Patent Publication Number: US-2020290106-A1

Title: Stamping method and stamping apparatus

Description:
BACKGROUND 
     1. Field 
     The following description relates to a stamping method and a stamping apparatus. 
     2. Description of Related Art 
     Conventionally, fine blanking has been known as a method of punching out a product from a plate-shaped workpiece using a die and a punch. In fine blanking, a plate holding member, a die, a punch, and a back-up member, which is provided inside the die, are used. Specifically, the opposite sides of a workpiece are held by the die and the plate holding member, and a product is punched out from the workpiece using the die and the punch while the workpiece is held from the side opposite to the punch by the back-up member. 
     Japanese Laid-Open Patent Publication No. 2005-262294 discloses an apparatus that takes out a product to the outside from a fine blanking press. The apparatus of the publication includes a nozzle for drawing in air and uses the nozzle to apply suction to the product, thereby ejecting the product to the outside. 
     Since the apparatus of the above-described publication is required to have a nozzle to eject the punched product, the structure of the apparatus as a whole is complicated. 
     SUMMARY 
     It is an objective of the present disclosure to provide a stamping method and a stamping apparatus that are capable of ejecting products using a simple structure. 
     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 stamping method for punching out a product from a workpiece that is conveyed intermittently is provided. The method includes: punching out the product from the workpiece by using a die on which the conveyed workpiece is placed, a punch that is arranged to approach and move away from the die, and a back pressure portion that is provided in the die and is urged toward the punch to apply a back pressure to the workpiece; displacing the workpiece upward with respect to the die when the punch moves away from the die; before the product is punched out, providing a protrusion that protrudes downward and is located at a part of the workpiece, wherein the part is on an upstream side in a workpiece conveying direction of a punch-out portion, from which the product is punched out, and is aligned with the punch-out portion; and using the protrusion, which is displaced downstream in the conveying direction together with the workpiece, to push the product downstream in the conveying direction, so that the product is ejected to the outside. 
     In another general aspect, a stamping apparatus for punching out a product from a workpiece that is conveyed intermittently is provided. The apparatus includes a punch-out mechanism, a protrusion providing mechanism, and a displacing mechanism. The punch-out mechanism includes a die on which the conveyed workpiece is placed, a punch that is arranged to approach and move away from the die, and a back pressure portion that is provided in the die and is urged toward the punch to apply a back pressure to the workpiece. The punch-out mechanism is configured to punch out the product from the workpiece by using the die, the punch, and the back pressure portion. The protrusion providing mechanism is configured to provide a protrusion that protrudes downward and is located at a part of the workpiece. The part is on an upstream side in a workpiece conveying direction of a punch-out portion, from which the product is punched out, and is aligned with the punch-out portion. The displacing mechanism is configured to displace the workpiece to a position where the protrusion and the product are aligned with each other in the conveying direction when the punch moves away from the die. 
     Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of a stamping method and a stamping apparatus according to one embodiment, illustrating the structure of the stamping apparatus. 
         FIG. 2  is a plan view of a workpiece illustrating protrusions of the embodiment together with a punch-out portion. 
         FIG. 3  is a cross-sectional view of the stamping method of the embodiment, illustrating a state in which the workpiece has been conveyed to a protrusion providing mechanism. 
         FIG. 4  is a cross-sectional view of the stamping method of the embodiment, illustrating a state in which protrusions have been provided on the workpiece. 
         FIG. 5  is a cross-sectional view of the stamping method of the embodiment, illustrating a state in which the workpiece has been conveyed to a punch-out mechanism. 
         FIG. 6  is a cross-sectional view of the stamping method of the embodiment, illustrating a state in which the workpiece is held by a second lower die assembly and a second upper die assembly. 
         FIG. 7  is a cross-sectional view of the stamping method of the embodiment, illustrating a state in which a product has been punched out from the workpiece by a second punch. 
         FIG. 8  is a cross-sectional view of the stamping method of the embodiment, illustrating a state in which the product is lifted by a back pressure portion. 
         FIG. 9  is a cross-sectional view of the stamping method of the embodiment, illustrating a state in which the product is being pushed toward an ejection portion by protrusions. 
         FIG. 10  is a plan view of a workpiece illustrating a protrusion of a modification together with a punch-out portion. 
     
    
    
     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. 
     DETAILED DESCRIPTION 
     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. 
     A stamping method and a stamping apparatus  10  according to an embodiment will be described with reference to  FIGS. 1 to 9 . 
     The stamping apparatus  10  of the present embodiment is employed in a progressive stamping apparatus, which is configured to subject a plate-shaped workpiece, which is intermittently conveyed by a feeder (not shown), to multiple steps such as a piercing step and a punching-out step in a single apparatus. 
     As shown in  FIG. 1 , the stamping apparatus  10  is designed to punch out a product P from a workpiece  100 , which is conveyed from left to right in  FIG. 1 . The product P of the present embodiment is a gear having teeth on the outer circumference. Hereinafter, the conveying direction of the workpiece  100  will be simply referred to as conveying direction Y, and the upstream side and the downstream side of the conveying direction Y will be referred to as the upstream side and the downstream side. A direction that is orthogonal to both the conveying direction Y and the vertical direction will be referred to as a width direction. 
     The stamping apparatus  10  includes a protrusion providing mechanism  20 , a punch-out mechanism  50 , and a displacing mechanism  90 . The protrusion providing mechanism  20  is configured to provide downward protrusions  101  in the workpiece  100 . The punch-out mechanism  50  is provided on the downstream side of the protrusion providing mechanism  20  and is configured to punch out the product P from the workpiece  100 . The displacing mechanism  90  is configured to displace the workpiece  100  upward. 
     First, the protrusion providing mechanism  20  will be described. 
     The protrusion providing mechanism  20  includes a first lower die assembly  30 , which has two first dies  31 , and a first upper die assembly  40 , which has two first punches  41 . The conveyed workpiece  100  is placed on the first dies  31 . The first punches  41  are arranged to approach and move away from the first dies  31  in the vertical direction. The first upper die assembly  40  is arranged to approach and move away from the first lower die assembly  30 . 
     Each first punch  41  has a circular shape in the cross section orthogonal to the vertical direction. 
     The first upper die assembly  40  has recesses in the lower surface. The recesses receive two first holding members  42 , which hold the workpiece  100  against the first dies  31 . The first punches  41  are arranged to be projected from and retracted into the lower surfaces of the first holding members  42 . 
     When the first punches  41  are lowered toward the first dies  31 , two protrusions  101  each having a circular cross section are provided in the workpiece  100 . The protrusions  101  of the present embodiment are dowels that are protruded downward by performing half-blanking on the workpiece  100 . The protruding amount of the protrusions  101  from the lower surface of the workpiece  100  (hereinafter, simply referred to as the protruding amount) is smaller than the thickness of the workpiece  100 . 
     The two first dies  31  are spaced apart from each other in a width direction X. The two first punches  41  and the two holding members  42  correspond to the two first dies  31 . 
     Accordingly, the two protrusions  101  of the workpiece  100  are spaced apart from each other in the width direction X as shown in  FIG. 2 . The workpiece  100  has a punch-out portion  102 , from which the product P will be punched out. The protrusions  101  are provided in a part that is on the upstream side of the punch-out portion  102  and aligned with the punch-out portion  102 . The protrusions  101  are provided at positions that correspond to the opposite sides of the punch-out portion  102  in the width direction X. The protrusions  101  are provided in a feed bridge of the workpiece  100 , which connects the punch-out portion  102  to the subsequent punch-out portion  102 , which will be punched out after the first punch-out portion  102 . 
     In this manner, the workpiece  100 , on which the protrusions  101  are provided, is conveyed to the punch-out mechanism  50 , which is located on the downstream side of the protrusion providing mechanism  20 . 
     The punch-out mechanism  50  will now be described. 
     As shown in  FIG. 1 , the punch-out mechanism  50  includes a second lower die assembly  60 , which has a second die  61 , and a second upper die assembly  70 , which has a second punch  71 . The workpiece  100  is placed on the second die  61 . The second punch  71  is arranged to approach and move away from the second die  61 . The second upper die assembly  70  is arranged to approach and move away from the second lower die assembly  60 . The second die  61  has a gear forming portion on the inner circumferential surface, and the second punch  71  has a gear forming portion on the outer circumferential surface. The second die  61  corresponds to the die of the present disclosure. The second punch  71  corresponds to the punch of the present disclosure. 
     The second die  61  incorporates a back pressure portion  80 , which is urged toward the second punch  71  to apply a back pressure to the workpiece  100 . The back pressure portion  80  includes a pushing member  81 , which pushes the workpiece  100  from below, and an urging portion  82 , which urges the pushing member  81  upward. In a state in which the pushing member  81  is not pushed by the second punch  71 , the upper surface of the pushing member  81  and the upper surface of the second die  61  are flush with each other. The pushing member  81  has a gear forming portion on the outer circumferential surface. 
     The urging portion  82  of the present embodiment may be a gas cylinder unit that includes, for example, a cylinder and a piston rod that is reciprocal in the cylinder. 
     The second upper die assembly  70  has a recess in the lower surface. The recess receives a second holding member  72 , which holds the workpiece  100  against the second die  61 . The second punch  71  is arranged to be projected from and retracted into the lower surface of the second holding member  72 . 
     The displacing mechanism  90  will now be described. 
     The displacing mechanism  90  is provided in a part of the second lower die assembly  60  that is on the upstream side of the second die  61 , and is configured to displace the workpiece  100  upward with respect to the second die  61 . Specifically, the displacing mechanism  90  is provided in an accommodating portion  62 , which is provided in the second lower die assembly  60  and is open upward. The displacing mechanism  90  includes a clamp portion  91 , which clamps the workpiece  100  in the vertical direction, and a compression spring  92 , which is provided in the accommodating portion  62  to urge the clamp portion  91  upward. 
     Escape portions  63 , which open upward, are provided in a part of the upper surface of the second lower die assembly  60  that is between the displacing mechanism  90  and the second die  61  in the conveying direction Y. The escape portions  63  are designed to allow the protrusions  101  of the workpiece  100  to escape into when the workpiece  100  is punched out, such that the workpiece  100  is placed along the upper surface of the second lower die assembly  60 . The depth of the escape portions  63  is greater than the protruding amount of the protrusions  101 . 
     An accommodating portion  73 , which opens downward, is provided in a part of the lower surface of the second upper die assembly  70  that is on the upstream side of the second holding member  72 . The accommodating portion  73  is designed to accommodate the upper part of the clamp portion  91  of the displacing mechanism  90  when the second lower die assembly  60  and the second upper die assembly  70  are clamped. 
     The second lower die assembly  60  has an ejection portion  64  in a part that is on the downstream side of the second die  61 . The ejection portion  64  ejects the product P, which has been punched out by the second punch  71 , to the outside of the second lower die assembly  60 . The ejection portion  64  is a through-hole that has a diameter larger than the diameter of the product P and extends vertically through the second lower die assembly  60 . 
     The stamping method of punching out the product P from the workpiece  100  using the stamping apparatus  10  will now be described. 
     First, as shown in  FIG. 3 , the workpiece  100  is conveyed to the protrusion providing mechanism  20  by a feeder, such that the workpiece  100  is placed on the first dies  31 . 
     As shown in  FIG. 4 , the workpiece  100  is held between the first lower die assembly  30  and the first upper die assembly  40 . Then, the first punches  41  are lowered to perform half-blanking on the workpiece  100  to provide the protrusions  101  (protrusion providing step). 
     As shown in  FIG. 5 , the workpiece  100 , on which the protrusions  101  are provided, is conveyed to the punch-out mechanism  50 . At this time, the workpiece  100  is conveyed such that the protrusions  101  are located at positions directly above the escape portions  63  of the second lower die assembly  60 . 
     Next, the second upper die assembly  70  is lowered as shown in  FIG. 6 , so that the workpiece  100  is held by the second lower die assembly  60  and the second upper die assembly  70 . At this time, the upper part of the clamp portion  91  of the displacing mechanism  90  is accommodated in the accommodating portion  73  of the second upper die assembly  70 . The clamp portion  91  is pushed by the second upper die assembly  70  so as to be displaced downward. Also, the protrusions  101  of the workpiece  100  are accommodated in the escape portions  63  of the second lower die assembly  60 . Accordingly, the workpiece  100  is placed on the second die  61  while being in accordance with the upper surface of the second lower die assembly  60 . 
     Next, the second punch  71  is lowered as shown in  FIG. 7 , so that the second die  61 , the second punch  71 , and the back pressure portion  80  punch out the product P from the workpiece  100  (punching-out step). 
     Next, the second punch  71  is moved away from the second die  61  and the second upper die assembly  70  is lifted as shown in  FIG. 8 . At the same time, the displacing mechanism  90  displaces the workpiece  100 , from which the product P has been punched out, upward with respect to the second die  61  (displacing step). 
     The displacing mechanism  90  displaces the workpiece  100  upward to a position where the protrusions  101  are aligned with the product P in the conveying direction Y. The amount by which the workpiece  100  is displaced from the upper surface of the second lower die assembly  60  by the displacing mechanism  90  is greater than the thickness of the product P and smaller than the sum of the thickness of the product P and the protruding amount of the protrusions  101 . In the present embodiment, the workpiece  100  is displaced upward to a position where a small clearance exists between the lower surface of the workpiece  100  and the upper surface of the product P. Thus, the displacement amount is the sum of the thickness of the product P and the clearance. 
     The product P remains on the pushing member  81  in a state in which the workpiece  100  has been displaced upward by the displacing mechanism  90 . 
     When the workpiece  100  is conveyed further as shown in  FIG. 9 , the protrusions  101  are displaced downstream in the conveying direction together with the workpiece  100 . The protrusions  101  are caused to abut against the upstream end of the product P, so that the product P is pushed downstream. Accordingly, the product P is ejected to the outside through the ejection portion  64  (ejection step). 
     As described above, the product P is produced from the workpiece  100 . 
     The operation and advantages of the present embodiment will now be described. 
     (1) In the punching-out step, the product P is punched out from the workpiece  100  by the second die  61 , on which the conveyed workpiece  100  is placed, the second punch  71 , which is arranged to approach and move away from the second die  61 , and the back pressure portion  80 , which is provided in the second die  61  and is urged toward the second punch  71  to apply a back pressure to the workpiece  100 . In the displacement step, the workpiece  100  is displaced upward with respect to the second die  61  when the second punch  71  moves away from the second die  61 . In the protrusion providing step, the protrusions  101 , which protrude downward, are provided prior to the punching-out step. The protrusions  101  are located in a part that is on the upstream side in the conveying direction Y of the workpiece  100  of the punch-out portion  102 , from which the product P will be punched out. The part is also aligned with the punch-out portion  102 . In the ejection step, the protrusions  101 , which are displaced downstream in the conveying direction Y together with the workpiece  100 , push the product P downstream in the conveying direction Y, so that the product P is ejected to the outside. 
     With this method, the product P, which has been punched out by the second die  61 , the second punch  71 , and the back pressure portion  80 , remains on the back pressure portion  80 . The workpiece  100  is displaced upward with respect to the second die  61  when the second punch  71  moves away from the second die  61 . With the above-described method, the protrusions  101 , which protrude downward, are provided in the workpiece  100  before the product P is punched out. Accordingly, the product P on the back pressure portion  80  is pushed downstream in the conveying direction Y by the protrusions  101  as the workpiece  100  is conveyed, so that the product P is ejected to the outside. Since the above-described method ejects the product P to the outside by utilizing the conveyance of the workpiece  100 , no additional devices for ejecting the product P to the outside are needed. The product P is ejected to the outside by a simple method. 
     In a case of a configuration that includes a device for ejecting products P to the outside, the ejection step of a product P is completed before the workpiece is conveyed for the punching-out step of the subsequent product P. This extends the manufacturing time by the amount of time corresponding to the ejection step of the product P. 
     In this regard, the above-described method ejects the product P as the workpiece  100  is conveyed before the subsequent product P is punched out. This shortens the time required for the stamping process. The productivity of the stamping process is thus improved. 
     (2) Half-blanking is performed on the workpiece  100  to provide the protrusions  101 . 
     When, for example, magnets that are separate from the workpiece  100  are provided as protrusions on the lower surface of the workpiece  100 , an operation for retrieving the magnets may be necessary. 
     In this regard, the above-described method does not require such an operation since the protrusions  101  are provided integrally with the workpiece  100 . This improves the productivity of the stamping process. 
     (3) The protrusions  101  are provided at positions that correspond to the opposite sides of the punch-out portion  102  in the width direction X. 
     With this method, as the workpiece  100  is conveyed, the protrusions  101 , which are provided at positions corresponding to the opposite sides in the width direction X of the punch-out portion  102 , push the opposite sides in the width direction X of the product P. The product P is thus ejected in a reliable manner. 
     (4) The stamping apparatus  10  includes the punch-out mechanism  50 , the protrusion providing mechanism  20 , and the displacing mechanism  90 . The punch-out mechanism  50  includes the second die  61 , on which the conveyed workpiece  100  is placed, the second punch  71 , which is arranged to approach and move away from the second die  61 , and the back pressure portion  80 , which is provided in the second die  61  and is urged toward the second punch  71  to apply a back pressure to the workpiece  100 . The punch-out mechanism  50  is configured to punch out the product P from the workpiece  100  by using the second die  61 , the second punch  71 , and the back pressure portion  80 . The protrusion providing mechanism  20  is configured to provide the protrusions  101 , which protrude downward, in a part that is located on the upstream side in the conveying direction Y of the workpiece  100  of the punch-out portion  102  of the workpiece  100 , from which the product P will be punched out. The part is aligned with the punch-out portion  102 . The displacing mechanism  90  is configured to displace the workpiece  100  to a position where the protrusions  101  and the product P overlap with each other in the vertical direction when the second punch  71  moves away from the second die  61 . 
     This configuration achieves an operational advantage similar to the above-described operational advantage (1). 
     The present embodiment may be modified as follows. The present embodiment and the following modifications can be combined as long as the combined modifications remain technically consistent with each other. 
     The ejection portion  64  may be a belt conveyor that conveys the product P to the outside. 
     The pushing member  81  may incorporate a lifter that is urged toward the second punch  71  and lifts the product P above the upper surface of the pushing member  81  in the displacement step. In this case, since the pushing member  81  is prevented from closely contacting the product P, the product P is easily ejected. At this time, the amount by which the workpiece  100  is displaced from the upper surface of the second lower die assembly  60  by the displacing mechanism  90  simply needs to be greater than the sum of the thickness of the product P and the protruding amount of the lifter from the upper surface of the second lower die assembly  60  and smaller than the sum of the thickness of the product P, the protruding amount of the lifter from the upper surface of the second lower die assembly  60 , and the protruding amount of the protrusions  101 . 
     Two or more displacing mechanisms  90  may be provided on the upstream side and the downstream side of the second die  61  as necessary. 
     The number, the shape, and the arrangement of the protrusions  101  may be changed in accordance with the shape of the product P as necessary. For example, as shown in  FIG. 10 , instead of multiple protrusions  101 , a single protrusion  103 , which extends along the circumferential direction of the punch-out portion  102  may be provided on the upstream side of the punch-out portion  102  and at a position aligned with the center in the width direction X of the punch-out portion  102 . 
     The protrusions are not limited to the ones that are provided by performing half-blanking on the workpiece  100 . The protrusions may be provided through burring. The protrusions may be provided on the workpiece  100  by attaching magnets on the lower surface of the workpiece  100 . 
     The range in application of the stamping apparatus  10  is not limited to the product P, which has gear teeth on the outer circumference. The stamping apparatus  10  of the present embodiment can be employed in producing products having various shapes as long as those are punched out of a plate-shaped workpiece. 
     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.