Patent Application
20250108428
This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2023-171984, filed on Oct. 3, 2023, the entire contents of which are incorporated herein by reference.
The present disclosure relates to a press die assembly.
Japanese Laid-Open Patent Publication No. 2018-39038 describes a die assembly for press working. The die assembly described in the publication includes a bolster, a lower die attached to the upper surface of the bolster, a slide located above the bolster and the lower die so as to be movable in the vertical direction, and an upper die attached to the lower surface of the slide. The lower die includes a cylindrical die member. The upper die includes a columnar punch configured to move into and out of the hole of the die member. The die assembly is configured to perform press working, such as drawing, on a workpiece through cooperation of the die member and the punch.
In a typical die assembly for press working such as the one described in the above publication, when the slide is moved vertically at a high speed, the top dead center and the bottom dead center of the slide vary due to inertia, so that the top dead center and the bottom dead center of the punch may vary. In addition, the relative positions of the punch of the upper die at the bottom dead center and the die hole of the lower die may change due to thermal expansion caused by an increase in the temperature of the slide or the bolster, or by thermal contraction caused by a decrease in the temperature. Therefore, the amount of entry of the punch into the die member, i.e., the amount of pressing of the punch into the workpiece, varies, which may deteriorate the machining accuracy of the workpiece.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
In a general aspect, a press die assembly configured to perform press working on a workpiece includes a lower die including a die hole, an upper die, a stripper plate, and a coupling member. The upper die is configured to be moved in a vertical direction toward and away from the lower die. The stripper plate is provided between the lower die and the upper die and is configured such that the workpiece is held between the stripper plate and the lower die. The coupling member couples the upper die and the stripper plate to each other such that the upper die and the stripper plate are movable in a vertical direction relative to each other. The upper die includes a punch, an upper die main body that accommodates an upper end portion of the punch, and an elastic member provided between the upper end portion of the punch and a portion of the upper die main body that is located above the upper end portion. The punch includes a first large-diameter portion that restricts the punch from pressing into the workpiece by contacting the stripper plate, and a second large-diameter portion that is located above the first large-diameter portion and has a diameter larger than that of the first large-diameter portion. The upper die main body includes a restricting portion that restricts the punch from moving downward by contacting the second large-diameter portion. The elastic member is configured to urge the punch toward the restricting portion and to allow the upper die main body to approach the punch by being compressively deformed in a state in which the first large-diameter portion is in contact with the stripper plate.
Other features and aspects will be apparent from the following detailed description, the drawings, and the claims.
Throughout the drawings and the detailed description, the same reference numerals refer to the same elements. The drawings may not be to scale, and the relative size, proportions, and depiction of elements in the drawings may be exaggerated for clarity, illustration, and convenience.
This description provides a comprehensive understanding of the methods, apparatuses, and/or systems described. Modifications and equivalents of the methods, apparatuses, and/or systems described are apparent to one of ordinary skill in the art. Sequences of operations are exemplary, and may be changed as apparent to one of ordinary skill in the art, with the exception of operations necessarily occurring in a certain order. Descriptions of functions and constructions that are well known to one of ordinary skill in the art may be omitted.
Exemplary embodiments may have different forms, and are not limited to the examples described. However, the examples described are thorough and complete, and convey the full scope of the disclosure to one of ordinary skill in the art.
In this specification, “at least one of A and B” should be understood to mean “only A, only B, or both A and B.”
A press die assembly according to an embodiment will now be described with reference to
First, a stator core 10 according to the present embodiment will be described with reference to
For illustrative purposes, some parts of the structures in the drawings may be exaggerated or simplified.
As shown in
In the following description, the axial direction of the stator core 10 will be referred to as a stacking direction, radial directions of the stator core 10 will simply be referred to as radial directions, and a circumferential direction of the stator core 10 will simply be referred to as a circumferential direction.
The stator core 10 includes an annular yoke 11, and multiple teeth 12 that extend radially inward from the yoke 11 and are formed at intervals in the circumferential direction.
A slot 13 is formed between any two of the teeth 12 that are adjacent to each other in the circumferential direction. The slots 13 open inward in the radial direction and extend in the radial direction.
As shown in
Any two of the iron core pieces 15 adjacent to each other in the stacking direction are coupled to each other by press-fitting projections and recesses of the tabs 16 to each other.
Next, the press die assembly 20 will be described.
The press die assembly 20 forms the tabs 16 on a workpiece W by performing press working on the workpiece W.
As shown in
The slide 91 is disposed above the bolster 90, and is configured to be moved up and down by a driving force applied by a driving device (not shown).
The lower die 21 includes a lower shoe 22, a die member 23 fixed to the upper surface of the lower shoe 22, and multiple lower end blocks 29 fixed to the upper surface of the lower shoe 22 at opposite sides of the die member 23.
The lower shoe 22 is fixed to the upper surface of the bolster 90.
The die member 23 has an upper surface 23a and a die hole 24 that opens in the upper surface 23a.
The upper die 31 includes an upper die main body 32 located above the lower die 21, and a punch 50 and an elastic member 62 accommodated in the upper die main body 32.
The upper die main body 32 includes an upper shoe 33 and a plate-shaped restricting member 45 fixed to the lower surface of the upper shoe 33. The upper die main body 32 also includes multiple upper end blocks 39 fixed to the lower surface of the upper shoe 33 at opposite sides of the restricting member 45.
The upper shoe 33 is fixed to the lower surface of the slide 91. The upper shoe 33 is configured to be moved vertically toward and away from the lower die 21 by the slide 91.
The upper shoe 33 includes an internal thread hole 34, which extends vertically through the upper shoe 33, an accommodating hole 41, which has a circular cross section and is vertically continuous with the internal thread hole 34, and multiple through-holes 42, which extend vertically through the upper shoe 33.
The inner diameter of the accommodating hole 41 is larger than that of the internal thread hole 34.
The through-holes 42 are arranged at opposite sides of the accommodating hole 41.
The restricting member 45 includes a through-hole 46, which extends vertically through the restricting member 45 and is continuous with the accommodating hole 41.
The inner diameter of the through-hole 46 is smaller than that of the accommodating hole 41. The restricting member 45 includes a restricting portion 47, which is formed by a portion that protrudes further radially inward than the inner circumferential surface of the accommodating hole 41.
The restricting member 45 also includes multiple first holes 48, which extend vertically through the restricting member 45 and are located at opposite sides of the through-hole 46, and second holes 49, which extend vertically through the restricting member 45 and are continuous with the through-holes 42.
Each first hole 48 is provided between the through-hole 46 and the corresponding second hole 49.
The inner diameter of the second holes 49 is smaller than that of the through-holes 42.
The upper end blocks 39 respectively face the lower end blocks 29 in the vertical direction. Lower ends of the upper end blocks 39 come into contact with upper ends of the lower end blocks 29, thereby restricting downward movement of the upper die 31.
The stripper plate 70 is provided between the lower die 21 and the upper die 31. The workpiece W is held between the stripper plate 70 and the upper surface 23a of the lower die 21.
The stripper plate 70 includes an insertion hole 71, which extends vertically through the stripper plate 70 and receives a punch 50 (discussed below), and multiple internal thread holes 72, which open in the upper surface of the stripper plate 70.
The coupling members 75 couple the upper die 31 and the stripper plate 70 such that the upper die 31 and the stripper plate 70 are movable in the vertical direction relative to each other.
The coupling members 75 each include an elastic member 76 and a stripper bolt 80.
The upper end of each elastic member 76 is inserted into the corresponding first hole 48 and connected to the lower surface of the upper shoe 33. The lower end of each elastic member 76 is connected to the upper surface of the stripper plate 70. The elastic members 76 of the present embodiment are coil springs.
The stripper bolts 80 each include a cylindrical spacer 81 having a flange 82 at its upper end, and a bolt 83 inserted into the spacer 81 from above.
The spacer 81 is slidably inserted into the corresponding second hole 49 from above. The lower end of the spacer 81 is in contact with the upper surface of the stripper plate 70.
The flange 82 is disposed inside the corresponding through-hole 42, and is configured to move up and down with respect to the through-hole 42.
The bolt 83 is inserted into the spacer 81 from above and screwed into the internal thread hole 72.
The punch 50 includes a support member 51, a punch main body 56, a collar 60, and a receiving member 61.
The support member 51 is tubular and has a large-diameter portion 52 at its upper end. The outer diameter of the large-diameter portion 52 is larger than the inner diameter of the through-hole 46.
The support member 51 is slidably inserted into the through-hole 46 from above.
The punch main body 56 includes a columnar main body portion 57 and a flange portion 58 provided at the upper end of the main body portion 57.
The punch main body 56 is inserted into the support member 51 from above. The lower surface of the flange portion 58 is in contact with the upper surface of the large-diameter portion 52. The lower end of the punch main body 56 protrudes downward from a lower end portion 53 of the support member 51.
When the upper die 31 is located at a top dead center, the lower end of the punch main body 56 is located above the lower surface of the stripper plate 70.
The collar 60 is disposed on the radially outer side of the flange portion 58 inside the accommodating hole 41. The receiving member 61 is provided on the upper surfaces of the flange portion 58 and the collar 60.
The elastic member 62 is disposed on the upper surface of the receiving member 61.
The elastic member 62 of the present embodiment is a coil spring.
A screw plug 35 is screwed into the internal thread hole 34 of the upper shoe 33. The elastic member 62 is provided in a state of being compressed by the lower end face of the screw plug 35 and the upper end face of the receiving member 61.
The amount of protrusion of the screw plug 35 into the accommodating hole 41 is changed to adjust the amount of compression of the elastic member 62, and thus the magnitude of the urging force that urges the punch 50 toward the restricting portion 47.
In the punch 50 of the present embodiment, the lower end portion 53 of the support member 51 has a larger diameter than the main body portion 57 of the punch main body 56.
In the present embodiment, the lower end portion 53 of the support member 51 comes into contact with the upper surface of the stripper plate 70, thereby functioning as a first large-diameter portion that restricts the punch 50 from pressing into the workpiece W.
In addition, in the present embodiment, the large-diameter portion 52 of the support member 51 comes into contact with the upper surface of the restricting portion 47 of the restricting member 45, thereby functioning as a second large-diameter portion that restricts the support member 51 from moving downward.
Operation of the present embodiment will now be described. In
As shown in
The stripper plate 70 is coupled to the upper die 31 via the coupling members 75. An upper end portion 50a of the punch 50 is accommodated in the upper die main body 32. The elastic member 62 is disposed between the upper end portion 50a of the punch 50 and a portion of the upper die main body 32 that is located above the upper end portion 50a.
Therefore, as the upper die 31 is lowered, the stripper plate 70 approaches the workpiece W, so that the workpiece W is held between the stripper plate 70 and the lower die 21 as shown in
As sequentially shown in
The upper die 31 and the stripper plate 70 are coupled to each other by the coupling members 75 such that the upper die 31 and the stripper plate 70 are movable in the vertical direction relative to each other.
Therefore, as sequentially shown in
Further, since the punch 50 is urged toward the restricting portion 47 by the elastic member 62, the punch 50 is less likely to be pushed back by the workpiece W when the punch 50 presses into the workpiece W. In the present embodiment, the magnitude of the urging force of the elastic member 62 for urging the punch 50 is set such that the punch 50 is not pushed back by the workpiece W. Thus, the punch 50 performs press working on the workpiece W.
The upper die 31 is configured such that the lower end portion 53 of the punch 50 abuts the stripper plate 70 even when the bottom dead center of the upper die 31 is at the uppermost position within the range of variation as shown in
In a case in which the bottom dead center of the upper die 31 is lower than the uppermost position in the range of variation, the elastic member 62 is compressively deformed as the bottom dead center of the upper die 31 becomes lower, thereby allowing the upper die main body 32 to approach the punch 50. Therefore, the amount of entry of the punch 50 into the die hole 24 is constant regardless of the position of the bottom dead center of the upper die 31.
In the present embodiment, the position at which the upper end block 39 comes into contact with the lower end block 29 to restrict the upper die main body 32 from approaching the lower die 21 is the lowermost position in the range of variation of the bottom dead center of the upper die 31.
The present embodiment has the following advantages.
(1) The punch 50 includes the first large-diameter portion, which restricts the punch 50 from pressing into the workpiece W by coming into contact with the stripper plate 70, and the second large-diameter portion, which is located above the first large-diameter portion and has a larger diameter than the first large-diameter portion. The upper die main body 32 includes the restricting portion 47, which restricts downward movement of the punch 50 by contacting the second large-diameter portion. The elastic member 62 is configured to urge the punch 50 toward the restricting portion 47 and to allow the upper die main body 32 to approach the punch 50 by being compressively deformed in a state in which the first large-diameter portion is in contact with the stripper plate 70.
This configuration, which operates in the above-described manner, improves the processing accuracy of the workpiece W when performing the tab forming process or the like.
(2) The support member 51 includes the first large-diameter portion at the lower end and the second large-diameter portion at the upper end. The punch main body 56 includes the main body portion 57, which is inserted into the support member 51 and protrudes further downward than the first large-diameter portion, and the flange portion 58, which is provided at the upper end of the main body portion 57 and abuts the upper surface of the support member 51.
As the press working is repeatedly performed, the tip of the punch 50, which presses the workpiece W, is worn and deformed. When the tip is worn, it is necessary to perform maintenance such as grinding the tip of the punch 50 or replacing the punch 50 with a new one.
According to the above-described configuration, the support member 51, which includes the first large-diameter portion and the second large-diameter portion, and the punch main body 56, which has the tip, are formed as separate components. Thus, when the tip is worn, only the punch main body 56 needs to be replaced with a new one. As compared to a case in which the entire punch 50 is formed integrally, the sizes of replacement parts are reduced, so that the costs required for part replacement are reduced.
(3) The press die assembly 20 is employed in an apparatus for manufacturing the stator core 10, which is formed by stacking multiple iron core pieces 15. The press die assembly 20 forms tabs 16 in each of the iron core pieces 15 using the punch 50.
According to this configuration, since the tabs 16 are formed in the iron core pieces 15 by the press die assembly 20, variations in dimensions of the tabs 16 formed in each of the iron core pieces 15 are suppressed. Therefore, when the iron core pieces 15 adjacent to each other are press-fitted to each other, the overlapped tabs 16 can be firmly fitted to each other. This increases the binding strength between the iron core pieces 15 and limits variations in the binding strength between the iron core pieces 15.
The above-described embodiment may be modified as follows. The above-described embodiment and the following modifications can be combined as long as the combined modifications remain technically consistent with each other.
The bottom dead center of the punch main body 56 is determined by the abutment of the support member 51 against the upper surface of the stripper plate 70 and the abutment of the flange portion 58 of the punch main body 56 against the large-diameter portion 52 of the support member 51. Therefore, the lower end block 29 and the upper end block 39 may be omitted.
In the above-described embodiment, the elastic members 76 and the stripper bolts 80 form the coupling members 75. However, the stripper bolts 80 may be omitted.
In the above-described embodiment, the punch 50 is formed by the support member 51 and the punch main body 56. However, the punch 50 may be formed by a single component.
The elastic member 62 is not limited to a coil spring. The elastic member 62 may be made of rubber, for example.
In the above-described embodiment, the press die assembly of the present disclosure is used to form tabs in a stator core by press working. However, the press die assembly of the present disclosure may be used to form tabs in a rotor core. Further, the press die assembly is not limited to one employed in an apparatus for manufacturing a motor core, and can be employed in apparatus for manufacturing other components.
Various changes in form and details may be made to the examples above without departing from the spirit and scope of the claims and their equivalents. The examples are for the sake of description only, and not for purposes of limitation. Descriptions of features in each example are to be considered as being applicable to similar features or aspects in other examples. Suitable results may be achieved if sequences are performed in a different order, and/or if components in a described system, architecture, device, or circuit are combined differently, and/or replaced or supplemented by other components or their equivalents. The scope of the disclosure is not defined by the detailed description, but by the claims and their equivalents. All variations within the scope of the claims and their equivalents are included in the disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-171984 | Oct 2023 | JP | national |
