Patent Publication Number: US-2003226388-A1

Title: Rotary drive apparatus for rotary body

Description:
BACKGROUND OF THE INVENTION  
       [0001] The present invention relates to a rotary drive apparatus for a rotary body; more specifically, the present invention relates to, for example, a rotary-cam driven apparatus for a negative-angle formation die used to form a thin metallic sheet. The “negative-angle forming die” refers to a die for performing intrusive forming of a work of the material such as to be intruded into a lower die from a linear descendent locus of an upper die.  
       [0002] According to a conventional method, intrusive forming for a work of a thin metallic sheet is performed in the following manner. A work is first set on a lower die, an upper die is then vertically moved downward, a passive cam of a lower die is driven using an active cam of an upper die, and the work is transversely processed. Subsequently, after the processing has been completed and the upper die has been moved up, the active cam is retracted using a spring.  
       [0003] In the conventional method, a forming portion of the aforementioned passive cam is operated to slide in the transverse direction from the outside of the work to performing the forming process of the work. The forming portion of the passive cam is formed to have an integral shape that is the same as the shape of a forming portion of the work. However, since the work needs to be taken out from the lower die upon completion of the forming process, the forming portion of the lower die on which the work is mounted needs to be retracted by separating an intruding portion of the lower die. Alternatively, the forming portion needs to be formed to enable the work to be taken out in such a way that a rear portion of the intruding portion is preliminarily removed and the work is moved forward. Although the problem is not so serious when the extent of intrusion is minor, it becomes a serious when the intrusion extent is large and depending upon the type of the work. For example, suppose a long and slender frame-like vehicle component having a grooved section, such as a front pillar outer formed of a thin metallic sheet, is processed as a work. In this case, since the width of the grooved portion is small, when the intruding portion of the lower die is separated or removed, the component cannot be neatly formed in a desired shape; and in addition, since the strength of the lower die is not sufficient, the intrusive forming cannot be performed.  
       [0004] In addition, there are cases in which defective portions such as torsional and/or warped portions are formed in products, and correction needs to be performed therefor. However, cases occur in which even correction is practically impossible. For example, correction is practically impossible for defective portions formed on components constituting outer panel portions of a vehicle, such as a side panel, a fender, a roof, a bonnet, a trunk lid, a door panel, and a front pillar outer that have three-dimensional curved surfaces and curved lines. In assembling a product of a thin metallic sheet for a vehicle, when the product has defective portions such as torsions or warps, the product cannot be coupled to other components. Consequently, a high-quality vehicle-dedicated structure of a thin metallic sheet cannot be provided, and a predetermined product accuracy cannot be maintained for a product formed of a thin metallic sheet.  
       [0005] To solve the above-described problems, a negative-angle forming die having a configuration as described below has been proposed. In the configuration, a forming portion intruded into a lower die from a linear descendent locus of an upper die is formed, and a rotary cam is then rotationally retracted to be in a state where a formed work can be taken out from a lower die.  
       [0006] Referring to FIGS.  11  to  16 , the negative-angle forming die includes a lower die  102  for mounting a work W of a thin metallic sheet onto a supporting portion  101 , and an upper die  103  that is descended in a linear direction towards the lower die  102  for forming the work W by hitting against the work W. In addition, the negative-angle forming die further includes a rotary cam  106  provided on the lower die  102  to be rotatable. The rotary cam  106  includes a groove  104  that is open to an outer peripheral surface and that is carved along an axial direction, and an intrusive-forming portion  105  that is formed at an edge portion of the groove  104  which is closer to the supporting portion  101  and that is intruded from a locus of the upper die  103 . In addition, the negative-angle forming die includes a slide cam  108  that includes an intrusive-forming portion  107  and that is provided to the upper die  103  to be slidable in opposition to the rotary cam  106 ; and an air cylinder  109  provided to the lower die  102  for rotationally retracting the rotary cam  106  to be in a state where the work W can be taken out from the lower die  102  upon completion of the forming process. In this configuration, the work W set on the supporting portion  101  of the lower die  102  is formed using the intrusive forming portion  105  of the rotary cam  106  and the intrusive forming portion  107  of the slide cam  108 . In this case, the slide cam  108  slides to perform the forming process of the work W; and upon completion of the forming process, the rotary cam  106  is rotationally retracted using the air cylinder  109  to enable the formed work W to be taken out from the lower die  102 .  
       [0007] Hereinbelow, operations of the negative-angle forming die will be described.  
       [0008] First, as shown in FIG. 11, the upper die  103  is positioned at a top dead center, and the work W is mounted onto the supporting portion  101  of the lower die  102 . At this time, the rotary cam  106  is brought into a state of being retracted by the air cylinder  109 .  
       [0009] Subsequently, as shown in FIG. 12, the rotary cam  106  is brought into a state of being retracted by the air cylinder  109 . The upper die  103  starts to descend, and a pad  110  presses the work W mounted onto the supporting portion  101  of the lower die  102 .  
       [0010] Then, the upper die  103  descends, and as shown in FIG. 13, the lower face of the slide cam  108  engages a rotating plate  111 . At this time, the slide com  108  operates without interfering with the intrusive-forming portion  105  of the rotary cam  106 .  
       [0011] When the upper die  103  continues to descend, the slide cam  108  in the state of being urged outwardly of the die is transversely moved by the cam operation to the left in opposition to an urged force of a coiled spring  112 . Thereby, the slide cam  108  is brought into a state shown in FIG. 14, whereby intrusive forming of the work W is performed through the intrusive-forming portion  105  of the rotated rotary cam  106  and the intrusive-forming portion  107  of the slide cam  108 .  
       [0012] After the intrusive forming has been completed as shown in FIG. 15, the upper die  103  starts to move up.  
       [0013] The slide cam  108  outwardly urged by the coiled spring  112  is moved rightward in FIG. 16, the slide cam  108  rises without interfering with the work W.  
       [0014] The slide cam  108  thus rises, the rotary cam  106  rotates rightward according to the air cylinder  109 , as shown in FIG. 16, and the work W intrusively formed is then taken out from the lower die  102 . At this time, the work W can be taken out without causing interference with the intrusive-forming portion  105  of the rotary cam  106 .  
       [0015] As described above, the air cylinder is required to rotationally return the rotary cam to enable the formed work to be take out after completion of the intrusive forming.  
       [0016] Hereinbelow, referring to FIGS.  17  to  20 , a description will be made regarding a rotary-cam driven apparatus for a negative-angle forming die by way of an example of the rotary drive apparatus for the negative-angle forming die.  
       [0017] A rotary cam  5  is rotatably disposed in a lower die  1 . A cylinder  51  for returning the rotary cam  5  is disposed in the lower die  1 . A cam follower arm  52  is mounted to the rotary cam  5 . A planar driver  53  for controlling the cam follower arm  52  is provided in an upper die  3 .  
       [0018] Supporting axes  11  are individually protrudedly provided to two ends of the axial rotary cam  5 . The supporting axis  11  is internally fitted to a metal  12  of a bearing  13  (to which the cylindrical metal  12  is fixed) to be rotatable, thereby enabling the rotary cam  5  to rotate. A base plate  14  of the supporting axis  11  is fixed with a bolt to an axial end of the rotary cam  5 . The bearing  13  for receiving the supporting axis  11  is fixed with a bolt  16  to the lower die  1 .  
       [0019] An end portion  11   a  of the supporting axis  11  is formed as a square column to thereby enable the output of the air cylinder  51  to be securely transferred to the rotary cam  5 .  
       [0020] The cam follower arm  52  protrudes from a disc portion, is formed of two members, receives the end portion  11   a  of the supporting axis  11  in the center, and is connected with bolts  54 . A cam follower  55  is rotatably provided to one of the ends of the cam follower arm  52 , and is fixed with a nut  56  to prevent detachment. The other end of the cam follower arm  52  is connected to the end of a piston rod.  57  of the cylinder  51  with a pin  59  via a connecting member  58 . A threaded rod portion  67  of the end of the piston rod  57  is inserted into a connecting member  58 , a nut  68  threaded on the threaded rod portion  67  is tightened to thereby connect the connecting member  58  and the end of the piston rod  57 . Because of variations in the amount of tightening the nut  68 , a rotation start position and a rotation termination position of the cam follower arm is not precisely determined. As such, in a state where the rotary cam  5  cannot be accurately disposed, intrusive forming is performed, thereby disabling the implementation of high-quality work processes. The cylinder  51  is fixed to the lower die  1  with a bolt  61  via a bracket  60 .  
       [0021] Ordinarily, the piston rod  57  of the cylinder  51  extends to thereby maintain the forming posture; and after the upper die  3  descends and intrusive forming is completed, the piston rod  57  retracts, and the rotary cam  5  rotationally retracts. Then, the work becomes ready to be taken out upwardly.  
       [0022] If the cylinder  51  malfunctions, the driver  53  of the upper die  3  and the cam follower arm  52  of the lower die  1  cause the rotary cam  5  to assume, for example, the forming posture and a posture enabling the rotationally retracted work to be taken out upwardly.  
       [0023] Specifically, the planar driver  53  is provided in a portion opposing the cam follower arm  52  of the upper die  3 . The rotation of the rotary cam  5  is controlled by causing the cam follower  55  of the cam follower arm  52  to engage a cam face  62  of the driver  53 . The cam face  62  is determined in consideration regarding the position where the rotary cam  5  is rotated during a descending stroke of a press, and the time of assuming a predetermined forming posture at what level of the rotation. The rotary cam  5  is rotated at a sloped portion  62   a  of the cam face  62 , and the forming posture is maintained at a perpendicular portion  62   b  of the cam face  62 .  
       [0024] The driver  53  is fixed with a bolt  63  to the upper die  3 .  
       [0025] The cylinder  51  causes the rotary cam  5  to return when the upper die  3  rises, and the cam follower  55  is positioned not to be in contact with the cam face  62  of the driver  53 .  
       [0026]FIG. 18 shows a state where the upper die  3  is at a top dead center, and FIG. 19 shows a state where the upper die  3  is at a bottom dead center.  
       [0027] When the upper die  3  descends from the state of the top dead center, the sloped portion  62   a  of the cam face  62  of the driver  53  of the upper die  3  engages the cam follower  55  of the cam follower arm  52  of the lower die  1 . Then, when the rotary cam  5  rotates, and the cam follower  55  reaches the perpendicular portion  62   b  of the cam face  62 , the rotary cam  5  holds the forming posture. When the intrusive forming process has been completed, the upper die  3  rises. Since nothing remains to constrain the cam follower arm  52 , the rotary cam  5  is returned by the cylinder  51  to the original position.  
       [0028]FIG. 20 is a plan view of the configuration shown in FIG. 19.  
       [0029] The rotating apparatus for rotating the rotary body according to the extension and retraction of the piston rod of the cylinder is configured such that the supporting axes are provided to protrude from two ends of the rotary body, the supporting axes are held to rotatably provide the rotary body, the central portion of the cam follower arm is fixed to the supporting axes, the threaded rod portion that is provided at the end of the piston rod and that connects the one end of the cam follower arm and the piston rod is inserted into the connecting member, the nut threaded on the threaded rod portion is tightened, and the connecting member and the end of the piston rod is thereby connected.  
       [0030] However, the rotation start position and the rotation termination position of the cam follower arm are not determined because of variations in the amount of tightening the nut. As such, the rotary cam cannot be accurately positioned. When intrusive forming is performed in the above-described state, cases can occur in which high-quality work processing cannot be implemented.  
       SUMMARY OF THE INVENTION  
       [0031] In view of the above circumstances, the present invention is to provide a rotary drive apparatus for a rotary body for rotating the rotary body through extension and extraction of the piston rod of the cylinder, wherein a rotation start and a rotation termination position can be accurately determined, intrusive forming can be performed with the rotary cam being accurately positioned, and high-quality work processing can be implemented. The rotary drive apparatus is configured such that supporting axes are provided to individually protrude from two ends of the rotary body, the supporting axes are held and the rotary body are rotatably provided, a central portion of a cam follower arm is fixed to the supporting axis, one end of the cam follower arm and the piston rod of the cylinder are connected via a guide plate provided therebetween, a guide groove is carved on the guide plate to rotate the cam follower separately in a stroke direction of the piston rod and in a direction perpendicular thereto, and a cam follower at the end of the cam follower arm is engaged with the guide groove.  
       [0032] More specifically, the present invention provides a rotary-cam driven apparatus for a negative-angle forming die comprising a lower die for mounting a work of a thin metallic sheet onto a supporting portion, an upper die that is linearly descended to the lower die for forming the work by hitting against the work, a rotary cam rotatably provided in the lower die to comprise an intrusive-forming portion that is formed at an edge portion closer to a supporting portion and that is intruded from a locus of the upper die, a slide cam that comprises an intrusive-forming portion and that is provided to the upper die to be slidable in opposition to the rotary cam, and an automatic returning tool provided to the lower die for rotationally retracting the rotary cam to be in a state where the work can be taken out from the lower die upon completion of the forming process, wherein the slide cam performs the forming process of the work set on the supporting portion of the lower die by using the intrusive forming portion of the rotary cam, and the rotary cam is rotationally retracted by the automatic returning tool to enable the formed work to be taken out from the lower die; wherein the rotary-cam driven apparatus is configured such that supporting axes are provided to individually protrude from two ends of the rotary body, the supporting axes are held by the lower die and the rotary body are rotatably provided, a central portion of a cam follower arm is fixed to the supporting axis, one end of the cam follower arm and the piston rod of the cylinder are connected via a guide plate provided therebetween, a guide groove is carved on the guide plate to rotate the cam follower separately in a stroke direction of the piston rod and in a direction perpendicular thereto, and a cam follower at the end of the cam follower arm is engaged with the guide groove. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0033]FIG. 1 is a side view of a state where an upper die of a rotary-cam driven apparatus for a negative-angle forming die according to a practical embodiment of the present invention is positioned at a top dead center;  
     [0034]FIG. 2 is a side view of state where the upper die shown in FIG. 1 is positioned at a bottom dead center;  
     [0035]FIG. 3 is a plan view of a state excluding the upper die shown in FIG. 2;  
     [0036]FIG. 4 is a front view of a fixing plate according to the present invention;  
     [0037]FIG. 5 is a side view of the fixing plate according to the present invention;  
     [0038]FIG. 6 is a front view of a guide plate according to the present invention;  
     [0039]FIG. 7 is a side view of the guide plate according to the present invention;  
     [0040]FIG. 8 is a front view of a guide plate support according to the present invention;  
     [0041]FIG. 9 is a side view of the guide-plate support according to the present invention;  
     [0042]FIG. 10 is a plan view of the guide plate support according to the present invention;  
     [0043]FIG. 11 is a vertical cross-sectional view of a state where an upper die of a conventional negative-angle forming die for performing intrusive forming is positioned at a top dead center;  
     [0044]FIG. 12 is a vertical cross-sectional view of a state where, in the conventional negative-angle forming die, a rotary cam is operated by an air cylinder to assume a forming posture, the upper die descends, and a work is pressed by a pad;  
     [0045]FIG. 13 is a vertical cross-sectional view of a state where the upper die has descended, abutted on a lower die, and begun to contact the work in the conventional negative-angle forming die;  
     [0046]FIG. 14 is a vertical cross-sectional view of a state where the upper die of the conventional negative-angle forming die is positioned at a bottom dead center;  
     [0047]FIG. 15 is a vertical cross-sectional view of a state where the intrusive forming was completed and has begun to rise in the conventional negative-angle forming die;  
     [0048]FIG. 16 is a vertical cross-sectional view where the conventional negative-angle forming die performed the intrusive forming, and the upper die further rose, and is positioned at the top dead center;  
     [0049]FIG. 17 is a schematic view showing a pattern diagrams of a rotary-cam driven apparatus for a negative-angle forming die;  
     [0050]FIG. 18 is a side view showing a state where an upper die of the practical example of the rotary-cam driven apparatus for the negative-angle forming die is positioned at a top dead center;  
     [0051]FIG. 19 is a side view of a state where the upper die shown in FIG. 18 is positioned at a bottom dead center; and  
     [0052]FIG. 20 is a plan view of the state shown in FIG. 19. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0053] Hereinbelow, the present invention will be described in detail using an a practical embodiment thereof with reference to the accompanying drawings.  
     [0054] The embodiment of the present invention is shown in FIGS.  1  to  10 , in which the same numerals or symbols will be used to refer to the same components shown in FIGS.  17  to  20 .  
     [0055] A guide plate  71  is provided between a piston rod  69  of the cylinder  51  and a cam follower arm  70 . A cam follower  73  of cam follower arm  70  is fitted into a guide groove  72  of the guide plate  71 .  
     [0056] The cam follower arm  70  is provided to extend rectangular from a disc portion in the center. The cam follower arm  70  is formed of two members, in which a cam follower  55  is rotatably provided to one end thereof, and the cam follower  73  is fitted into the guide groove  72  of the other end thereof.  
     [0057] The guide groove  72  provided onto the guide plate  71 . The guide groove  72  is carved in regions in the direction of the stroke of the piston rod  69  and the direction perpendicular thereto to allow the cam follower  73  to rotate. The guide groove  72  is thus carved to cover separate regions in the direction of the stroke of the piston rod  69  and the direction perpendicular thereto (in the drawings, the guide groove  72  is carved in upper and lower regions) in order to allow the cam follower  73  as well as the rotary cam  5  to rotate. The guide groove  72  is carved to allow the cam follower  73  to smoothly and is set slightly longer than the stroke of the piston rod  69 . The guide groove  72  includes an horizontal groove  72   a  and a sloped groove  72   b.    
     [0058] The piston rod  69  of the cylinder  51  and the guide plate  71  are connected by turning a threaded end portion of the piston rod  69  into the guide plate  71 , and a fixing plate  74  shown in FIGS. 4 and 5 is used to lock rotation of the piston rod  69 . As shown in FIGS. 2 and 4, two plane portions  76   a  formed by cutting two sides are provided between a small-diameter end portion  69   a  and a large-diameter base end portion  69   b  of the piston rod  69 . In addition, a groove  76  of the fixing plate  74  is externally fitted to the two plane portions  76   a , and the fixing plate  74  is fixed with a bolt  78  to the fixing plate  74 .  
     [0059] As shown in FIGS. 6 and 7, the guide groove  72  is on the reverse side of a portion shown in FIGS. 1 and 2, and the cam follower  73  of the cam follower arm  70  is engaged therewith. On the obverse side, horizontal guide grooves  75  and  76  are carved to horizontally transfer the extension and extraction of the piston rod  69  of the cylinder  51 . In addition, a roller  78  and rollers  79  and  80  of a guide-plate support  77  shown in FIGS.  8  to  10  are engaged with the horizontal guide groove  75  and horizontal guide groove  76 , respectively. The guide-plate support  77  is fixed with a bolt  81  to the lower die  1 .  
     [0060]FIG. 1 shows a state where the upper die  3  is positioned at a top dead center, and FIG. 2 shows a state where the upper die  3  is positioned at a bottom dead center. FIG. 3 is a plan view showing a state excluding the upper die  3  shown in FIG. 2.  
     [0061] When the upper die  3  descends from the state of the top dead center, the sloped portion  62   a  of the cam face  62  of the driver  53  of the upper die  3  abuts against the cam follower  55  of the cam follower arm  70  of the lower die  1 . Then, when the rotary cam  5  rotates, and the cam follower  55  reaches the perpendicular portion  62   b  of the cam face  62 , the rotary cam maintains the forming posture. When an intrusive forming process for a work has been completed, the upper die  3  rises. In this case, nothing remains to constrain the cam follower arm  70 , the rotary cam  5  is returned by the cylinder  51  to the original position.  
     [0062] In the state of the top dead center shown in FIG. 1, the cam follower  73  of the cam follower arm  70  in the guide groove  72  of the guide plate  71  is positioned in the sloped groove  72   b . As the upper die  3  descends, the cam follower  73  moves from the sloped groove  72   b  to a linear groove  72   a . When the cam follower  73  is positioned in the linear groove  72   a , the cam follower  55  is positioned at the perpendicular portion  62   b  of the driver  53  to cause the rotary cam  5  to assume the forming posture.  
     [0063] Conventionally, when the piston rod of the cylinder is connected by tightening the threaded portion, because of variations in the amount of tightening the threaded portion, a rotation start position and a rotation termination position of the rotary cam has not been able to be precisely determined. As such, when intrusive forming is performed in the above-described state, high-quality work processes have not been able to be implemented. However, the present invention is arranged such that operation in the piston stroke of the cylinder  51  is performed through the engagement between the cam follower  73  and the guide groove  72 , no influences are caused on the rotation start and the rotation termination of the rotary cam, and high-quality work processing can therefore be implemented.  
     [0064] As described above, according to the present invention, the rotary drive apparatus for a rotary body for rotating the rotary body through extension and extraction of a piston rod of a cylinder is arranged such that supporting axes are provided to individually protrude from two ends of the rotary body, the supporting axes are held and the rotary body are rotatably provided, a central portion of a cam follower arm is fixed to the supporting axis, one end of the cam follower arm and the piston rod of the cylinder are connected via a guide plate provided therebetween, a guide groove is carved on the guide plate to rotate the cam follower separately in a stroke direction of the piston rod and in a direction perpendicular thereto, and a cam follower at the end of the cam follower arm is engaged with the guide groove. As such, in the rotary drive apparatus for a rotary body for rotating the rotary body through extension and extraction of the piston rod of the cylinder, and a rotation start and a rotation termination position can be accurately determined, intrusive forming can be performed with the rotary cam being accurately positioned, thereby enabling high-quality work processing to be implemented. Conventionally, when the cylinder is directly connected to the rotary body, the power of the cylinder is abruptly transferred with shocks. However, according to the present invention, since the cylinder and the rotary body are connected via the guide groove, shocks in abrupt movements of the cylinder and the piston rod are absorbed by the guide groove. As such, no shocks are transferred to the rotary body.  
     [0065] More specifically, the present invention is a rotary-cam driven apparatus for a negative-angle forming die comprising a lower die for mounting a work of a thin metallic sheet onto a supporting portion, an upper die that is linearly descended to the lower die for forming the work by hitting against the work, a rotary cam rotatably provided in the lower die to comprise an intrusive-forming portion that is formed at an edge portion closer to a supporting portion and that is intruded from a locus of the upper die, a slide cam that comprises an intrusive-forming portion and that is provided to the upper die to be slidable in opposition to the rotary cam, and an automatic returning tool provided to the lower die for rotationally retracting the rotary cam to be in a state where the work can be taken out from the lower die upon completion of the forming process, wherein the slide cam performs the forming process of the work set on the supporting portion of the lower die by using the intrusive forming portion of the rotary cam, and the rotary cam is rotationally retracted by the automatic returning tool to enable the formed work to be taken out from the lower die; wherein the rotary-cam driven apparatus is configured such that supporting axes are provided to individually protrude from two ends of the rotary body, the supporting axes are held by the lower die and the rotary body are rotatably provided, a central portion of a cam follower arm is fixed to the supporting axis, one end of the cam follower arm and the piston rod of the cylinder are connected via a guide plate provided therebetween, a guide groove is carved on the guide plate to rotate the cam follower separately in a stroke direction of the piston rod and in a direction perpendicular thereto, and a cam follower at the end of the cam follower arm is engaged with the guide groove. Conventionally, when the cylinder is directly connected to the rotary body, the power of the cylinder is abruptly transferred with shocks. However, according to the present invention, since the cylinder and the rotary body are connected via the guide groove, shocks in abrupt movements of the cylinder and the piston rod are absorbed by the guide groove. As such, no shocks are transferred to the rotary body.