 1 rotates around the connecting rod support shaft 2, the distance from the workpiece mandrel 5 can be changed;

[0046] The adjusting bolt 3 is located on the side of the connecting rod 1 away from the workpiece mandrel 5; so that when the adjusting bolt 3 abuts against the connecting rod 1, the maximum distance between the connecting rod 1 and the workpiece mandrel 5 is limited;

[0047] The adjusting bolt 3 can adjust its own length; thereby changing the maximum distance between the connecting rod 1 and the workpiece mandrel 5;

[0048] The roller expander 6, the workpiece 7 after rolling, the connecting rod 1, and the coil of the relay QS1 can be sequentially connected in series to form a reverse car induction circuit; the reverse car induction circuit is connected between the positive and negative poles of the power supply;

[0049] The working circuit includes a start switch Q1, a relay ST1, a relay KA1, a relay KA2, a roller expander working relay KT1, and a roller expander reset relay KT2;

[0050] The start switch Q1, the normally closed contact of the relay ST1, and the coil of the relay KA1 are sequentially connected in series and then connected between the positive and negative poles of the power supply;

[0051] The normally open contact of the relay QS1 and the coil of the relay ST1 are connected in series and then connected between the positive and negative poles of the power supply;

[0052] The normally open contact of the relay ST1 and the coil of the relay KA2 are connected in series and then connected between the positive and negative poles of the power supply;

[0053] The first normally open contact of the relay KA1 and the coil of the roller expander working relay KT1 are connected in series and then connected between the positive and negative poles of the power supply;

[0054] The first normally open contact of the relay KA2 and the coil of the roller expander reset relay KT2 are connected in series and then connected between the positive and negative poles of the power supply.

[0055] Specifically, the reaming machine limit device of this embodiment is improved on the basis of the original reaming machine tool. The original reaming machine tool includes an expanding wheel 6 and a workpiece mandrel 5.

[0056] As Figures 1-2 shown, the expanding wheel 6 is located above the workpiece mandrel 5, and the connecting rod 1 is located below the workpiece mandrel 5.

[0057] The connecting rod 1 is fixed to a bushing 10 and sleeved on the connecting rod support shaft 2 through the bushing 10, so that the length direction of the connecting rod 1 is perpendicular to the central axis of the connecting rod support shaft 2 and can rotate around the connecting rod support shaft 2. In order to make the distance between the connecting rod 1 and the workpiece mandrel 5 change significantly when the connecting rod 1 rotates, the connecting rod support shaft 2 should be as close as possible to one end of the connecting rod 1, and the workpiece mandrel 5 should be as close as possible to the other end of the connecting rod 1 (however, in order for the workpiece 7 to have sufficient contact, the workpiece mandrel 5 should not be too close to the other end of the connecting rod 1).

[0058] The adjusting bolt 3 includes a nut and a mating screw. The nut is relatively fixed in position with respect to the workpiece mandrel 5, and the screw is in threaded engagement with the nut. The ability of the adjusting bolt 3 to adjust its own length means that the screw can adjust the length extending above the nut.

[0059] A wire mounting hole 4 can be machined at the end of the connecting rod 1 to connect the connecting rod 1 to the reverse movement induction circuit. Moreover, the expanding wheel 6, the workpiece 7, and the connecting rod 1 are all made of metal and have the property of conductivity. When the workpiece 7 is reamed to meet the requirements, a reamed workpiece 7 is formed. The reamed workpiece 7 can electrically connect the expanding wheel 6, the reamed workpiece 7, and the connecting rod 1 to the coil of the relay QS1 to form a conductive circuit, that is, the reverse movement induction circuit. When the reverse movement induction circuit is turned on, the coil of the relay QS1 is energized, and then Figure 3 the normally open contact of the relay QS1 is triggered to close.

[0060] To ensure the formation of the above reverse movement induction circuit, the connecting rod 1 and the connecting rod support shaft 2 should be insulated. An insulating cap is installed on the adjusting bolt 3 for insulation.

[0061] As Figures 1-3 shown, the specific operation process is as follows:

[0062] Adjust the length of the adjusting bolt 3 so that when the connecting rod 1 abuts against the adjusting bolt 3, the requirements for adjusting the processing range of the workpiece 7 are met.

[0063] The workpiece 7 is sleeved outside the workpiece mandrel 5 through its own hole set. The operator closes the start switch Q1, the coil of the relay KA1 is energized, the first normally open contact of the relay KA1 is closed, the coil of the rotary expansion wheel working relay KT1 is energized, and then the power mechanism of the rotary expansion wheel 6 is controlled to press down the rotary expansion wheel 6 (the contact of the rotary expansion wheel working relay KT1 connected in the power mechanism is closed). The gradually downward movement of the rotary expansion wheel 6 applies an external force to the outer wall of the workpiece 7, causing the inner wall of the workpiece 7 to contact the workpiece mandrel 5 and generate rolling deformation, and the inner hole gradually expands until the rotary expansion is completed. The workpiece 7 after the rotary expansion contacts the connecting rod 1 to form an electrical connection (retracting vehicle induction circuit).

[0064] The normally open contact of the trigger relay QS1 is closed, the coil of the relay ST1 is energized, the normally open contact of the relay ST1 is closed, the coil of the relay KA2 is energized, the first normally open contact of the relay KA2 is closed, the coil of the rotary expansion wheel reset relay KT2 is energized, and then the power mechanism of the rotary expansion wheel 6 is controlled to lift the rotary expansion wheel 6 (the contact of the rotary expansion wheel working relay KT2 connected in the power mechanism is closed); when the coil of the relay ST1 is energized, the normally closed contact of the relay ST1 is opened, the coil of the relay KA1 is de-energized, the first normally open contact of the relay KA1 is opened, the coil of the rotary expansion wheel working relay KT1 is de-energized, and the power mechanism of the rotary expansion wheel 6 stops the downward pressing operation to avoid conflicting with the operation of lifting the rotary expansion wheel 6.

[0065] The hole expanding machine limit device of this embodiment realizes automatic vehicle retraction, and does not require the operator to always observe the contacts and manually reverse the operation control handle (start switch Q1). It greatly reduces the generation of defective products and the labor intensity of the operator. Specific Embodiment 2

[0067] This embodiment is a further description of Embodiment 1. In this embodiment, it further includes a bearing 8 and a bearing rotating shaft 11;

[0068] The bearing 8 is rotationally fitted to the connecting rod 1 through the bearing rotating shaft 11, and the diameter of the bearing 8 is greater than the width of the connecting rod 1;

[0069] The minimum distance from the workpiece mandrel 5 to the side wall of the bearing 8 is less than the minimum distance from the workpiece mandrel 5 to the side wall of the connecting rod 1;

[0070] The rotary expansion wheel 6, the workpiece 7, the bearing 8, the connecting rod 1 and the coil of the relay QS1 can be sequentially connected in series to form a retracting vehicle induction circuit.

[0071] Other technical features of this embodiment are exactly the same as those of Embodiment 1.

[0072] Specifically, the existing limit device of the hole reamer can only be dismantled and scrapped when the connecting rod is worn to a certain extent due to the long-term contact and wear between the connecting rod and the rotating workpiece during use, resulting in a short service life of the connecting rod and increased processing costs. In addition, since the connecting rod is supported by ordinary steel parts, the contact point will form an arc surface after long-term wear. When processing the same batch of products, the processed workpiece will exceed the process requirement range due to long-term contact and wear. When it is found that it is close to the process requirement limit, the machine needs to be stopped and the line needs to be adjusted to fine-tune the bolts, resulting in a large number of measurements per shift, making the processing process too cumbersome.

[0073] In this embodiment, a bearing 8 is additionally provided, and the bearing 8 is rotatably engaged with the connecting rod 1 via a bearing rotating shaft 11. The bearing 8 should be located below the workpiece core shaft 5 as far as possible.

[0074] In the reamer limit device of this embodiment, the bearing 8 replaces the rod of the connecting rod 1 to contact the workpiece 7, so the formation of the retraction induction circuit requires the addition of the bearing 8. When the workpiece 7 after rolling is in contact (electrically connected) with the bearing 8, the retraction induction circuit is formed. When the retraction induction circuit is turned on, the coil of the relay QS1 is energized, thereby triggering the normally open contact of the relay QS1 to close.

[0075] The hardness of the bearing 8 can be around 60-63, and the wear resistance is good. The contact between the rolled workpiece 7 and the bearing 8 is changed from the original pure friction with the connecting rod 1 to the rotational friction, and the force is small. It can be used continuously if the bearing 8 is not damaged.

[0076] When adding the bearing 8 , the requirement for adjusting the processing range of the workpiece 7 needs to take into account the size of the bearing 8 . Specific implementation method three

[0078] This embodiment is a further explanation of the second embodiment. In this embodiment, a bearing position adjustment groove 9 is provided on the connecting rod 1;

[0079] The bearing rotation axis 11 of the bearing 8 is located in the bearing position adjustment groove 9;

[0080] The bearing rotating shaft 11 of the bearing 8 can be moved and fixed in the bearing position adjustment groove 9 , thereby changing the position of the bearing 8 in the length direction of the connecting rod 1 .

[0081] The other technical features of this embodiment are exactly the same as those of the second embodiment.

[0082] Specifically, since the existing reamer limit device is restricted by the fine-tuning bolt and has no space for downward adjustment, the tangent point between the connecting rod and the rolled workpiece changes little when the fine-tuning bolt is adjusted. When the outer diameter span of the rolled product is large (such as exceeding 30mm), the entire connecting rod needs to be disassembled and replaced with connecting rods of different lengths. This requires the production of multiple sets of connecting rods and matching sliding sleeves, which increases the cost of spare parts and the time cost of switching.

[0083] In this embodiment, a bearing position adjustment groove 9 is added. The bearing position adjustment groove 9 is a long groove. For the convenience of calculating the adjustment dimensions, the length direction of the bearing position adjustment groove 9 should be consistent with the length direction of the connecting rod 1. The bearing 8 moves along the length direction of the bearing position adjustment groove 9 through the bearing rotating shaft 11. The bearing rotating shaft 11 is provided with threads, and a bearing nut 12 is arranged on the side surface of the bearing position adjustment groove 9 far from the bearing 8 to be in threaded cooperation with the bearing rotating shaft 11, so as to lock the bearing rotating shaft 11 on the connecting rod 1. By adjusting the position of the bearing 8 at the bearing position adjustment groove 9, the processing range of the workpiece 7 is adjusted. The processing range is increased, from the original maximum processing of 120 mm to 160 mm.

[0084] The bearing rotating shaft 11 can be rotationally matched with the bearing 8 through a ball bearing, and a limiting component fixed to the bearing rotating shaft 11 can also be arranged on the side surface of the bearing position adjustment groove 9 close to the bearing 8. The size of the limiting component is larger than that of the bearing position adjustment groove 9, so as to lock the bearing rotating shaft 11 on the connecting rod 1 in cooperation with the bearing nut 12 to prevent squeezing the bearing 8 and making it difficult for the bearing 8 to rotate.

[0085] The position-limiting device of the reaming machine in this embodiment does not need to frequently adjust the adjusting bolt 3 to change the position of the connecting rod 1. Its position after one-time installation does not affect the switching of products of different models. It can be used continuously without disassembly after one-time installation, and it is also relatively convenient to replace the damaged bearing 8. Specific Embodiment Four

[0087] This embodiment is a further description of Embodiment One, Two or Three. In this embodiment, the working circuit further includes a travel switch QS2;

[0088] The triggering end of the travel switch QS2 is located at the original position of the sizing wheel 6; it can detect whether the sizing wheel 6 is at the original position;

[0089] The normally open contact of the relay ST1, the normally closed contact of the travel switch QS2 and the coil of the relay KA2 are connected in series between the positive and negative poles of the power supply.

[0090] Other technical features of this embodiment are exactly the same as those of Embodiment One, Two or Three.

[0091] Specifically, the travel switch QS2 is used to judge whether the sizing wheel 6 is reset and trigger the operation of closing the power mechanism of the sizing wheel 6 to lift the sizing wheel 6.

[0092] When the rolling and expanding wheel 6 resets to its original position, it presses the triggering end of the extrusion travel switch QS2. The normally closed contact of the travel switch QS2 disconnects, the coil of the relay KA2 loses power, the first normally open contact of the relay KA2 disconnects, and the coil of the rolling and expanding wheel reset relay KT2 loses power, thereby stopping the upward lifting of the rolling and expanding wheel 6. Specific Embodiment 4

[0094] This embodiment is a further description of Embodiment 5. In this embodiment, the second normally open contact of the relay KA1 is connected in parallel with the start switch Q1; the second normally open contact of the relay KA2 is connected in parallel with the normally open contact of the relay ST1.

[0095] The other technical features of this embodiment are exactly the same as those of Embodiment 5.

[0096] Specifically, the second normally open contacts of the relay KA1 and the relay KA2 are respectively used for the self-locking of the relay KA1. Specific Embodiment 6

[0098] This embodiment is a further description of Embodiment 1, 2 or 5. In this embodiment, the working circuit further includes an emergency stop button Q2;

[0099] The start switch Q1, the normally closed contact of the relay ST1, the normally closed contact of the emergency stop button Q2, and the coil of the relay KA1 are connected in series in turn between the positive and negative poles of the power supply;

[0100] The normally open contact of the emergency stop button Q2 is connected in parallel with the normally open contact of the relay ST1.

[0101] The other technical features of this embodiment are exactly the same as those of Embodiment 1, 2 or 5.

[0102] Specifically, the emergency stop button Q2 is used for the stop operation when the rolling and expanding wheel 6 presses down. When an emergency stop is required, press the emergency stop button Q2, then the normally closed contact of the emergency stop button Q2 disconnects, the coil of the rolling and expanding wheel working relay KT1 loses power, and the power mechanism of the rolling and expanding wheel 6 stops the pressing-down operation. At the same time, the normally open contact of the emergency stop button Q2 closes, the coil of the rolling and expanding wheel reset relay KT2 gets power, and then controls the power mechanism of the rolling and expanding wheel 6 to lift the rolling and expanding wheel 6 to its original position. Specific Embodiment 7

[0104] This embodiment is a further description of Embodiment 6. In this embodiment, the relay ST1 is a time relay, and the delay setting of the relay ST1 is 0.5 s to 3 s.

[0105] The other technical features of this embodiment are exactly the same as those of Embodiment 6.

[0106] Specifically, a time relay is used to control the contact duration between the bearing 8 and the workpiece 7 completed by the rolling and scraping, and the vehicle is reversed after the contact duration reaches the required dimensional range of the workpiece 7, which greatly reduces the generation of defective products and the labor intensity of the operator.

[0107] Although the present invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should thus be understood that numerous modifications may be made to the exemplary embodiments, and other arrangements may be designed, without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that the different dependent claims and features herein may be combined in a manner different from that described in the original claims. It should also be understood that the features described in connection with a separate embodiment may be used in other embodiments.

Claims

1. The hole expander limit device is characterized by: It comprises a connecting rod (1), a connecting rod support shaft (2), an adjusting bolt (3), a vehicle reversing sensing circuit and a working circuit; The connecting rod support shaft (2) is located on one side of the connecting rod (1), and the axis of the connecting rod support shaft (2) is perpendicular to the axis of the connecting rod (1); The connecting rod (1) is rotatably matched with the connecting rod support shaft (2), so that when the connecting rod (1) rotates around the connecting rod support shaft (2), the distance from the workpiece core shaft (5) can be changed; The adjusting bolt (3) is located on a side of the connecting rod (1) away from the workpiece core shaft (5); when the adjusting bolt (3) abuts against the connecting rod (1), the maximum distance between the connecting rod (1) and the workpiece core shaft (5) is limited; The adjusting bolt (3) is capable of adjusting its own length, thereby changing the maximum distance between the connecting rod (1) and the workpiece core shaft (5); The rolling wheel (6), the rolled workpiece (7), the connecting rod (1) and the coil of the relay QS1 can be connected in series in sequence to form a retracting induction circuit; the retracting induction circuit is connected between the positive and negative electrodes of the power supply; The working circuit includes a starting switch Q1, a relay ST1, a relay KA1, a relay KA2, a rolling wheel working relay KT1 and a rolling wheel reset relay KT2; The start switch Q1, the normally closed contact of the relay ST1, and the coil of the relay KA1 are connected in series in sequence and then connected between the positive and negative poles of the power supply; The normally open contact of relay QS1 and the coil of relay ST1 are connected in series and connected between the positive and negative poles of the power supply; The normally open contact of relay ST1 and the coil of relay KA2 are connected in series and connected between the positive and negative poles of the power supply; The first normally open contact of relay KA1 and the coil of rolling wheel working relay KT1 are connected in series and then connected between the positive and negative electrodes of the power supply; The first normally open contact of relay KA2 and the coil of rolling wheel reset relay KT2 are connected in series and then connected between the positive and negative electrodes of the power supply.

2. The hole expansion machine limiting device according to claim 1, characterized in that: It also includes a bearing (8) and a bearing rotating shaft (11); The bearing (8) is rotationally matched with the connecting rod (1) via a bearing rotating shaft (11), and the diameter of the bearing (8) is greater than the width of the connecting rod (1); The minimum distance from the workpiece core shaft (5) to the side wall of the bearing (8) is smaller than the minimum distance from the workpiece core shaft (5) to the side wall of the connecting rod (1); The rolling wheel (6), the workpiece (7), the bearing (8), the connecting rod (1) and the coil of the relay QS1 can be sequentially connected in series to form a reversing induction circuit.

3. The hole expansion machine limiting device according to claim 2, characterized in that: The connecting rod (1) is provided with a bearing position adjustment groove (9); The bearing rotation axis (11) of the bearing (8) is located in the bearing position adjustment groove (9); The bearing rotating shaft (11) of the bearing (8) can be moved and fixed in the bearing position adjustment groove (9), thereby changing the position of the bearing (8) in the length direction of the connecting rod (1).

4. The hole expansion machine limiting device according to claim 1, 2 or 3, characterized in that: The working circuit also includes a travel switch QS2; The trigger end of the travel switch QS2 is located at the original position of the rolling wheel (6); and can detect whether the rolling wheel (6) is located at the original position; The normally open contact of the relay ST1, the normally closed contact of the travel switch QS2 and the coil of the relay KA2 are connected in series and then connected between the positive and negative electrodes of the power supply.

5. The hole expansion machine limiting device according to claim 4, characterized in that: The second normally open contact of relay KA1 is connected in parallel with the start switch Q1; the second normally open contact of relay KA2 is connected in parallel with the normally open contact of relay ST1.

6. The hole expander limiting device according to claim 1, 2 or 5, characterized in that: The working circuit also includes an emergency stop button Q2; The start switch Q1, the normally closed contact of the relay ST1, the normally closed contact of the emergency stop button Q2, and the coil of the relay KA1 are connected in series in sequence and then connected between the positive and negative poles of the power supply; The normally open contact of the emergency stop button Q2 is connected in parallel with the normally open contact of the relay ST1.

7. The hole expansion machine limiting device according to claim 6, characterized in that: Relay ST1 is a time relay, and the delay of relay ST1 is set to 0.5s~3s.

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