Device and method for forming end of coiled spring

Abstract

A coil spring end forming apparatus is provided that includes a pair of horizontally disposed parallel rollers; a mandrel; a stopper that is provided adjacent to the circumferential surface of the mandrel and is moved up or down and rotated integrally with the mandrel; a clamp jig that is provided so as to be movable toward or away from the mandrel and that holds a semi-formed spring in cooperation with the mandrel, and a pusher for pushing the semi-formed spring toward the stopper, wherein in a state in which the axis of the mandrel is positioned between the axes of the parallel rollers and the semi-formed spring, a clamp portion holds the semi-formed spring at the inner side of a triangle formed by the axes of the parallel rollers and the semi-formed spring and rotates around the axis along the winding direction of the semi-formed spring to form a pigtail portion at one end of the semi-formed spring, and a coil spring end forming method is further provided.

Claims

1. A coil spring end forming apparatus comprising: a pair of horizontally disposed parallel rollers that rotate in the same direction and on which is mounted a cylindrical coil-shaped semi-formed spring that tends toward formation of a pigtail portion at a first end thereof; a mandrel, which is a cylindrical body having an outer diameter smaller than an inner diameter of the semi-formed spring, that is horizontally disposed near one end of the parallel rollers; a stopper that is provided coaxially and integrally with the mandrel and receives the first end of the semi-formed spring, wherein a relative position of the stopper and the mandrel does not change; a clamp jig that is provided adjacent to the stopper so as to be movable toward or away from the mandrel, that forms a clamp portion with the mandrel and the stopper, and that holds the first end of the semi-formed spring in cooperation with the mandrel; and a pusher that pushes a second end of the semi-formed spring toward the stopper on the parallel rollers, wherein the clamp portion is configured such that in a state in which the axis of the mandrel is positioned between axes of the parallel rollers and an axis of the semi-formed spring, the clamp portion holds the first end of the semi-formed spring at an inner side of a triangle formed by the axes of the parallel rollers and the semi-formed spring, and rotates around the axis of the mandrel in a winding direction of the semi-formed spring to form the pigtail portion at the first end of the semi-formed spring, and the coil spring end forming apparatus is configured such that no compression force perpendicular to an axis of a filament of the semi-formed coil spring is applied on the semi-formed coil spring between the pusher and the mandrel while forming the pigtail portion.

2. The coil spring end forming apparatus according to claim 1, wherein the clamp portion rotates around the axis of the mandrel and, at the same time, the clamp portion or the parallel rollers are relatively moved up or down to form the pigtail portion at the first end of the semi-formed spring.

3. The coil spring end forming apparatus according to claim 1, wherein when the semi-formed spring is clamped by the clamp portion, the pusher is moved away from the semi-formed spring.

4. The coil spring end forming apparatus according to claim 2, wherein when the semi-formed spring is clamped by the clamp portion, the pusher is moved away from the semi-formed spring.

5. The coil spring end forming apparatus according to claim 1, wherein the clamp portion rotates around the axis of the mandrel, the parallel rollers are moved down such that the clamp portion is moved up relative to the parallel rollers, and the pigtail portion is formed at the first end of the semi-formed spring.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a side view showing the constitution of a coil spring end forming apparatus according to Embodiment 1;

(2) FIG. 2 is an end face view showing the constitution of the coil spring end forming apparatus according to Embodiment 1;

(3) FIG. 3 is an explanatory view of the coil spring end forming apparatus shown in FIGS. 1 and 2 showing the operation of parts until a semi-formed spring placed on parallel rollers is pushed onto a stopper by a pusher;

(4) FIG. 4 is an explanatory view of the coil spring end forming apparatus shown in FIGS. 1 and 2 showing the operation of parts until the semi-formed spring placed on the parallel rollers is pushed onto the stopper by the pusher;

(5) FIG. 5 is an explanatory view of the coil spring end forming apparatus shown in FIGS. 1 and 2 showing the operation of parts when one end of the semi-formed spring is held by a clamp portion;

(6) FIG. 6 is an explanatory view of the coil spring end forming apparatus shown in FIGS. 1 and 2 showing the operation of parts when one end of the semi-formed spring is held by the clamp portion;

(7) FIG. 7 is an explanatory view of the coil spring end forming apparatus shown in FIGS. 1 and 2 showing the operation of parts immediately after formation of a pigtail portion is started;

(8) FIG. 8 is an explanatory view of the coil spring end forming apparatus shown in FIGS. 1 and 2 showing the operation of parts immediately after formation of the pigtail portion is started;

(9) FIG. 9 is an explanatory view of the coil spring end forming apparatus shown in FIGS. 1 and 2 showing the operation of parts during formation of the pigtail portion;

(10) FIG. 10 is an explanatory view of the coil spring end forming apparatus shown in FIGS. 1 and 2 showing the operation of parts during formation of the pigtail portion;

(11) FIG. 11 is an explanatory view of the coil spring end forming apparatus shown in FIGS. 1 and 2 showing the operation of parts during formation of the pigtail portion;

(12) FIG. 12 is an explanatory view of the coil spring end forming apparatus shown in FIGS. 1 and 2 showing the operation of parts during formation of the pigtail portion;

(13) FIG. 13 is an explanatory view of the coil spring end forming apparatus shown in FIGS. 1 and 2 showing the operation of parts at completion of formation of the pigtail portion; and

(14) FIG. 14 is an explanatory view of the coil spring end forming apparatus shown in FIGS. 1 and 2 showing the operation of parts at completion of formation of the pigtail portion.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiment 1

(15) As shown in FIGS. 1 and 2, a coil spring end forming apparatus 100 according to Embodiment 1 has a clamp portion 2, a rotation driving portion 4 for rotating the clamp portion 2 around an axis A-A, a base 6 for supporting the rotation driving portion 4, a pair of parallel rollers 8 provided adjacent to the rotation driving portion 4 and supported horizontally and in parallel with each other, a platform 10 for supporting the parallel rollers 8 from below, a pusher 12 provided across the parallel rollers 8 and relative to the clamp portion 2, and an actuator 14 fixed above the platform 10 and moving the pusher 12 toward or away from the clamp portion 2.

(16) As indicated by arrows d, the platform 10 is supported by the base 6 so as to be moved up or down. The base 6 has a ball screw mechanism 16 for moving the platform 10 up or down, and a vertical guide mechanism 18 for supporting the platform 10 for up or down movement and vertically guiding it. The ball screw mechanism 16 and the vertical guide mechanism 18 are relatively provided to interpose the platform 10 therebetween. FIG. 1 shows the constitution of the platform 10 and the ball screw mechanism 16 and the vertical guide mechanism 18 is omitted.

(17) The platform 10 has a motor 8A for rotatably driving the parallel rollers 8 and a timing belt 8B for transmitting the rotational force of the motor 8A to the two parallel rollers 8.

(18) The clamp portion 2 has a cylindrical stopper 20 on which a cylindrical semi-formed spring 30 placed on the parallel rollers 8 abuts, a mandrel 22 protruded in the center portion of the end face of the stopper 20 coaxially with the stopper 20, and a clamp jig 24 provided on the end face of the stopper 20 so as to be moved toward or away from the mandrel 22 and holding the end of the semi-formed spring 30 in cooperation with the mandrel 22. The clamp portion 2 is formed in such a manner that when the stopper 20 and the mandrel 22 are rotated around the axis A-A, the clamp jig 24 is rotated integrally.

(19) The rotation driving portion 4 has a body 4A provided on the base 6 so as to be moved toward or away from the parallel rollers 8 in the direction of arrows a and rotatably supporting the clamp portion 2 around the axis A-A, a driving motor 4B for rotating the clamp portion 2 around the axis A-A, and a power transmission supporting portion 4C for fixing the driving motor 4B above the body 4A and incorporating a transmission mechanism (not shown) for transmitting the rotational force of the driving motor 4B to the clamp portion 2. The base 6 has a moving mechanism (not shown) for moving the body 4A in the direction shown by a pair of arrows.

(20) The ball screw mechanism 16 has a ball screw 16A rotated by a motor 16D fixed to the base 6, a nut portion 16B fixed to the side surface of the platform 10 and threaded to the ball screw 16A, a ball screw supporting portion 16C fixed to the base 6 and vertically supporting the lower end of the ball screw 16A, and a timing belt 16E for transmitting the rotational force of the motor 16D to the ball screw 16A. When the motor 16D is rotated, the timing belt 16E transmits the rotational force of the motor 16D to the ball screw 16A to rotate the ball screw 16A. The nut portion 16B is moved up or down so that the platform 10 to which the nut portion 16B is fixed is also moved up or down.

(21) The vertical guide mechanism 18 has a rail 18B provided vertically, a moving head 18A fixed to the side surface on the opposite side of the side provided with the nut portion 16B on the platform 10 and running on the rail 18B, and a rail support 18C erected vertically on the base 6 and supporting the rail 18B. When the platform 10 is moved up or down by the ball screw mechanism 16, the elevating head 18A fixed to the platform 10 runs on the rail 18B to vertically guide the platform 10. The platform 10 is moved up or down in the state that its top surface is held horizontally.

(22) The operation of the coil spring end forming apparatus 100 will be described using FIG. 3 and thereafter. In FIG. 3 and thereafter, the rotation driving portion 4, the base 6, and the platform 10 are omitted.

(23) As shown in FIGS. 3 and 4, the parallel rollers 8 are rotated in the counterclockwise direction in the state that the semi-formed spring 30 is placed on the parallel rollers 8 to rotate the semi-formed spring 30 in the clockwise direction, as indicated by an arrow b, and the pusher 12 pushes the semi-formed spring 30 toward the stopper 20. The axis of the mandrel 22, that is, the axis A-A of the stopper 20 is positioned below an axis B-B of the semi-formed spring 30.

(24) When one end of the semi-formed spring 30 is inserted between the mandrel 22 and the clamp jig 24, as shown in FIGS. 5 and 6, rotation of the parallel rollers 8 is stopped to hold one end of the semi-formed spring 30 by the mandrel 22 and the clamp jig 24. As shown in FIG. 5, the position holding the semi-formed spring 30 by the stopper 20 and the clamp jig 24 is on the inner side of a triangle T formed by the axis B-B of the semi-formed spring 30 and the axes of the two parallel rollers 8. After one end of the semi-formed spring 30 is held by the mandrel 22 and the clamp jig 24, the pusher 12 may be moved away from the other end of the semi-formed spring 30, or as shown in FIG. 5 and thereafter, it may remain contact with the other end of the semi-formed spring 30.

(25) After one end of the semi-formed spring 30 is held by the mandrel 22 and the clamp jig 24, as shown in FIGS. 7 and 8, rotation around the axis A-A of the stopper 20 of the clamp portion 2 is started. As indicated by an arrow c, the rotational direction of the clamp portion 2 is the winding direction of the semi-formed spring 30, that is, the clockwise direction. When rotation of the clamp portion 2 is started, as shown in FIG. 7 and thereafter, the force in a direction of bending inward by the clamp jig 24 and the mandrel 22 is exerted on one end of the semi-formed spring 30. The semi-formed spring 30 is rotated in the direction of the arrow b around the portion sandwiched between the clamp jig 24 and the mandrel 22 to exert a reaction force F in the direction extending outward on one or both of the parallel rollers 8. The reaction force F is received by the parallel rollers 8 to prevent the semi-formed spring 30 from extending outward.

(26) When rotation of the clamp portion 2 is started, as shown in FIGS. 9 to 12, the clamp portion 2 is rotated around the axis A-A, and the ball screw mechanism 16 moves down the platform 10 and moves up the clamp portion 2 relative to the parallel rollers 8. The axis A-A of the stopper 20 is moved toward the axis B-B of the semi-formed spring 30. A pigtail portion can be formed in a predetermined position at one end of the semi-formed spring 30. By moving down the platform 10 and moving the rotation driving portion 4 relative to the base 6 so as to move the clamp portion 2 closer to the parallel rollers 8, a flat seat normal to the axis B-B of the semi-formed spring 30 can be formed at the end of the pigtail portion.

(27) As shown in FIGS. 13 and 14, when the clamp portion 2 is rotated through one revolution, holding of the semi-formed spring 30 by the mandrel 22 and the clamp jig 24 is released to take out the semi-formed spring 30 having the pigtail portion formed at one end. In FIGS. 13 and 14, in the semi-formed spring 30, the pigtail portion is substantially coaxial with the center portion. The axes of the pigtail portion and the center portion of the semi-formed spring 30 may be offset to each other. The position relation between the pigtail portion and the center portion can be set by an amount of moving-up of the clamp portion 2.

(28) As described above, in the coil spring end forming apparatus 100 according to Embodiment 1, the force extending the semi-formed spring 30 outward is received by one or both of the parallel rollers 8. No engaging structures for regulating movement of the semi-formed spring 30 in the radius direction are required. One end of the semi-formed spring 30 is securely held by the mandrel 22 and the clamp jig 24 during formation of the pigtail portion and cannot be moved longitudinally. No engaging structures for regulating movement of the semi-formed spring 30 in the axial direction are required.

EXPLANATION OF REFERENCE NUMERALS

(29) 2 Clamp portion

(30) 4 Rotation driving portion

(31) 6 Base

(32) 8 Parallel roller

(33) 10 Platform

(34) 12 Pusher

(35) 14 Actuator

(36) 16 Ball screw mechanism

(37) 20 Stopper

(38) 22 Mandrel

(39) 24 Clamp jig

(40) 30 Semi-formed spring

(41) 100 Coil spring end forming apparatus