An embodiment of the present invention relates to a wound-core production method and a wound-core production apparatus.
Recent years, for example, as a big technical trend in small distribution transformers, energy saving and efficiency improvement have been strongly promoted as exemplified by application of the so-called Top Runner Program in Japan and establishment of standards for greater efficiency improvement on a global basis. Among other things, efforts to reduce so-called “core loss,” i.e., no-load loss, which is power loss occurring in an iron core, are being made on a global scale and manufacturers are competing fiercely in an effort to improve core materials and core structures. Here, a laminated core created by laminating cut thin silicon steel sheets and a wound core created by winding cut thin silicon steel sheets are known as transformer cores. The wound core, in which magnetic flux flow in the iron core is less prone to getting obstructed, is advantageous over the laminated core from the viewpoint of core loss reduction.
For example, Patent Literature 1 discloses an example of a production method for such a wound core. Generally, this type of wound core is produced by a method such as described below. That is, while being cut turn by turn into individual windings from a thin silicon steel sheet, core material is laminated by being wound around a circular winding form. Subsequently, the wound core material annular in shape is pressed with forming dies applied to inner and outer sides of the core material, and consequently formed into the shape of a rectangular frame having an approximately rectangular aperture provided in a center. In so doing, bending stress which causes increases in core loss is produced in the core material of the wound core. Therefore, a treatment intended to relieve residual stress and restore core loss characteristics is carried out, i.e., an annealing treatment which involves heating the wound core, for example, to approximately 800 degrees C. and then cooling the wound core slowly is carried out. In addition to restoring core loss characteristics, the annealing also serves the purpose of preserving the shape of the pressed core material. Also, in assembling windings on the wound core, the wound core is opened once in a cut in each piece of the core material, and then the wound core is closed again after the windings are assembled around linear portions (legs) of the wound core.
Patent Literature 1: Japanese Patent Publication No. 5-159953
The wound-core production method described above involves winding the core material cut into individual windings around a circular winding form once, thereby forming the annular core material, and subsequently press-forming the annular core material into the shape of a rectangular frame. This involves a two-stage assembly process, making it difficult to build a continuous production line, and consequently a buffer for an intermediate product is provided in each process, resulting in increased inventories. Also, the production method requires the “winding form” used to wind the core material into an annular shape and the “forming die” used to press-form the core material into the shape of a rectangular frame, resulting in the need for production management for the purpose of storing a large number of dies/forms and supplying the dies/forms to production processes.
Thus, the present embodiment provides a wound-core production method and a wound-core production apparatus, where the production method can eliminate the conventionally required buffers for intermediate products by eliminating the need to press-form annular core material into the shape of a rectangular frame, ease production management by eliminating the need for a winding form and forming die, and thereby improve manufacturability.
The present embodiment provides a wound-core production method for winding and laminating a plurality of pieces of core material which has at least one cut in each winding and thereby producing a wound core having a rectangular aperture in a central part, the wound-core production method comprising laminating the plurality of pieces of the cut core material while winding the core material into a shape of a rectangular frame using a winding device.
Also, the present embodiment provides a wound-core production apparatus which winds and laminates a plurality of pieces of core material having at least one cut in each winding and produces a wound core having a rectangular aperture in a central part, the wound-core production apparatus comprising: a cutting device adapted to cut the core material; and a winding device adapted to laminate the plurality of pieces of the core material cut by the cutting device, while winding the core material into a shape of a rectangular frame.
An embodiment of a wound-core production method and wound-core production apparatus will be described below with reference to the drawings.
First a wound core 1 shown in
A schematic configuration of a production apparatus 10 which produces the wound core 1 is shown in
The winding device 13 includes a winding core 18, a belt 19 functioning as pressing means, and a plurality of guide rollers 20 adapted to guide movement of the belt 19. The winding core 18 includes a base 21 rotated around a rotation center O and four rollers 22 installed on the base 21. As the winding core 18 rotates around the rotation center O in the direction of arrow A in
In the winding device 13, the belt 19 is placed, surrounding outermost core material 2, and moves in the direction of arrow B in synchronization with the rotation of the winding core 18 while pressing the core material 2 being wound around the winding core 18, in a direction of the winding core 18, i.e., inward in a lamination direction, from outside. Also, rotational motion of the winding core 18 is synchronized with cutting motion of the cutting device 11, and the core material 2 sent out from the cutting device 11 is wound by the winding device 13 in sequence. As a predetermined number of pieces of core material 2 are wound around the winding core 18 in this way and laminated, the wound core 1 in the shape of a rectangular frame is formed. Note that if it is difficult to form the core material into the shape of a rectangular frame due to increases in rigidity during forming depending on thickness of the core material, a plurality of pressing rollers 23 can be placed on an outer circumference of the belt 19 and used to press the core material 2, making the forming easier.
When the winding of the core material 2 is completed, the wound core 1 is bound by the binding members 7 in a plurality of locations (see
In the winding device 13, the four rollers 22 of the winding core 18 forms the rectangular aperture 3 of the wound core 1. In this case, the four rollers 22 are configured to be movable in a longitudinal direction (see arrow C1 in
Then, the wound core 1 removed from the winding device 13 undergoes an annealing treatment in a state of being bound by the binding members 7. In the annealing treatment, the wound core 1 is heated to approximately 800 degrees C., and then cooled slowly. In assembling non-illustrated windings on the wound core 1 produced in this way, the wound core 1 is opened once in the cut 17 in each piece of the core material, and then the wound core 1 is closed again after the windings are assembled around the long-side portions 4 of the wound core 1.
In the embodiment described above, the plurality of pieces of the core material 2 cut as individual windings are laminated while being wound into the shape of a rectangular frame by the winding device 13, thereby producing the wound core 1 having the rectangular aperture 3 in the central part. Whereas the conventional production method involves winding core material cut into individual windings around a circular winding form once, thereby forming annular core material, and subsequently press-forming the annular core material into the shape of a rectangular frame, the present embodiment eliminates the need to press-form the annular core material into the shape of a rectangular frame, making it possible to improve manufacturability. Also, there is no need for a winding form used to wind the core material into an annular shape.
A cutting process of the cutting device 11 adapted to cut the core material 2 and a winding process of the winding device 13 adapted to wind the cut core material 2 are continuous with each other, making it possible to further improve the manufacturability of the wound core 1.
Since the winding device 13 includes the belt 19 as the pressing means for pressing the core material 2 wound around the winding core 18 in the lamination direction, the core material 2 can be wound properly around the winding core 18. Also, since the belt 19 is configured to move in synchronization with the rotation of the winding core 18, the core material 2 can be wound more properly around the winding core 18.
By synchronizing the rotational motion of the winding core 18 on the winding device 13 with the cutting motion of the cutting device 11, it is possible to further improve the manufacturability of the wound core 1.
Also, in any of the processes before the core material 2 is wound by the winding device 13, if a bending tendency is created by press-forming the core material 2 in such a way as to bend the core material 2, the core material 2 wound by the winding device 13 can be wound properly into the shape of a rectangular frame, making it possible to further prevent the wound core material 2 from losing its shape.
This is effective, for example, in producing a wound core 30 shaped as a rectangular frame such as shown in
The winding device 13 is configured such that the dimensions of the aperture 3 in the wound core 1 can be changed by changing the positions of the four rollers 22 of the winding core 18. This provides the advantage of being able to produce wound cores 1 differing in the dimensions of the aperture 3 using a single winding core 18.
The present embodiment has a process in which after a plurality of pieces of the core material 2 are wound into the shape of a rectangular frame by the winding device 13, the resulting wound core 1 is removed from the winding device 13 in a state of being bound by the binding members 7. Thus, by binding the wound core 1 with the binding members 7, since it is possible to keep the wound core 1 in shape, it is easy to remove the wound core 1 from the winding device 13 and the wound core 1 can easily be stored and conveyed to a next process after the removal. Since the binding members 7 has heat resistance, the annealing treatment of the wound core 1 can be carried out with the wound core 1 kept bound by the binding members 7.
The pressing means for pressing the core material 2 wound around the winding core 18 toward the winding core 18 may be made up, for example, of a plurality of rollers instead of the belt 19.
As described above, in producing a wound core having a rectangular aperture in a central part by winding and laminating a plurality of pieces of core material which has at least one cut in each winding the present embodiment eliminates the need to press-form the annular core material into the shape of a rectangular frame, and improves manufacturability.
The present embodiment is presented only by way of example, and is not intended to limit the scope of the invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. The present embodiment and modifications thereof are included in the gist and scope of the invention as well as in the invention set forth in the appended claims and the scope of equivalents thereof.
Number | Date | Country | Kind |
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2015-178484 | Sep 2015 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2016/053807 | 2/9/2016 | WO | 00 |