JP7240138B2 - Collet assembly for stud welding gun - Google Patents

Description

The present invention relates to an improved collet that is attached to the tip of a stud welding gun and used to hold the stud.

Conventionally, a collet is provided at the tip of a stud welding gun to hold the stud and allow the welding current to flow.

FIG. 9 is a partial cross-sectional view of a welding gun for conventional capacitor discharge stud welding.

In the drawing, reference numeral 100 indicates a cylindrical housing, and a cap 101 is detachably attached to the rear end of this housing 100 . A handle 102 is provided on the housing 100 and a trigger button 103 is provided on the handle 102 .

Inside the housing 100, a tubular body 104 made of a conductive material is slidably supported in the axial direction by bearings (not shown). A collet 105 for attaching the stud S is inserted into the tip of the tubular body 104 , and the collet 105 is fixed to the tubular body 104 with a tightening nut 106 .

FIG. 10 is a schematic plan view of a conventional collet 105. FIG.

As shown in the drawing, the collet 105 comprises a cylindrical body 110 formed with a plurality of slits 111 longitudinally extending at equal angles around its central axis and a plurality of divided gripping pieces 113, and is used. By pushing the stud S from the tip of the collet 105 while opening the gripping piece 113, the stud S is held by the collet 105, that is, the gripping piece 113, with an appropriate gripping force.

Patent No. 5812685

As described above, the collet 105 is configured to hold the stud S by providing the slits 111 and imparting radial elasticity to the gripping pieces 113 . By the way, in the process of slitting the collet 105 during its manufacture, the gripping piece 113 expands in diameter toward the tip of the collet (stud insertion side). Therefore, in the final assembly process, the root portion of the grasping piece 113 of the collet 105 is tightened radially inward with a tool such as pliers, and the grasping piece 113 is narrowed toward the tip so as to reduce the diameter of the stud. In addition, an O-ring 114 is attached to an appropriate location to maintain the gripping force.

In addition, at a welding site, the gripping piece 113 is deformed into a shape that spreads outward in the radial direction due to repeated use such as thermal effects during welding, oblique insertion or prying during detachment of the stud, and the gripping force weakens. In order to solve this problem, the user periodically tightens the root portion of the grasping piece 113 of the collet 105 radially inward with a tool such as pliers, so that the grasping piece 113 moves toward the tip. It was necessary to restore the gripping force by narrowing the diameter so as to reduce the diameter.
Studs include male-threaded studs and female-threaded studs, and it is common to use the same collet in correspondence with the collet for management and convenience in welding work. For example, an M6 male stud uses the same collet as an M3 female stud with an outer diameter of 6 mm, and an M8 male stud uses an 8 mm outer diameter and the same as an M4 or M5 female stud. A collet of M10 external thread is used, and the same collet as a female threaded stud with an external diameter of 10 mm and an internal thread of M5 or M6 is used. However, most male threaded studs are manufactured by rolling, and even if they are within the thread standard, there is a large variation in the outer diameter. Female threaded studs are often manufactured by cutting, and their outer diameter is about φ6 mm and almost uniform.
This allows fine adjustment of the holding force for attaching the stud to the collet even when the same collet is actually used.

However, in the above-described conventional method, the extent to which the grasping piece 113 of the collet 105 is squeezed depends on the operator's sense. There is a problem that the stud S may loosen due to In addition, in the conventional method of adjusting the grasping force of the collet 105, which is important for grasping the stud S, only by the operator's feeling, the operator is required to have a high degree of skill, which imposes a burden on the operator. Become. And above all, it is troublesome to periodically squeeze the collet with pliers or the like.

In addition, the rubber O-ring 114 at the tip of the gripping piece is susceptible to deterioration under the influence of welding spatter, welding heat, welding atmosphere, etc., and must be frequently replaced at the welding work site. be.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described conventional problems and to provide a collet assembly that allows anyone to easily adjust the gripping force of the collet.

A collet assembly according to the present invention comprises a cylindrical body, a plurality of slits extending longitudinally at equal angles around the central axis of the cylindrical body to form a plurality of divided gripping pieces, and a collet body. and a collet cover covering at least the outer periphery of the gripping pieces of the collet body, wherein a male fitting portion is formed at least rearward of the slit portion on the outer peripheral surface of the collet body, and the collet cover A constricted portion having an inner diameter substantially equal to or smaller than at least the outer diameter of the gripping piece portion of the collet main body is provided on the inner peripheral surface thereof, and when the collet cover is attached to the collet main body, the constricted portion is aligned with the collet main body. A female fitting portion configured to press the gripping piece radially inward by contacting the gripping piece at its tip or root portion and engaging with the male fitting portion of the collet body is formed on the inner peripheral surface of the gripping piece. It is characterized by being formed in the axial rear part of the.

The constricted portion of the collet cover may have an inner diameter that does not vary in the axial direction, the inner diameter being approximately the same as or smaller than the outer diameter of the gripping piece portion of the collet body, and the collet cover being attached to the collet body. , the base portion of the gripping piece may contact the constricted portion of the collet cover to constrict the gripping piece.

Further, the narrowed portion of the collet cover may have an inner diameter that decreases in the axial direction toward the tip, and at least the narrowest diameter is approximately the same as or smaller than the outer diameter of the gripping piece portion of the collet body. Alternatively, when the collet cover is attached to the collet body, the tip of the gripping piece comes into contact with the constricted portion of the collet cover to constrict the gripping piece.

Furthermore, a slit window may be provided at the end of the slit portion of the collet body.

Also, the male fitting portion of the collet body and the female fitting portion of the collet cover may be formed by screw fitting.

Furthermore, a flange portion may be provided at the tip of the collet cover.

The collet cover only needs to be insulated between the collet body and the collet cover, and can be made of a metal material with an insulating coating, or preferably molded of a resin material.

A collet assembly according to the present invention comprises a cylindrical body, a plurality of slits extending longitudinally at equal angles around the central axis of the cylindrical body to form a plurality of divided gripping pieces, and a collet body. and a collet cover covering at least the outer periphery of the gripping pieces of the collet body, wherein a male fitting portion is formed at least rearward of the slit portion on the outer peripheral surface of the collet body, and the collet cover A constricted portion having an inner diameter substantially equal to or smaller than at least the outer diameter of the gripping piece portion of the collet main body is provided on the inner peripheral surface thereof, and when the collet cover is attached to the collet main body, the constricted portion is aligned with the collet main body. A female fitting portion configured to press the gripping piece radially inward by contacting the gripping piece at its tip or base portion and engaging with the male fitting portion of the collet body is formed on the inner peripheral surface of the gripping piece. is formed at the rear portion in the axial direction of the collet body, the operator simply attaches the cylindrical cover to the collet body, and the constricted portion contacts the gripping piece of the collet body at its tip or root portion to extend the diameter. By pressing inward, the gripping piece can be reduced to a diameter that can exert a gripping force for gripping the stud, and the gripping force of the stud can be maintained at a certain value or more. As a result, it is not necessary for the operator to periodically squeeze the root portion of the gripping piece of the collet body with a tool such as pliers. It becomes possible to keep

The narrowed portion of the collet cover is formed so that the inner diameter thereof does not change in the axial direction, and the inner diameter is substantially the same as or smaller than the outer diameter of the gripping piece portion of the collet body, and the collet cover is formed into the collet body. When the collet cover is attached, the base portion of the gripping piece comes into contact with the constricted portion of the collet cover, and the gripping piece is squeezed. It is narrowed obliquely from the tip toward the tip. As a result, when the collet cover is attached, a gap is created between the outer surface of the gripping piece and the inner surface of the drawn portion, which widens toward the tip, and when the stud is inserted, the gripping piece spreads outward in the radial direction. and the elastic force of the gripping pieces is maintained. In addition, by preparing multiple collet covers with different inner diameters of the constricted part, it is possible to use male and female threaded studs with almost the same outer diameter simply by replacing the collet cover without replacing the collet body. become.

Further, the narrowed portion of the collet cover is formed such that its inner diameter is axially reduced toward the tip, and at least the narrowest diameter is substantially equal to or smaller than the outer diameter of the gripping piece portion of the collet body. Also, when the collet cover is attached to the collet body, the tip of the gripping piece comes into contact with the squeezed portion of the collet cover, and the gripping piece is squeezed. It is possible to change the contraction amount of the gripping piece only by changing . Accordingly, this allows the use of male and female studs having substantially the same outer diameter in the same collet cover without providing multiple collet covers.

The collet cover restrains the deformation of the gripping piece at the tip of the contracted portion of the collet cover, thereby improving the durability.

FIG. 4 is a schematic perspective view of the collet assembly according to the present invention with the collet cover body removed from the collet body; FIG. 4 is a diagram showing a state where a collet cover body is attached to a collet body; 3A is a schematic top view of an embodiment of a collet body according to the present invention, and FIG. 3B is an axial cross-sectional view of the collet body shown in FIG. 3A; FIG. (a) is an axial cross-sectional view of a first embodiment of a collet cover according to the present invention, and (b) is a view showing a state where the collet cover is attached to a collet body. 5 is a schematic diagram showing the principle of tightening the collet body by the collet cover shown in FIG. 4; FIG. FIG. 4 is an axial cross-sectional view of a second embodiment of the collet cover according to the invention; 7A and 7B are diagrams showing a state in which the collet cover shown in FIG. 6 is attached to the collet body; FIG. (a) and (b) are schematic diagrams showing the principle by which the collet cover shown in FIG. 6 tightens the collet body. 1 is a partial cross-sectional view of a welding gun for capacitor discharge stud welding; FIG. 1 is a schematic plan view of a conventional collet; FIG.

Embodiments of the collet assembly according to the present invention will be described below with reference to several embodiments shown in the accompanying drawings.

1 is an exploded perspective view of a collet assembly according to the present invention, FIG. 2 is a view showing a collet cover body attached to a collet body, and FIG. 3(a) is an embodiment of a collet body according to the present invention. 3(b) is an axial sectional view of the collet body shown in FIG. 3(a). In the figure, reference numeral 1 indicates a collet body, and reference numeral 10 indicates a collet cover.

The collet body 1 has a cylindrical body 2 open at both ends. The front portion of the cylindrical body 2 is formed with a plurality of slits 3 extending longitudinally at the same angle around the central axis A, and a slit window 4 located at the rear end of the slit 3. there is By forming the slit 3 and the slit window 4 , the cylindrical main body 2 is formed with a plurality of divided gripping pieces 5 . The gripping piece 5 thus formed has a gutter-like shape in which the rear end is cantilevered on the cylindrical main body 2 and has some elasticity radially outward and inward. In this embodiment, four slits 3 are formed at an equal angle of 90°, so that four gripping pieces 5 are formed.

Although the slotted window 4 may be omitted, providing it facilitates the slotting process and enables adjustment of the spring property.

As shown in FIG. 3(b), the inner and outer peripheries of the tip of the gripping piece 5 are chamfered respectively, and the inner diameter of the gripping piece 5 is sized according to the stud to be used. .

As shown in FIGS. 3(a) and 3(b), behind the slotted window 4 on the outer peripheral surface of the cylindrical body 2, a threaded portion as a female fitting portion of the collet cover 10, which will be described later, is screwed. A threaded portion 6 is formed as a male fitting portion, and an annular cover stopper 7 projecting radially outward is formed behind the threaded portion 6 .

Next, an embodiment of the collet cover 10 attached to the collet main body 1 constructed as described above will be described.

FIG. 4(a) is a longitudinal cross-sectional view of an embodiment of the collet cover according to the present invention, and FIG. In FIG. 4(b) the collet cover 10 is shown in longitudinal section. 5 is a schematic diagram showing the principle of tightening the collet body by the collet cover shown in FIG.

The collet cover 10 has a cylindrical body 11 open at both ends. The cylindrical body 11 has a squeeze portion 12 for squeezing the gripping pieces 5 of the collet body 1 and an introduction portion 13 for introducing the collet body 1 .

The introduction part 13 has an inner diameter that allows insertion of the grip piece 5 of the collet body 1 , that is, an inner diameter that is larger than the outer diameter of the grip piece 5 . A threaded portion 14 is formed.

The constricted portion 12 has an inner diameter T2 that is substantially the same as or smaller than the outer diameter T1 of the gripping piece 5 of the collet body 1 . The inner diameter T2 of the narrowed portion 12 is set to a value suitable for narrowing the gripping piece 5 to a diameter for gripping the stud S according to the length and outer diameter of the gripping piece 5 of the collet body 1 . Specifically, in this embodiment, the outer diameter T1 of the gripping piece 5 of the collet body 1 is 8.5 mm, whereas the inner diameter T2 of the narrowed portion 12 of the collet cover when used for an externally threaded stud is 8.5 mm. 0.34 mm, and the inner diameter T2 of the constricted portion 12 of the collet cover when used for an internally threaded stud is 8.55 mm. The narrowed portion 12 has a shape in which the inner diameter T2 does not change over the entire length.

A flange portion 15 protruding radially inward is formed at the tip of the narrowed portion 12 of the collet cover 10 . The inner diameter of the flange portion 15 is set to a value that allows the stud S to be gripped to pass therethrough but does not allow the collet body 1 to pass therethrough.

When the collet cover 10 configured as described above is inserted into the collet body 1 from the introduction portion 13 and screwed into the collet body 1 until the rear end surface 11a comes into contact with the cover stopper 7 provided on the collet 1, The gripping piece 5 of the collet body 1 is inserted into the drawn portion 12 up to its root portion, and the tip of the collet body 1, that is, the tip of the gripping piece 5 is positioned in front of the flange portion 15. there is

Although the flange portion 15 may be omitted, providing it can prevent spatter during welding from entering the gap between the collet body 1 and the collet cover 10 .

When the collet cover 10 is attached to the collet main body 1 , the rear edge 12 a of the drawn portion 12 comes into contact with the outer periphery of the root portion of the grasping piece 5 and presses the grasping piece 5 . As a result, the gripping pieces 5 of the collet body 1 are narrowed so that the diameter of the gripping pieces 5 decreases toward the tip. As a result, a gap 16 is formed between the inner peripheral surface of the drawn portion 12 and the outer peripheral surface of the gripping piece 5 in the collet cover 10 . This gap 16 widens toward the tip.

By the action described above, the gripping pieces 5 of the collet body 1 are narrowed radially inward by the collet cover 10, and a gap is formed between the outer peripheral surface of the gripping pieces 5 and the inner peripheral surface of the narrowed portion 12. Therefore, the elasticity of the gripping piece 5 is ensured.

For example, as described above, a stud having an external thread and a stud having an internal thread have slightly different outer diameters. Specifically, since the outer thread is formed by rolling, the outer diameter of the stud with the outer thread is slightly smaller than the outer diameter of the stud with the inner thread. By preparing a plurality of collet covers 10 having different inner diameters of the drawn parts 12, the collet cover 10 can be changed without removing the collet body 1 from the stud welding gun each time the outer diameter of the stud changes. It becomes possible to easily obtain a gripping force adapted to the stud to be used.

Next, a second embodiment of the collet cover according to the present invention will be described with reference to FIGS. 6 to 8. FIG.

The collet cover 20 according to the second embodiment has a cylindrical main body 21, and the cylindrical main body 21 is formed with a constricted portion 22 and an introduction portion 23. As shown in FIG.

The introduction part 23 has an inner diameter that allows insertion of the grip piece 5 of the collet body 1 , that is, an inner diameter that is larger than the outer diameter of the grip piece 5 . A threaded portion 24 is formed.

The narrowed portion 22 includes a guide portion 22a having an inner diameter T3 larger than the outer diameter T1 of the gripping piece 5 of the collet body 1, and a guide portion 22a provided at the front portion of the narrowed portion 22, which tapers radially inward toward the front. and a constricted portion 22b having a diameter. The inner diameter T4 of the tip of the guide portion 22a is smaller than the outer diameter T1 of the gripping piece 5 of the collet body 1 . Therefore, the tapered portion 22b is smoothly reduced in diameter from an inner diameter T3 larger than the outer diameter T1 of the gripping piece 5 to an inner diameter T4 smaller than the outer diameter T1 of the gripping piece 5. FIG. Specifically, in this embodiment, the outer diameter T1 of the gripping piece 5 of the collet body 1 is 8.5 mm, whereas the inner diameter T3 of the guide portion 22a of the narrowed portion 2 is 8.6 mm. The inner diameter T4 of the leading edge of the portion 22b is 8.25, and the angle with respect to the central axis of the throttle portion 22b is 14°.

Reference numeral 25 in the drawing denotes a flange provided at the tip of the collet cover 20. As shown in FIG.

According to the collet cover 20 configured as described above, when the collet body 1 is inserted through the insertion portion 23, the gripping pieces 5 of the collet body 1 are inserted without being pressed by the guide portion 22a of the drawn portion 22. be. When the tip of the gripping piece 5 is inserted into the constricted portion 22b, the constricting portion 22b having a tapered diameter presses the tip of the gripping piece 5 radially inward, and the gripping piece 5 is constricted.

Since the narrowed portion 22 b is formed in a tapered shape, the amount of narrowing of the gripping piece 5 in the collet body 1 changes depending on the amount of insertion of the collet body 1 into the collet cover 20 .

That is, when the collet body 1 is inserted to the position shown in FIGS. 7(a) and 8(a), the portion of the narrowed portion 22b with the smallest inner diameter comes into contact with the tip of the gripping piece 5 and pushes the gripping piece 5 inward. 7(b) and 8(b). 2, the amount of constriction of the gripping piece 5 becomes smaller than when the collet body 1 is inserted to the position shown in FIG.

As a result, by changing the amount of insertion of the collet body 1 into the collet cover 20, the externally threaded stud and the internally threaded stud having substantially the same diameter can be gripped without changing the collet body 1.
The engagement between the collet main body 1 and the collet cover 10 or 20 may be achieved by taper fitting, in which the collet main body 1 is provided with a male taper and the collet cover is provided with a female taper, in addition to screw engagement.

Incidentally, the collet cover 20 is preferably molded with resin. When the stud S is inserted into the collet body 1, the gripping piece 5 spreads outward in the radial direction, but the movement of this gripping piece 5 is restricted by the inner wall of the collet cover 20, so the elastic force of the gripping piece 5 is maintained. will be

REFERENCE SIGNS LIST 1 collet main body 2 cylindrical main body 3 slit 4 slit window 5 grip piece 6 screw portion 7 cover stopper

REFERENCE SIGNS LIST 10 collet cover 11 cylindrical main body 12 throttle portion 13 introduction portion 14 screw portion 15 flange portion 16 gap

20 Collet cover 21 Cylindrical body 22 Squeezed part 22a Guide part 22b Squeezed part 23 Introduction part 24 Screw part 25 Flange part

A Center axis of collet body T1 Outer diameter of gripping piece of collet body T2 Inner diameter of constricted part of collet cover T3 Inner diameter of guiding part of constricted part of collet cover T4 Inner diameter of tip of constricted part of collet cover

100 cylindrical housing 101 cap 102 handle 103 trigger button 104 tubular body 105 collet 106 tightening nut

110 cylindrical main body 111 slit 113 grip piece 114 O-ring

Claims (6)

A collet formed by providing a plurality of slits extending longitudinally at equal angles along the longitudinal direction of the cylindrical body around the central axis of the cylindrical body to form a plurality of divided gripping pieces. the main body;
a collet cover that covers at least the outer periphery of the gripping piece of the collet body,
A male fitting portion is formed at least rearward of the slit portion on the outer peripheral surface of the collet body,
The collet cover is provided with a constricted portion having an inner diameter substantially equal to or smaller than at least the outer diameter of the gripping piece portion of the collet body, and the collet cover is attached to the collet body. Sometimes, the constricted portion is configured to contact and press the gripping piece of the collet body radially inwardly at its root portion , and a female engaging the male mating portion of the collet body. A collet assembly, characterized in that a die fitting portion is formed at an axially rearward portion of an inner peripheral surface of the collet assembly. A collet formed by providing a plurality of slits extending longitudinally at equal angles along the longitudinal direction of the cylindrical body around the central axis of the cylindrical body to form a plurality of divided gripping pieces. the main body;
a collet cover that covers at least the outer periphery of the gripping piece of the collet body;
with
A male fitting portion is formed at least rearward of the slit portion on the outer peripheral surface of the collet body,
The collet cover has a narrowed portion extending in the direction of the central axis of the inner peripheral surface thereof, the narrowed portion having an inner diameter larger than the outer diameter of the gripping piece, and a front portion provided in front of the guide portion. a constricted portion that tapers radially inward toward the
When the collet cover is attached to the collet body, the constricted portion contacts the gripping piece of the collet body at its tip portion and presses it radially inward, and the male type of the collet body. A female mating portion that engages with the mating portion is formed at the axial rear portion of the inner peripheral surface.
A collet assembly characterized by: 3. A collet assembly as claimed in claim 1 or 2, characterized in that a slit window is provided at the end of the slit portion of the collet body. 4. The collet assembly according to claim 1, wherein the male fitting portion of the collet body and the female fitting portion of the collet cover are screw fitting. 5. The collet assembly according to any one of claims 1 to 4, wherein a flange portion is provided at the tip of the collet cover. The collet assembly according to any one of claims 1 to 5 , wherein the collet cover is molded from a resin material.

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