JP7579501B2 - Projection nut supply rod device - Google Patents

Description

The present invention relates to a projection nut supply rod device that reduces injury to a worker when a dangerous situation occurs, such as when the worker's hand is caught between the tip of the projection nut supply rod and the guide pin of an electric resistance welding electrode.

Japanese Patent Application Laid-Open No. 2002-172470 describes a technique for stopping the advancement of the supply rod when a dangerous situation occurs in which an operator's hand is caught between the tip of the supply rod of the projection nut and the guide pin of the electric resistance welding electrode.

JP 2002-172470 A

The worker's hand includes the back of the hand and the wrist, but since the main focus of the present invention is to protect the fingers, the reference to the worker's hand in the following description should be read as the worker's fingers.
The above-mentioned Patent Document 1 describes that the advancement of the supply rod is stopped when the worker's hand is pinched. However, no technical consideration is given to reducing the pinching force acting on the worker's hand. That is, FIG. 6 of Patent Document 1 shows a state in which the worker's finger is pinched between the tip of the supply rod and the guide pin of the electric resistance welding electrode. On the other hand, there is no description of the relationship between the central axial length of the spring chamber described in FIG. 1 of the same document and the thickness of the worker's finger in FIG. 6. Furthermore, there is no description of the properties of the compression coil spring arranged in the spring chamber.

The present invention has been provided to solve the above-mentioned problems, and has an object to reduce the clamping force acting on a worker's hand when the worker's hand is pinched between the tip of a supply rod of a projection nut and a guide pin of an electric resistance welding electrode.

The invention described in claim 1 is
In a projection nut that is stopped at a predetermined position, a small-diameter guide rod of a supply rod is pierced in a skewer-like manner through a screw hole of the projection nut, and the projection nut is supplied to an electrode for electric resistance welding,
The supply rod is accommodated in an outer cylinder in a state in which it can advance and retreat, and is composed of a tubular large-diameter rod having a slide hole formed therein, and the small-diameter guide rod inserted into the slide hole in a state in which it can advance and retreat,
The finger of the operator that is pinched between the small diameter guide rod and the electrode guide pin is to be protected.
a sensor is provided to detect a relative displacement of the small diameter guide rod in a retreating direction relative to the large diameter rod when an operator's finger is pinched between the small diameter guide rod and the electrode guide pin during the advancement of the supply rod,
The large diameter rod is provided with a long hole having a lower end surface in a direction of a central axis of the supply rod,
a projection fixed to the small diameter guide rod and detected by the sensor is disposed in a state of protruding outward from the long hole;
a long hole having a shape and dimensions substantially the same as those of the long hole provided in the large diameter rod is formed in the outer cylinder;
The protrusion to be detected is configured to move forward and backward within the long hole provided in the outer cylinder,
The welding electrode is stopped from advancing in response to a signal from the sensor.
A spring chamber is formed between an end of the small diameter guide rod in the slide hole and an inner end surface of the slide hole,
A compression coil spring is disposed in the spring chamber to impart tension to the small diameter guide rod in the pushing direction,
The distance in the central axis direction of the spring chamber is set to be 3 times or more and less than 5 times the pinch danger distance, which is set when the operator's finger is pinched between the small diameter guide rod and the electrode guide pin, thereby reducing the spring reaction force on the operator's finger and avoiding insufficient pushing force of the compression coil spring for the small diameter guide rod,
This is a projection nut supply rod device, characterized in that the maximum protrusion length of the small diameter guide rod relative to the large diameter rod is set by configuring the detection protrusion to be pressed against the lower end surface of the long hole provided in the large diameter rod by the tension of the compression coil spring.

The supply rod consists of a tubular large diameter rod with a slide hole formed therein, and a small diameter guide rod inserted into the slide hole in a state where it can advance and retreat. The distance in the central axial direction of the spring chamber formed between the end of the small diameter guide rod in the slide hole and the inner end face of the slide hole is set to be at least three times the pinch danger distance where an operator's hand would be pinched between the small diameter guide rod and the electrode guide pin, and a compression coil spring is arranged in the spring chamber to apply tension in the extrusion direction to the small diameter guide rod.

Since the distance in the central axis direction of the spring chamber is set to be three times or more the pinch danger distance where the worker's hand is pinched between the small diameter guide rod and the electrode guide pin, the amount of deflection of the compression coil spring arranged in the spring chamber can be set to a small ratio to the distance in the central axis direction of the spring chamber before the start of deflection. The wire diameter of the compression coil spring can be made thin, and the length of the compression coil spring can be made sufficiently long. By reducing the rate of deflection and selecting the length of the compression coil spring, the worker's hand can be pinched between the small diameter guide rod and the electrode guide pin in the initial stage of deflection deformation, and the pinching force on the worker's hand can be reduced, preventing injury to the worker or making the injury extremely minor if any.

In this way, a compression coil spring with a small spring constant can be utilized. In other words, if a compression coil spring is inserted into a spring chamber with a short distance in the central axis direction, the compression length of the compression coil spring becomes significantly larger than the value before compression, and the elastic reaction force becomes larger accordingly, which increases the pressure acting on the operator's hand.

In the accidents where the worker's hand is pinched as described above, the fingertip is usually pinched. It is reasonable to recognize that the distance between the small diameter guide rod and the electrode guide pin when the finger is pinched, that is, the pinch danger distance, which corresponds to the thickness of the finger, is about 16 to 19 mm for male workers and about 13 to 16 mm for female workers. Under such dimensions, the distance in the central axis direction of the spring chamber is set to be three times or more the pinch danger distance when the worker's hand is pinched between the small diameter guide rod and the electrode guide pin. Therefore, the shape of the spring chamber space is elongated, and when the finger is pinched as described above, the deflection length of the compression coil spring can be made smaller than the length before deflection, and the finger can be pinched at the initial stage of deformation of the compression coil spring, so that the elastic pressure force on the finger can be reduced.

The present invention is a supply rod device for a projection nut, but it can also be realized as a method for controlling the operation of the supply rod, using the pinching of an operator's hand as a trigger signal.

1 is a side view of the entire device and cross-sectional views of each part. FIG. 4 is a cross-sectional view showing a displaced state of the guide rod. FIG. 2 is a side view taken from the direction of the arrow (3) in FIG. 4 is a cross-sectional view showing a stopper structure of a supply rod. FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a projection nut supply rod device according to the present invention will be described.

1 to 4 show an embodiment of the present invention.

First, the projection nut will be described.

In the following description, the projection nut may be simply referred to as a nut.

As shown in Fig. 2(A) and other figures, the iron projection nut 1 has a screw hole 3 drilled in the center of a square nut body 2, and welding projections 4 provided at the four corners of one side. The dimensions of each part of the nut 1 in this embodiment are: one side of the nut body 2 is 13 mm, the inside diameter of the screw hole 3 is 6 mm, and the thickness of the nut body 2 is 6 mm.

Next, the supply rod will be described.

Fig. 1(B) shows the supply rod 5 alone. The symbol O-O indicates the central axis of the supply rod 5, and the entire device is tilted so that this axis is tilted. The supply rod 5 is mainly composed of a large diameter rod 6 and a small diameter guide rod 7 with a circular cross section. The large diameter rod 6 is composed of a tubular member with a circular cross section slide hole 8 formed in the center, and has a square cross section as shown in Fig. 1(E). By making it have such a square cross section, the large diameter rod 6 is prevented from rotating.

The small diameter guide rod 7 is made of a solid rod-shaped member with a circular cross section, and is inserted into the sliding hole 8 in a state in which it can advance and retreat. The insertion here is such that there is no gap between the inner surface of the sliding hole 8 and the outer circumferential surface of the small diameter guide rod 7, and there is no rattling sensation due to the gap when the small diameter guide rod 7 is moved in the diameter direction. In Fig. 1 (B) , the entire area in which the small diameter guide rod 7 is inserted is slidable without any gaps, but such slidable areas may be partially arranged. In other words, this is the case where the inner diameter of the sliding hole 8 is partially enlarged.

1(B) shows a normal operating state in which the supply rod 5 has advanced and the tip of the small diameter guide rod 7 is stopped just before the electrode guide pin 10 of the fixed electrode 9. The relative position of the small diameter guide rod 7 with respect to the large diameter rod 6 is such that the small diameter guide rod 7 protrudes most from the large diameter rod 6. A steel sheet part 11 is placed on the fixed electrode 9, and the electrode guide pin 10 penetrates a pilot hole 12 in the steel sheet part 11 and protrudes.

The fixed electrode 9 is an electrode for electric resistance welding, and the mating movable electrode 15 is shown in Fig. 1(A) and Fig. 2(A). The nut 1 is welded to the steel plate part 11 by the advancement of the movable electrode and the passage of a welding current.

Next, the spring chamber will be described.

A spring chamber 16 is formed between an end face 13 of the small diameter guide rod 7 in the sliding hole 8 and an inner end face 14 of the sliding hole 8. A compression coil spring 17 is disposed in the spring chamber 16, and its tension acts in a direction to push the small diameter guide rod 7 out.

Next, the temporary stopping chamber will be described.

The supply rod 5 is housed in an outer cylinder 18 in a state where it can move forward and backward, and a square hole 19 is provided in a part of the inside of the outer cylinder 18 through which the large diameter rod 6 slides. A nut supply pipe 20 extending from a parts feeder (not shown) has a rectangular cross section so that a square nut 1 can pass through. The nut supply pipe 20 is welded to the end of the outer cylinder 18. In the figure, the welded part is shown as filled in black. As is clear from FIG. 1(D), a temporary stop chamber 21 is formed at the intersection of the outer cylinder 18 and the nut supply pipe 20. Reference numeral 22 denotes an outlet opening for the supply rod 5 and the nut 1.

The thickness of the outer cylinder 18 is set to a large dimension in order to increase the strength and rigidity of the outer cylinder 18 itself and improve the mounting stability of the device. This outer cylinder 18 is fixed to a stationary member 29 such as a machine frame to which the device is mounted.

When the nut 1 advances in the longitudinal direction of the nut supply pipe 20 and enters the temporary locking chamber 21, it is received by the stop guide plate 23, and the nut 1 is positioned . That is, as shown in Fig. 1 (D), the screw hole 3 of the nut 1 and the small diameter guide rod 7 are coaxial. A flat surface 24 is formed near the lower end of the outer tube 18, and the stop guide plate 23 is pressed against it. The stop guide plate 23 is pressed against the flat surface 24 and fixed by a fixing bolt 26 screwed into a support piece 25 fixed to the outer tube 18. A permanent magnet 27 is embedded in the stop guide plate 23, and the nut 1 is drawn into the temporary locking chamber 21 by its magnetic attraction.

The tip of the nut supply pipe 20 is bifurcated, and a stop guide plate 23 is abutted against the tip of the bifurcated part to form the space of the temporary stop chamber 21. A through hole 28 is formed in the ceiling side of the nut supply pipe 20, and the large diameter rod 6 passes through this hole.

Next, the means for advancing and retracting the supply rod will be described.

As the means for advancing and retracting the supply rod 5, various means can be used, such as an air cylinder, an electric motor with forward and backward movement output, a rack and pinion mechanism, etc. Here, an air cylinder is used.

An air cylinder 30 is connected to the outer cylinder 18, and a piston rod 31 of the air cylinder 30 is connected to the large diameter rod 6. The dimensions of each part are selected so that when the air cylinder 30 is fully retracted, the tip of the small diameter guide rod 7 is slightly retracted from the temporary stop chamber 21, as shown in FIG. 1(D).

Next, a structure for restricting the advancement length of the small diameter guide rod will be described.

An oblong hole 32 is formed in the large diameter rod 6 in the direction of the central axis O-O. A detectable projection 33 fixed to the small diameter guide rod 7 by a bolt or the like protrudes outward from the oblong hole 32. The projection 33 has a fixed portion 34 and a detectable portion 35 formed in an L-shape, the fixed portion 34 is fixed to the small diameter guide rod 7 by a bolt, and the detectable portion 35 protrudes from the oblong hole 32 as described above.

An elongated hole 37 is formed in the outer cylinder 18 in the direction of the central axis O-O. The elongated hole 37 is set to have approximately the same shape and dimensions as the elongated hole 32 formed in the large diameter rod 6. As shown in Fig. 1(C) , the detected part 35 is disposed in the elongated hole 37 without protruding outward from the elongated hole 37, and is capable of advancing and retreating within the elongated hole 37 in the direction of the central axis O-O.

Since the tension of the compression coil spring 17 acts on the small diameter guide rod 7, the projection 33 fixed to the small diameter guide rod 7 is pressed against the lower end surface 38 (see FIG. 3) of the long hole 32, and the maximum protruding length of the small diameter guide rod 7 relative to the large diameter rod 6 is set. The distance in the direction of the central axis O-O of the spring chamber 16 at this time is the maximum distance. The lower end surface 36 of the large diameter rod 6 is used as the pushing surface of the nut 1 waiting in the temporary locking chamber 21.

Next, the sensor will be described.

The sensor indicated by the reference numeral 40 transmits a detection signal when the detected part 35 stops at the normal position as shown in Fig. 1(C). If the long holes 37 and 32 are open and exposed, iron filings or other debris may enter the long holes and cause problems with the sliding action. To solve this problem, a plate-shaped cover member 41 that closes the long hole 37 is attached by bolts or the like. Various types of sensor 40 can be used, but a capacitance type proximity sensor is suitable, for example.

In order to accurately detect the detected part 35 that has stopped in the normal position, the relative positions of the sensor 40 and the detected part 35 are set correctly. To achieve this, the sensor 40 is arranged to be in the correct position when the cover member 41 is attached in a predetermined position. Here, as shown enlarged in Fig. 1(E), a recess 42 is formed in the cover member 41, and the sensor 40 is fitted and attached therein. Reference numeral 43 denotes a signal line for the sensor 40.

1C, when the relative positions of the sensor 40 and the detected portion 35 are correctly set, the movable electrode 15 advances at a predetermined time in response to a signal from the sensor 40. Such an operation can be performed by a general control system.

The above control system will be described based on this embodiment. For example, when an operator inputs a start signal to a control device composed of a simple computer device or a sequence circuit, the air switching valve operates with a command signal from the control device, and the supply rod 5 advances by the air cylinder 30. When the nut 1 through which the small diameter guide rod 7 penetrates slides down the small diameter guide rod 7 and is correctly supplied to the electrode guide pin 10 by this advancement, the protrusion 33 hits the lower end surface 38 of the long hole 32 at the same time, the advancement of the supply rod 5 stops, and the sensor 40 and the detected part 35 are in a positional relationship facing each other, and the relative positions of the two are correctly set. At this time, a signal transmitted from the sensor 40 is transmitted from the control device to permit the movable electrode 15 to advance, and the nut welding to the steel plate part 11 is completed. The operation of the device centered on the control device as described above is also described in the above-mentioned Patent Document 1.

Next, the central axial distance of the spring chamber will be described.

As shown in Fig. 1B, 1C and 2B, when the supply rod 5 advances normally, the distance in the central axis direction of the spring chamber 16 is set to a maximum length L1. As shown in Fig. 2A, due to the carelessness of the operator, the operator's hand may be pinched between the small diameter guide rod 7 and the electrode guide pin 10, and usually the operator's finger is pinched. In such a case, the stopped small diameter guide rod 7 is relatively pushed backward in the direction of the central axis O-O by the advancement of the large diameter rod 6. At this time, the small diameter guide rod 7 advances into the spring chamber 16 while compressing the compression coil spring 17. The length of this pushing is the pinch danger distance L2, which corresponds to the distance between the tip of the small diameter guide rod 7 and the electrode guide pin 10 when the finger is pinched, i.e., the thickness of the finger.

The distance between the small diameter guide rod 7 and the electrode guide pin 10, i.e., the pinch danger distance L2, which corresponds to the thickness of a finger, is appropriately recognized as being about 16 to 19 mm for male workers and about 13 to 16 mm for female workers, as described above. In other words, the pinch danger distance L2 is determined based on the dimensions listed here. Here, L2 is set to 19 mm, which is the thickness of the finger of an elastic worker.

The distance L1 of the spring chamber 16 in the direction of the central axis O--O is set to be three times or more the pinch danger distance L2 when the operator's hand is pinched between the small diameter guide rod 7 and the electrode guide pin 10. In this case, the pinch danger distance L2 is 66.5 mm, which corresponds to 3.5 times.

By setting the distance to three or more times as large as above, the spring reaction force does not become large when the distance L2 is short, i.e., when the compression length of the compression coil spring 17 is short and the spring reaction force is small, so that the worker will only experience mild pain or injury, which is preferable in terms of protecting the worker.

If the distance L1 is less than three times the distance L2, the distance L1 becomes too short, and the elastic reaction force of the compression coil spring 17 acting on the finger becomes large, resulting in insufficient protection of the operator. If the distance L1 is five times the distance L2 or more, this is favorable in terms of reducing the spring reaction force on the finger, but there is a risk that the pushing force of the compression coil spring 17 for the small diameter guide rod 7 will be insufficient, and this is also undesirable in terms of making the supply rod 5 and the entire device compact.

FIG. 1E is a cross-sectional view taken along line EE of FIG. 1C, but is also a cross-sectional view taken along line EE of FIG.

Next, the operation of the device will be described.

Before the device starts operating, the elastic force of the compression coil spring 17 presses the protrusion 33 against the lower end surface 38 of the long hole 32, and the air cylinder 30 is moved to its rearmost position, so that the tip of the small diameter guide rod 7 is positioned retracted from the temporary stop chamber 21, as shown in FIG. 1(D).

When the supply rod 5 advances due to the advancing operation of the air cylinder 30, the small diameter guide rod 7 advances into the threaded hole 3 of the nut 1 waiting in the temporary stop chamber 21, forming a skewer shape, and as it advances further, the pushing surface 36 presses the upper surface of the nut 1, causing the nut 1 to be sent out while rubbing against the stop guide plate 23, and the nut 1 slides down the small diameter guide rod 7. When the advance of the supply rod 5 stops just before the electrode guide pin 10, the nut 1 is transferred onto the steel plate part 11 by the force of inertia. At this time, the electrode guide pin 10 advances relatively into the threaded hole 3, and the positioning of the nut 1 is completed.

When the nut supply is completed as described above, the projection 33 is pressed against the lower end surface 38 of the long hole 32, so that the detected portion 35 faces the sensor 40 correctly, and the signal transmitted from the sensor 40 at this time causes the movable electrode 15 to advance. Before the movable electrode 15 advances, the supply rod 5 has retracted in advance, so that the movable electrode 15 can advance and apply pressure to the nut 1. Thereafter, a welding current is applied to complete the electric resistance welding.

2A, when the operator's finger is pinched between the small guide rod 7 and the electrode guide pin 10, the small guide rod 7 is pushed back into the spring chamber 16 while relatively compressing the compression coil spring 17. This push-back displacement causes the detected part 35 to stop at a position shifted from the sensor 40, so the sensor 40 does not transmit an electrode advance permission signal, the movable electrode 15 does not advance, and there is no risk of the finger being pinched between the electrodes.

In the above operation, as shown in Fig. 1(C), it is necessary to stop the tip of the small diameter guide rod 7 correctly just before the electrode guide pin 10. Various structures can be adopted for this purpose, one example of which is the structure shown in Fig. 4. Here, a flange 44 fixed to the end of the large diameter rod 6 is abutted against a stopper surface 45 to stop the rod. The flange 44 is fixed between the large diameter rod 6 and the piston rod 31. Therefore, when the supply rod 5 is advanced by the air cylinder 30, the flange 44 is received by the stopper surface 45, and the tip of the small diameter guide rod 7 stops at the correct position.

The effects of the embodiment described above are as follows.

The supply rod 5 is composed of a tubular large diameter rod 6 in which a slide hole 8 is formed, and a small diameter guide rod 7 inserted into the slide hole 8 in a state in which it can advance and retreat. A spring chamber 16 is formed between the end (end face 13) of the small diameter guide rod 7 in the slide hole 8 and the inner end face 14 of the slide hole 8, and the distance L1 in the direction of the central axis O-O of the spring chamber 16 is set to be three times or more the pinch danger distance L2 in which an operator's hand is pinched between the small diameter guide rod 7 and the electrode guide pin 10. A compression coil spring 17 is disposed in the spring chamber 16 to apply tension in the extrusion direction to the small diameter guide rod 7.

Since the distance L1 in the direction of the central axis O-O of the spring chamber 16 is set to be three times or more the pinch danger distance L2 where the worker's hand is pinched between the small diameter guide rod 7 and the electrode guide pin 10, the amount of deflection of the compression coil spring 17 arranged in the spring chamber 16 can be set to a small ratio to the distance L1 in the direction of the central axis O-O of the spring chamber 16 before the start of deflection. The wire diameter of the compression coil spring 17 can be made thin, and the length of the compression coil spring 17 can be made sufficiently long. By reducing the rate of deflection and selecting the length of the compression coil spring 17, the worker's hand can be pinched between the small diameter guide rod 7 and the electrode guide pin 10 in the initial stage of deflection deformation, and the pinching force on the worker's hand can be reduced, preventing injury to the worker or making the injury extremely minor if any.

In this way, it is possible to utilize the compression coil spring 17 with a small spring constant. In other words, if the compression coil spring 17 is inserted into the spring chamber 16 that is short in the direction of the central axis O-O, the compressed length of the compression coil spring 17 will be significantly larger than the value before compression, and the elastic reaction force will increase accordingly, resulting in a large pressure acting on the operator's hand.

In the accidents where the worker's hand is pinched as described above, the fingertip is usually pinched. It is reasonable to recognize that the distance between the small diameter guide rod 7 and the electrode guide pin 10 when the finger is pinched, that is, the pinch danger distance L2 corresponding to the thickness of the finger, is about 16 to 19 mm for male workers and about 13 to 16 mm for female workers. Under such dimensions, the distance L1 in the direction of the central axis O-O of the spring chamber 16 is set to be three times or more the pinch danger distance L2 when the worker's hand is pinched between the small diameter guide rod 7 and the electrode guide pin 10. Therefore, the shape of the spring chamber space is elongated, and even when the finger is pinched as described above, the deflection length of the compression coil spring 17 can be made smaller than the length before the deflection, and the finger can be pinched at the initial stage of deformation of the compression coil spring 17, so that the elastic pressure force on the finger can be reduced.

Since the detected part 35 advances and retreats within the long hole 37 of the outer cylinder 18 without protruding from the long hole 37, it does not interfere with the lid member 41, which is convenient for normal detection operation. Also, by presetting the position for fixing the lid member 41 to the outer cylinder 18 and the position for attaching the sensor 40 to the lid member 41, the relative positions of the detected part 35 stopped in the normal position and the sensor 40 can be accurately set, ensuring good operability.

Since the dimensional relationship between L1 and L2 is as described above and the spring chamber 16 can be made sufficiently elongated, it becomes easier to select the wire diameter, coil center diameter, effective number of turns, etc. of the compression coil spring 17, and it becomes easier to determine a spring constant that minimizes the spring reaction force acting on the operator's hand.

As described above, the device of the present invention reduces the clamping force acting on the worker's hand when the worker's hand is pinched between the tip of the supply rod of the projection nut and the guide pin of the electric resistance welding electrode, and can therefore be used in a wide range of industrial fields, such as automobile body welding processes and sheet metal welding processes for home appliances.

Reference Signs List 1 Projection nut 5 Supply rod 6 Large diameter rod 7 Small diameter guide rod 8 Slide hole 9 Fixed electrode 10 Electrode guide pin 11 Steel plate part 13 End surface 14 Inner end surface 15 Movable electrode 16 Spring chamber 17 Compression coil spring 18 Outer cylinder 19 Square hole 21 Temporary stop chamber 30 Air cylinder 32 Slot 33 Protrusion 34 Fixed portion 35 Detected portion 36 Lower end surface (extrusion surface)
37 Long hole 38 Lower end surface 40 Sensor 41 Cover member O-O Central axis L1 Distance in the central axis direction of the spring chamber L2 Pinch danger distance

Claims (1)

In a projection nut that is stopped at a predetermined position, a small-diameter guide rod of a supply rod is pierced in a skewer-like manner through a screw hole of the projection nut, and the projection nut is supplied to an electrode for electric resistance welding,
The supply rod is accommodated in an outer cylinder in a state in which it can advance and retreat, and is composed of a tubular large-diameter rod having a slide hole formed therein, and the small-diameter guide rod inserted into the slide hole in a state in which it can advance and retreat,
The finger of the operator that is pinched between the small diameter guide rod and the electrode guide pin is to be protected.
a sensor is provided to detect a relative displacement of the small diameter guide rod in a retreating direction relative to the large diameter rod when an operator's finger is pinched between the small diameter guide rod and the electrode guide pin during the advancement of the supply rod,
The large diameter rod is provided with a long hole having a lower end surface in a direction of a central axis of the supply rod,
a projection fixed to the small diameter guide rod and detected by the sensor is disposed in a state of protruding outward from the long hole;
a long hole having a shape and dimensions substantially the same as those of the long hole provided in the large diameter rod is formed in the outer cylinder;
The protrusion to be detected is configured to move forward and backward within the long hole provided in the outer cylinder,
The welding electrode is stopped from advancing in response to a signal from the sensor.
A spring chamber is formed between an end of the small diameter guide rod in the slide hole and an inner end surface of the slide hole,
A compression coil spring is disposed in the spring chamber to impart tension to the small diameter guide rod in the pushing direction,
The distance in the central axis direction of the spring chamber is set to be 3 times or more and less than 5 times the pinch danger distance, which is set when the operator's finger is pinched between the small diameter guide rod and the electrode guide pin, thereby reducing the spring reaction force on the operator's finger and avoiding insufficient pushing force of the compression coil spring for the small diameter guide rod,
A projection nut supply rod device characterized in that the maximum protrusion length of the small diameter guide rod relative to the large diameter rod is set by configuring the detection protrusion to be pressed against the lower end surface of the long hole provided in the large diameter rod by the tension of the compression coil spring.

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