Winding core for coil winding device

A winding core for a coil winding device having a column shape with corners each having a rounded cross-section is used for forming a coil by winding a wire around the winding core into the coil of a polygonal shape. The winding core includes a helical continuous surface extending spirally around an axis of the winding core.

BACKGROUND OF THE INVENTION

The present invention relates to a winding core for a coil winding device.

When a wire is bent into a generally square shape or any other polygonal shape in winding the wire around a winding core of a winder to form a coil, the wire is sprung back from the intended bending angle. In the coil winding device disclosed in Japanese Patent Application Publication No. 2010.4589, the winding core of the winder is formed helically with the springback taken into previous consideration. More specifically, the winding core includes four core bars each having a substantially rectangular cross-section with four rounded corners and the wire is wound around the winding core for N times (N is an integer of two or more) to form a coil. The winding core has winding tracks forming N steps for winding wire and the winding tracks are formed such that each four corners of the winding tracks are circumferentially deviated every step to make the winding core into a helical shape.

Referring toFIG. 9Ashowing the background art according to the above-cited Publication No. 2010-4589, the helical winding core100has winding tracks101,102,103,104and a step is formed between any two adjacent winding tracks, as shown inFIG. 9A. Each of the winding tracks101,102,103,104has a contacting surface with which the wire (flat wire)110is in perpendicular contact. The wire110is pressed against the winding core100by the guide member120of a pressing roller. The wire110pressed against the step by the guide member120is moved to the adjacent step formed between the winding tracks101,102,103,104, so that the wire110is damaged by the step. For preventing the above damage to the wire110, the winding tracks101,102,103,104may be widened or the width W of the winding tracks101,102,103,104may be increased, as shown inFIG. 9Bso that the wire110is not moved to the adjacent step. However, widening the tracks101,102,103,104widens the clearance between any two adjacent turns of the wire in the axial direction of the winding core100and increases the total length of the coil.

The present invention is directed to providing a winding core for a coil winding device by which damage to a wire hardly occurs and an increase of the total length of wound coil is prevented.

SUMMARY OF THE INVENTION

In accordance with the present invention, a winding core for a coil winding device having a column shape with corners each having a rounded cross-section is used for forming a coil by winding a wire around the winding core into the coil of a polygonal shape. The winding core includes a helical continuous surface extending spirally around an axis of the winding core.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following will describe a coil winding device according to a first preferred embodiment with reference toFIGS. 1 through 5. It is noted that the arrows X, Y and Z in the drawing show three different directions in the three-dimensional coordinate system of the coil winding device.

Referring toFIG. 1, reference numeral1designates a coil winding device. The coil winding device1includes a winder10having a winding core20. The coil winding device1is used for forming a coil by winding a flat wire50around the columnar winding core20into a coil of a generally rectangular shape. The flat wire50has a rectangular cross-section and is wound edgeways to form the coil. The winding core20is rotatably supported.

Referring also toFIGS. 2,3, the winding core20is divided into four core bars, namely a first core bar21, a second core bar22, a third core bar23and a fourth core bar24.

The winding core20as a whole has a generally square column shape with four corners, namely first through fourth corners C1, C2, C3, C4each of which is rounded. The first through fourth corners C1, C2, C3, C4have a rounded cross-section. The first core bar21has the first corner C1. The second core bar22has the second corner C2. The third core bar23has the third corner C3. The fourth core bar21has the fourth corner C4. L1inFIGS. 2 and 3indicates the axis of the square columnar winding core20.

The first through fourth core bars21,22,23,24have a shape of a twisted rod and the first through fourth corners C1, C2, C3, C4thereof have a helical continuous smooth surface extending spirally around the axis L1.

A first helical space G1is formed between the first and the second core bars21,22, as shown inFIGS. 1 and 3. Similarly, a second helical space G2is formed between the second and the fourth core bar22,24, a third helical space G3is formed between the first and the third core bar21,23and a fourth helical space G4is formed between the third and the fourth core bars23,24, as shown inFIGS. 1 and 3.

As shown inFIG. 3, the first through fourth core bars21,22,23,24are slidably supported by means of a slide mechanism such that the first through fourth core bars21,22,23,24can be moved toward and away from the center O of the winding core20. The arrows α inFIGS. 2 and 3show the directions in which the respective first through fourth core bars21,22,23,24are moved toward the center O. After the winding of the flat wire50is completed, the first through fourth core bars21,22,23,24slide inward or in the direction α, so that the contacting surfaces of the first through fourth core bars21,22,23,24with the flat wire50at the rounded first through fourth corners C1, C2, C3, C4are moved inward and separated away from the flat wire50.

The coil winding device1further includes a lower plate (bottom block)30and an upper plate (top block)31. As shown inFIG. 1, the first through fourth core bars21,22,23,24are disposed upright on the lower plate30. The upper plate31is provided on the top of the first through fourth core bars21,22,23,24. In other words, the first through fourth core bars21,22,23,24are supported and held between the lower plate30and the upper plate31in an upright position.

Referring toFIG. 4, an arm32is disposed above the upper plate31and extends horizontally. The arm32is fastened at the proximal end thereof to the upper plate31by bolts33,34. A center shaft35extends through the center part of the lower plate30. The center shaft35is supported at the lower part thereof by a bearing36so as to be movable up and down. The center shaft35extends also through the center of the upper plate31and is supported at the upper part thereof by a bearing37so as to be movable up and down.

The lower plate30has on the top surface thereof a plurality of guide members38. Similarly, the upper plate31has on the bottom surface thereof a plurality of guide members39. The first through fourth core bars21,22,23,24are slidable in radial direction toward and away from the center O of the winding core20while being guided by the guide members38,39.

The lower plate30has a stop projection40on the top surface thereof and the upper plate31has a stop projection41on the bottom surface thereof. The center shaft35extends through the center of the winding core20.

The center shaft35has three large-diameter portions35A,35C,35E and two small-diameter portions35B,35D. The large-diameter portion35A, the small-diameter portion35B, the large-diameter portion35C, the small-diameter portion35D and the large-diameter portion35E are positioned in this order from the bottom to the top of the center shaft35.

The first through fourth core bars21,22,23,24(winding core20) have on the inner peripheral surfaces thereof large-diameter portions25,27,29and small-diameter portions26,28. The large-diameter portion25, the small-diameter portion26, the large-diameter portion27, the small-diameter portion28and the large-diameter portion29are positioned in this order as seen from the bottom to the top of the winding core20. As shown inFIG. 5, the winding core20is pushed inward by an external actuator (not shown) such that the inner peripheral surfaces of the first through fourth core bars21,22,23,24are brought into contact with the outer peripheral surface of the center shaft35. Thus, the first through fourth core bars21,22,23,24are moved inward or toward the center O, so that the diameter of the winding core20is reduced.

The center shaft35is movable up and down. When the small-diameter portions26,28of the first through fourth core bars21,22,23,24and the small-diameter portions35B,35D of the center shaft35are in contact with each other, the first through fourth core bars21,22,23,24are located in the contracted position, as shown inFIG. 5. When the small-diameter portions26,28of the first through fourth core bars21,22,23,24and the large-diameter portions35A,35C of the center shaft35are in contact with each other, the first through fourth core bars21,22,23,24are located in the expanded position, as shown inFIG. 4. At this time, the first through fourth core bars21,22,23,24are placed in contact with the stop projections40,41formed on the lower and the upper plates30,31, respectively.

When the center shaft35is moved upward, the first through fourth core bars21,22,23,24of the winding core20are separated by being pushed away from each other in radial direction by steps of the center shaft35. Thus, the coil winding device1is placed in the expanded position shown inFIG. 4. When the center shaft35is moved downward, on the other hand, the large-diameter portions35A,35C,35E of the center shaft35are located in the large-diameter portions25,27,29of the first through fourth core bars21,22,23,24with clearances formed between the large-diameter portions35A,35C,35E and the large-diameter portions25,27,29, respectively. Then, the clearances are reduced by the external actuator. Thus, the coil winding device1is placed in the contracted position as shown inFIG. 5.

Winding of the wire is performed around the winding core20in the expanded position shown inFIG. 4and, after completion of the winding of wire, the wound wire (coil) is removed from the winding core20which is contracted as shown inFIG. 5. The flat wire50is wound while being guided along the winding core20by a guide member (not shown). In the winding, the flat wire50is pressed at the short side of the rectangular cross-section of the flat wire50against the winding surface (or contact surface) of the winding core20. In the winding of the flat wire50, the relative positions of the flat wire50and the winding core20in the vertical direction is changed. Specifically, the winding of the flat wire50is performed while the winding core20is being moved downward with the flat wire50kept at a predetermined height.

The following will describe the operation of the coil winding device1(winding core20) constructed as described above. With the center shaft35placed in the raised position as shown inFIG. 4, the small-diameter portions26,28of the first through fourth core bars21,22,23,24and the large-diameter portions35A,35C of the center shaft35are in contact with each other, so that the first through the fourth core bars21,22,23,24are located away from each other.

In this state of the winding core20, one end of the flat wire50is fixed to the winding core20of the winder10. The flat wire50is pressed against the peripheral surface of the winding core20and wound edgeways around the winding core20by rotating the winding core20, thereby forming a coil.

As shown inFIGS. 1 and 2, the first through fourth corners C1, C2, C3, C4corresponding to the outer peripheral surfaces (side surfaces) of the winding core20around which the flat wire50is wound are formed helically around the axis L1.

The winding core20has a helical shape which is formed with the springback of the wound flat wire50taken into consideration preciously, so that the flat wire50removed from the winding core20and sprung back takes an intended shape having no distortion.

After the winding of the flat wire50is completed, the center shaft35is moved downward and the small-diameter portions26,28of the first through fourth core bars21,22,23,24and the small-diameter portions35B,35D are in contact with each other, so that the first through the fourth core bars21,22,23,24are moved to the contracted position ofFIG. 5. That is, after winding of the flat wire50, the first through the fourth core bars21,22,23,24are moved inwardly or toward the axis L1, so that the wound flat wire50may be removed from the winding core20.

The winding angle of the winding core20is corrected by twisting the winding core20around the rotation center (center axis) of the winding core20by an amount of the springback of the winding core20. The first through fourth corners C1, C2, C3, C4have a helical continuous smooth surface extending spirally around the axis L1, so that the wire is hardly susceptible to a damage by the steps as described with reference toFIG. 9Aand an increase of the total length of the completed coil shown inFIG. 9Bis prevented. Since the first through fourth corners C1, C2, C3, C4of the winding core20have a helical continuous smooth surface such that the completed coil formed by bending slips thereon in the axial direction thereof, damage to the coil by the steps hardly occurs and an increase of the total length of the completed coil and twisting caused by springback are prevented.

The formed coil caught on the winding core20due to springback is pulled out easily from the winding core20by contracting the winding core20. After pulling out the coil from the winding core20, the winding core20is expanded so as to move the first through fourth core bars21,22,23,24back in the expanded position.

The following advantageous effects are obtained in the embodiment.

(1) In the coil winding device1, the winding core20has a column shape having the rounded first through fourth corners C1, C2, C3, C4each having a rounded cross-section. The first through fourth corners C1, C2, C3, C4have a helical continuous smooth surface extending spirally around the axis L1of the winding core20. Thus, the wire (flat wire50) is prevented from damage by the steps as described earlier with reference toFIGS. 9A and 9B. Since damage of the wire by the steps need not to be considered, the clearance between any two adjacent turns of wire in the axial direction of the winding core20is reduced and an increase of the total length of the wound coil is prevented. Therefore, damage to the wire is hardly occurred and an increase of the total length of the wound coil is prevented.
(2) The winding core20which is divided into a plurality of the first through fourth core bars21,22,23,24movable inwardly away from the wound flat wire50allows the wound wire (coil) to be removed easily from the winding core20.
(3) The winding core20according to the embodiment which is divided into four core bars21,22,23,24having the rounded first through fourth corners C1, C2, C3, C4facilitate removal of wound wire (coil) from the winding core20by replacement of the rounded first through fourth corners C1, C2, C3, C4.
(4) The first through fourth helical spaces G1, G2, G3, G4formed between the first through fourth core bars21,22,23,24extend in a helical manner. Thus, the first through fourth corners C1, C2, C3, C4are formed in a helical shape, so that the coil is easily pulled out from the winding core20.

The above embodiment may be modified in various ways as exemplified below.

In the structure for contracting the winding core20, the path of movement of the first through fourth core bars21,22,23,24is not limited to the movement in radial direction from the center of the winding core20. The first through fourth core bars21,22,23,24may be moved in any way other than radially as long as they are moved inwardly. For example, the first through fourth core bars61,62,63,64may be movable in the directions that are indicated by the double-headed arrows β inFIG. 6. Specifically, the double-headed arrows β inFIG. 6is directed obliquely with respect to an imaginary line extending radially through the center O of the winding core20.

In other words, the winding core20may be configured so that the first through fourth core bars61,62,63,64are movable inwardly so as to allow the coil to be disengaged from the winding core20and to be removed therefrom.

The provision of the helically extending first through fourth helical spaces G1, G2, G3, G4allows the first through fourth core bars61,62,63,64to be moved in the β directions other than the direction toward away from the center O (or radial direction).

According to the above embodiment, the winding core20is divided into four core bars. Furthermore, the winding core includes more than two core bars.FIG. 7shows an embodiment wherein the winding core20includes two first and second core bars71,72.

The structure for expanding and contracting the winding core20is not limited to the slide mechanism, but may be link mechanism or cam mechanism. Any structure that allows a coil to be removed from the winding core20is acceptable.FIG. 8shows an example of the link mechanism, wherein first and second core bars80,81are pivotally supported at a position adjacent to the bottom thereof by a pin90and the first and the second core bars80,81are pivoted as indicated by arrows by a cylinder95that is operative connected to the bottom of the first and the second core bars80,81through a pin91.

The wire to be wound is not limited to a flat wire, but may be any other wire, such as a wire having a circular cross-section. The winding core20or the coil is not limited to have a rectangular shape, but may have any other shape, such as a rhombus shape or any other polygonal shape.

The winding core need not be formed by a plurality of core bars, but may be formed by a single core bar.