The present invention relates to a cold-press molding apparatus and a cold-press molding method using the same, and further relates to a rotor core of an automobile alternating-current generator manufactured using the cold-press molding method thereof, wherein the cold-press molding apparatus can reduce burrs generated in between the backside tool without high grade lubrication films especially on molding a taper shape steel rod-like protruding material and can extend the life of the molding tool, and the cold-press molding method using the same; and further relates to a rotor core of an automobile alternating-current generator manufactured using the cold-press molding method.
It is difficult to process a taper shape steel rod-like protruding material by direct extrusion because of requirement of high processing pressure. Accordingly, in general, a preshaped material processable using relatively low processing pressure is manufactured by such as cold forging in advance and then the material is processed to obtain a taper shape processed material by ironing in the axis direction.
While such taper shape material, in general, is made by hot forging, warm forging or cold forging, it is problematic that abrasion of a mold is severe in warm forging and hot forging and stability of the shape is bad. Accordingly, in general, the shape is stabilized for use by a machine work after shaping. Further, a material having a long pawl element or an acicular shape end of the pawl element cannot be manufactured by using traditional method because of requirement of very high shaping pressure.
Further, it is possible to shape such long pawl element or an acicular shape end of the pawl element using direct cold-press forging, but it is problematic because of difficulty in requirement of very high pressure. Accordingly, an intermediate material is preshaped by such as cold forging and then the preshaped material thereof is processed to obtain a desired shape.
The important thing in such ironing processing is to prevent baking and galling between a tool and a processed material because it is a slide processing in which the ironing tool and the steel processed material contact directly under high pressure. Accordingly, high grade lubrication films such as phosphate films must be made on the surface of the processed material.
Referring to Figure, 31a is a processed material before ironing shaping, 31b is a processed material after ironing shaping, 32 is a backside tool (mandrel), 33 is a ironing die and 34 is a burr occurred between the backside tool (mandrel) and the processed material.
As described above, as well as mandatorily better lubrication films on the surface of the processed material in the cold-press shaping by slide-press, and variation of quality should be minified.
Further, for example, as described in Patent Document 1, a means to lower the friction coefficient between the surface of the shaping tool and the processed material by coating the surface of the shaping tool with rigid films is required to extend the life of the shaping tool, e.g. an ironing tool.
Patent Document: Laid Open JP 2003-112229
However, there were the following problems in the traditional cold-press shaping method. (1) If variation of quality of lubrication films occurs, the pressure to the backside tool (mandrel) varies and variation of the backside shapes may be caused, and homogeneous lubrication films are mandatory, accordingly. (2) Further, in this method, it is problematic that the result due to variation of quality severely depends on the right-or-wrong quality of the lubrication films, and if unsatisfactory lubrication films are used, unsatisfactory shaping of the backside likely result from that the increased friction results in plastic flow of the processed material largely occurs due to frication holding and the burr occurred in between the backside tool (mandrel) should be large. (3) It is not avoidable that the burr in between the backside tool (mandrel) occurs somewhat because the ironing tool slides on the surface of the processed material under high pressure. Further, it is problematic that an effect on the life of the tool must be considered because a load should occur on the ironing tool as well.
Accordingly, the purpose of the present invention is to provide a cold-press molding apparatus that can reduce burrs generated in between the backside tool without high grade lubrication films on molding a taper shape steel rod-like protruding material, can carry out shaping of the backside tool in better way, and can extend the life of the molding tool; and
A cold-press molding apparatus of the present invention to make a taper shape steel rod-like protruding material and to achieve the above purposes is characterized by a preshaped processed material,
In the above constitution, the preshaping of the processed material is preferably conducted by cold forging, warm or hot forging.
A cold press molding method of the present invention to make a taper shape steel rod-like protruding material and to achieve the above purposes is characterized by holding the processed material preshaped processed material on a backside tool, rolling the free rotation roll freely rolling toward the tip element while press-contacting on the processed material and shaping a taper shape by plastic-reshaping of the processed material.
In the above constitution, the preshaping of the processed material is preferably conducted by cold forging, warm or hot forging.
Further, the present invention to achieve the above purposes provides a rotor core manufactured by the above cold-press molding method and is characterized thereby.
As described above, according to the present invention, given holding the processed material preshaped processed material on a backside tool (mandrel), rolling the free rotation roll freely rolling toward the tip element while press-contacting to the processed material and shaping a taper shape by plastic-reshaping of the processed material, the shaping can be conducted at lower temperature because generated processing heat is transferred to the rotating roll, no high grade lubricant is required and further, an effect of variation of lubricants can be little.
In addition, since a maximum load on shaping is mostly linear load, load can be used more efficiently and further thermal expansion of the tool becomes less because temperature rising is suppressed by thermal transfer to the roll so that occurrence of burr on the pressed surface can be less and the shaping of the backside element can be conducted with sufficient precision. Further, the life of the shaping tool can be extended because the load on the shaping tool is less.
Further, given using the cold-press molding apparatus of the present invention, because the cold-press molding can be easily conducted according to the constitution thereof, a taper shape steel rod-like protruding material can be cold-press-molded without high grade lubrication films, with reducing burrs generated in between the backside tool and further with better shaping of the backside element, and the life of the apparatus per se can be extended as well.
Further, as for a rotor core (rotator) of an automobile alternating-current generator, the structure having long-pawl or a sharp angle tip, which is difficult to be made using the traditional shaping method, can be easily and effectively made at low cost.
According to Embodiment of the present invention, referring to Figs., the inventors illustrates detail of a cold-press molding apparatus, a method of cold-press molding using the same, and a rotor core of an automobile alternating-current generator manufactured using the cold-press molding method thereof.
Specifically, on processed material 31 (31a, 31b) held by a backside tool (mandrel) 32, while a free rotation roll 41 freely rotating is being press-contacted, the free rotation roll 41 is rolled toward the taper shaped tip element of the pawl element 11, and the processed material 31 (31a, 31b) is plastic-reshaped by the rolling to shape the taper shape shown in
According to such rolling press, as the free rotation roll 41 is contacting the surface of the processed material 31 (31a 31b) while rolling, almost no relative slide between the free rotation roll 41 and the processed material 31 exists, the relative friction is less and the processing temperature can be suppressed by heat transfer. Further, processing temperature can be controlled by adjusting e.g. the size and rotation rate of the free rotation roll 41 and cooling of the roll. Accordingly, a lubricant such as high grade phosphate film on the surface of the processed material 31 (31a, 31b) is not needed and further, an effect of variation of lubrication property of the lubricant is less.
Accordingly, because variation of pressure on the backside tool (mandrel) 32 becomes less, occurrence of variation of backside shape is less, and further less burr 34 occurs. Accordingly, it is easy to remove the burr 34 and the lesser burr 34 occurs, the lower material loss.
Further, the contact pressure load for the free rotation roll 41 is lesser than the ironing die therefor as a shaping tool so that the life of the free rotation roll 41 as a ironing tool can be longer than the ironing die.
As described above, slide between the free rotation roll 41 and the surface of the processed material 31 (31a, 31b) is almost none and the friction decreases so that the high grade metal hardening layer on the surface thereof is unnecessary to be installed. Further, accordingly, use of such as mechanical oil can be satisfactory on the surface of the processed material 31 (31a, 31b).
As described above, according to the present Embodiment, given holding the preshaped processed material on a backside tool (mandrel), rolling the free rotation roll toward the tip element while press-contacting the processed material and shaping a taper shape by plastic-reshaping of the processed material, no high grade lubricant is needed and further, an effect of variation of lubricants can be little. Further, the load is changed from surface load to linear load so that the transmission efficiency of the load can be improved.
A production of a rotor core of an automobile alternating-current generator, of which the structure has a long-pawl or a sharp angle tip, which is difficult to be made using the traditional shaping method, has become possible by using this method. Accordingly, the less burr on the pressed surface occurs so that the shaping of the backside element can be conducted with satisfactory precision. Further, the life of the shaping tool can be extended because the load on the shaping tool is less.
Further, according to the above Embodiment, preshaping of the processed material 31 is illustrated based on Embodiment of cold forging, but it is not limited and warm forging and hot forging can be used.
Since the present invention comprising the above constituent can be implemented as described above so that taper shape steel rod-like protruding material can be relatively easily processed, and can be applied in a variety of productions of machines having complicated structure including a motor, a generator, an automobile, a vehicle, a combustion engine, a printing machine, a paper making machine, a yarn-making machine, and a loom.
10 Rotor core
11 Pawl element
12 Intermediate material
13 Pawl element equivalent
14 Pulling apparatus
31, 31a, 31b Processed material
32 Backside tool (mandrel)
33 Ironing die
34 Burr
41 Free rotation roll
Number | Date | Country | Kind |
---|---|---|---|
2012-177571 | Aug 2012 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/JP2013/071685 | 8/9/2013 | WO | 00 | 11/25/2013 |