Abstract:
A spring manufacturing apparatus with a reduced number of driving sources, yet capable of adjusting the relative positions among the bending dices with higher precision when manufacturing a spring is to be provided. A second bending dice mounting slider and a third bending dice mounting slider are symmetrically located about a center line extended from a moving direction of a first bending dice mounting slider. An arm mechanically connects the first bending dice mounting slider and the second bending dice mounting slider, or the first bending dice mounting slider and the third bending dice mounting slider, so that either of a driving source that drives the second bending dice mounting slider or a driving source that drives the third-bending dice mounting slider moves the first bending dice mounting slider, thus to determine a winding direction of a wire for manufacturing a spring.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This Nonprovisional application claims priority under 35 U.S.C.§119(a) on Patent Application No. 2005-181017 filed in Japan on Jun. 21, 2005, the entire contents of which are hereby incorporated by reference. 
   BACKGROUND OF THE INVENTION 
   The present invention relates to a spring manufacturing apparatus with a reduced number of driving sources, yet capable of precisely bending the spring. 
   A conventional spring manufacturing apparatus has a wire processing space where the wire is formed into a spring, defined by a front wall of a casing. The spring manufacturing apparatus includes at least a pair of wire feeding rollers that delivers the wire to the wire processing space, via a wire path. The wire fed into the wire processing space is bent by a bending dice mounted on three bending dice mounting sliders, installed so as to move into and out of the wire processing space. 
   The three bending dice mounting sliders are located on the wire path at a position opposing the outlet of the wire, and symmetrically with respect to a center line extended from the wire path. The three bending dice mounting sliders are respectively provided with a motor serving as a driving source. Controlling the rotation of the motor so as to locate the bending dice mounting sliders at a desired relative position enables forming the spring in a desired shape. 
   The spring manufacturing apparatus thus structured, however, requires a motor for each of the three bending dice mounting sliders for the positioning. Accordingly, it is difficult to reduce the manufacturing cost, and hence the running cost remains high. From such viewpoint, a spring manufacturing apparatus with a single driving source that drives the bending dice mounting sliders has been developed. In such spring manufacturing apparatus, the driving source directly drives a first bending dice mounting slider. The remaining bending dice mounting sliders are mechanically linked with the first bending dice mounting slider and provided with a removable arm, so that the bending dice mounting sliders necessary for manufacturing the spring can be driven. 
   BRIEF SUMMARY OF THE INVENTION 
   In the spring manufacturing apparatus including a single driving source that drives the bending dice mounting sliders, the first bending dice mounting slider directly driven by the driving source can be linearly moved with a ball screw directly attached to the rotating shaft of the driving source. The other bending dice mounting sliders are mechanically linked with the first bending dice mounting slider via the arm, which swings according to the linear motion of the first bending dice mounting slider. The center of the swinging motion of the arm is located at a middle point between the first bending dice mounting slider and the other bending dice mounting sliders linked thereto, and hence the other bending dice mounting sliders can only move along an arc created by the swinging motion of the arm. Accordingly, the other bending dice mounting sliders cannot be moved at the same speed as the first bending dice mounting slider, and therefore it is difficult to improve manufacturing precision over a certain level when manufacturing a spring with a variable outer diameter. 
   The present invention has been conceived in view of the foregoing situation, with an object to provide a spring manufacturing apparatus in which the first bending dice mounting slider is linked with the other bending dice mounting sliders thus to reduce the number of driving sources, and which is capable of adjusting the relative positions among the bending dices with higher precision, when manufacturing a spring. 
   Another object of the present invention is to provide a spring manufacturing apparatus including an arm that swings over a rotation radius longer than a spacing among the linked bending dice mounting sliders, so as to create more accurate approximation line of the movement of the bending dice mounting sliders caused by the swinging motion of the arm. 
   Still another object of the present invention is to provide a spring manufacturing apparatus including a groove cam mechanism, so that the moving direction of the bending dice, caused by the movement of the bending dice mounting slider, can be linearly approximated upward or downward by a predetermined angle. 
   To achieve the foregoing objects, a first aspect of the present invention provides a spring manufacturing apparatus comprising a wire path through which a wire passes to enter a wire processing space for forming the wire into a spring by using a bending dice; at least a pair of wire feeding rollers that pressingly holds the wire and feeds the wire to the wire processing space; and a first, a second and a third bending dice mounting slider disposed so as to move into and out of the wire processing space; in which the first bending dice mounting slider is located at a position opposing an outlet of the wire path, and the second and the third bending dice mounting sliders are symmetrically located with respect to a center line along the moving direction of the first bending dice mounting slider; further comprising an arm that mechanically connects the first and the second bending dice mounting slider, or the first and the third bending dice mounting slider selectively; a first driving source that drives the second bending dice mounting slider; and a second driving source that drives the third bending dice mounting slider; wherein one of the first and the second driving source, selected according to which bending dice mounting sliders are connected by the arm, causes the first bending dice mounting slider to move in an interlocked manner so as to determine a winding direction of the wire for manufacturing a spring. 
   A second aspect of the present invention provides a spring manufacturing apparatus according to the first aspect, wherein the arm has a center of a swinging motion thereof on an extension of a line connecting the mechanically connected portion between the first and the second bending dice mounting slider, or between the first and the third bending dice mounting slider. 
   A third aspect of the present invention provides a spring manufacturing apparatus according to the first and the second aspect, in which the first bending dice mounting slider comprises a swinging member with a bending dice attached to an end portion, disposed so as to swing about the other end portion located close to a generally central portion of the first bending dice mounting slider; a block with a cam groove formed above and below the first bending dice mounting slider; and a cam mechanism including a slider that fits in the cam groove; wherein one of the block and the slider is connected to the swinging member. 
   According to the first aspect, the first bending dice mounting slider is located at a position opposing the wire outlet of the wire path, and the second and the third bending dice mounting slider are symmetrically located with respect to a center line along the moving direction of the first bending dice mounting slider. The first and the second bending dice mounting slider, or the first and the third bending dice mounting slider are selectively connected by the removable arm. When the first and the second bending dice mounting slider are connected by the arm, the driving source that drives the second bending dice mounting slider is activated to cause the first bending dice mounting slider to move in an interlocked manner, to thereby determine the winding direction of the wire for manufacturing the spring. When the first and the third bending dice mounting slider are connected by the arm, the driving source that drives the third bending dice mounting slider is activated to cause the first bending dice mounting slider to move in an interlocked manner, to thereby wind the wire in the opposite direction for manufacturing the spring. 
   Such configuration requires only two driving sources that drive the bending dice mounting sliders, thus allowing reducing power consumption compared to the apparatus with three driving sources. Also, selectively switching the bending dice mounting slider to be connected by the arm determines the winding direction of the wire. 
   Further, in the spring manufacturing apparatus with a single driving source, the second bending dice mounting slider has to be moved in an interlocked manner at a constant speed, for example when manufacturing a spring with a progressively increasing outer diameter. However, it is difficult to cause the bending dice mounting slider not directly driven by the driving source to move at a constant speed. In contrast, according to the first aspect the first bending dice mounting slider is directly driven by one of the driving sources, and the other bending dice mounting sliders are indirectly driven by the other driving source. Therefore, numerically controlling the rotation of the driving sources permits moving the both bending dice mounting sliders at a constant speed, thus enabling manufacturing the spring with higher precision, even when the spring has a progressively increasing outer diameter. 
   According to the second aspect, the arm has the center of the swinging motion thereof on an extension of the line connecting the mechanically connected portion between the first and the second bending dice mounting slider, or between the first and the third bending dice mounting slider. Such structure provides a larger rotation radius to the arm, to thereby make the swinging motion of the arm, caused by for instance the third bending dice mounting slider, closer to a linear motion. The second aspect, therefore, allows the first bending dice mounting slider to linearly move at a constant speed with higher precision, resulting in more precise manufacturing of springs in various shapes. 
   According to the third aspect, the first bending dice mounting slider is provided with a swinging member with a bending dice attached to an end portion, disposed so as to swing about the other end portion located close to a generally central portion of the first bending dice mounting slider. The first bending dice mounting slider is also provided with a block with a cam groove formed above and below the first bending dice mounting slider, and a cam mechanism including a slider that fits in the cam groove, such that one of the block and the slider is connected to the swinging member. Such structure permits causing the bending dice to linearly move upward or downward by a predetermined angle, interlocked with the first bending dice mounting slider which is not provided with the driving source, by the swinging motion of the swinging member. 
   The first aspect requires only two driving sources that drive the bending dice mounting sliders, thus allowing reducing power consumption compared to the apparatus with three driving sources. Also, selectively switching the bending dice mounting slider to be connected by the arm determines the winding direction of the wire. 
   Further, in the spring manufacturing apparatus with a single driving source, the second bending dice mounting slider has to be moved in an interlocked manner at a constant speed, for example when manufacturing a spring with a progressively increasing outer diameter. However, it is difficult to cause the bending dice mounting slider not directly driven by the driving source to move at a constant speed. In contrast, according to the first aspect the first bending dice mounting slider is directly driven by one of the driving sources, and the other bending dice mounting sliders are indirectly driven by the other driving source. Therefore, numerically controlling the rotation of the driving sources permits moving the both bending dice mounting sliders at a constant speed, thus enabling manufacturing the spring with higher precision, even when the spring has a progressively increasing outer diameter. 
   The structure according to the second aspect provides a larger rotation radius to the arm, to thereby make the swinging motion of the arm, caused by for instance the third bending dice mounting slider, closer to a linear motion. The second aspect, therefore, allows the first bending dice mounting slider to linearly move at a constant speed with higher precision, resulting in more precise manufacturing of springs in various shapes. 
   The structure according to the third aspect permits causing the bending dice to linearly move upward or downward by a predetermined angle, together with the first bending dice mounting slider which is not provided with the driving source, by the swinging motion of the swinging member, resulting in more precise manufacturing of springs in various shapes. 
   The above and further objects and features of the invention will more fully be apparent from the following detailed description with accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       FIG. 1  is a front view showing a main portion of a spring manufacturing apparatus according to an embodiment of the present invention; 
       FIG. 2  is a cross-sectional view taken along the line II-II of  FIG. 1 , showing a structure of a first bending dice mounting slider; 
       FIG. 3  is a fragmentary cross-sectional view showing a structure of a cam mechanism; 
       FIG. 4A  is a plan view showing an arm; 
       FIG. 4B  is a cross-sectional view taken along the line IV-IV of the arm; 
       FIG. 5  is a cross-sectional view taken along the line V-V of  FIG. 1 , showing a structure of a second (third) bending dice mounting slider; and 
       FIG. 6  is a graphic diagram showing moving directions of the first and the second bending dice mounting slider. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Hereunder, the present invention will be described based on the drawings showing an embodiment thereof.  FIG. 1  is a front view showing a main portion of a spring manufacturing apparatus according to an embodiment of the present invention. 
   As shown in  FIG. 1 , in the spring manufacturing apparatus according to the embodiment, a wire  1  is led to two pairs of wire feeding rollers  7 ,  7 , . . . each including an upper and a lower roller. In the wire feeding rollers  7 ,  7 , . . . , the upper rollers  7 ,  7  rotate counterclockwise, and the lower rollers  7 ,  7  rotate clockwise, thus to feed the wire  1  to the wire path  2 . 
   The wire  1  led to an end portion of the wire path  2  is introduced to a wire processing space  5 , to be butted to, for example, bending dices  13 ,  33  mounted on a tip portion of a first bending dice mounting slider  11  and a second bending dice mounting slider  32 , respectively. The wire  1  is bent and deformed in a desired direction according to an angle and relative positions of the bending dices  13 ,  33  to which the wire  1  is butted, to be wound in a desired spring shape. 
   A cutting tool slider  46 , with a cutter  48  fixed to an end portion thereof, is provided for cutting the wound spring in cooperation with a core bar  47  projecting from a front wall. The cutting tool slider  46  moves up and down into and out of the wire processing space  5  along a guardrail (not shown) so as to hold the wire  1  between the cutter  48  and the core bar  47 , and the cutter  48  descends until slidingly contacting the core bar  47 , thus to cut the wire  1 . 
   The first bending dice mounting slider  11  is located at a position opposing the outlet of the wire  1  of the wire path  2  across the wire processing space  5 .  FIG. 2  is a cross-sectional view taken along the line II-II of  FIG. 1 , showing a structure of the first bending dice mounting slider. 
   The first bending dice mounting slider  11  includes a guide rail  10  placed on the front wall  4  in a direction of an extension of the center line of the wire in the wire path  2 , so that the slider main body  12  can slide along the guide rail  10 , back and forth with respect to the wire processing space  5 . At the tip portion of the slider main body  12  the bending dice  13  is attached, for bending the wire  1  in the wire processing space  5 . 
   The slider main body  12  is not provided with a direct driving source. The slider main body  12  is driven interlocked with a movement of a second bending dice mounting slider  32  or a third bending dice mounting slider  52  to be described later, by an arm  37 , also to be described later, swingably attached to a generally vertical plane parallel to the front wall  4 . Accordingly, motors M 2 , M 3  serving as driving sources are connected to the second bending dice mounting slider  32  or the third bending dice mounting slider  52  respectively. 
   The slider main body  12  includes a groove  14  for a second projection  42  of the arm  37  to be fitted in. When the motor M 2  or M 3  serving as the driving source rotates to move the second bending dice mounting slider  32  or the third bending dice mounting slider  52 , the second projection  42  slides along the groove  14 , so that the first bending dice mounting slider  11  moves interlocked therewith. 
   Here, the slider main body  12  includes a swinging member  20  that can swing about an axle  19  perpendicularly oriented with respect to the front wall  4 . The winging member  20  is interlocked with a cam mechanism  21 , such that when the second bending dice mounting slider  11  horizontally moves away from the wire processing space  5  the slider main body  12  is caused to swing upward by the swinging member  20 , so that the bending dice  13  attached to the tip portion swings upward. 
     FIG. 3  is a fragmentary cross-sectional view showing a structure of the cam mechanism  21 . As shown in  FIG. 3 , the cam mechanism  21  is removably attached to the front wall  4 , and includes a block  22  with a cam groove  23 , a protruding piece  25  of the swinging member  20 , and a slider  27  pivotally fitted in the cam groove  23  by an axle  26 . The center line of the cam groove  23  is inclined counterclockwise by a predetermined acute angle α with respect to the moving direction of the first bending dice mounting slider  11 . The slider  27  is of a size that does not create a play when fitted in the cam groove  23 , and hence kept from rattling widthwise of the cam groove  23 . At the end portion of the swinging member  20 , the bending dice  13  is attached. 
     FIGS. 4A and 4B  depict a structure of the arm  37 , and  FIG. 4A  is a plan view of the same, while  FIG. 4B  is a cross-sectional view taken along the line IV-IV of the arm  37 . The arm  37  is removably mounted on a base  30  fixed at a predetermined position on the front wall  4 , so as to swing about the base  30  when mounted thereon. 
   The arm  37  includes the first projection  41  and the second projection  42 , at an end portion thereof opposite to the base  30  and at a middle point therebetween respectively. The first projection  41  fits in a groove  34 ,  54  of the second bending dice mounting slider  32  or the third bending dice mounting slider  52 , and the second projection  42  fits in the groove  14  of the first bending dice mounting slider  11 . 
     FIG. 1  represents a state that the first projection  41  of the arm  37  is engaged with the third bending dice mounting slider  52 , in which case the wire  1  is bent by the bending dices  13 ,  33  respectively attached to the first bending dice mounting slider  11  and the second bending dice mounting slider  32 , and the third bending dice mounting slider  52  is not directly involved in the manufacturing of the spring. However, the first bending dice mounting slider  11  is caused to move by the driving source that drives the third bending dice mounting slider  52 . 
     FIG. 5  is a cross-sectional view taken along the line V-V of  FIG. 1 , showing a structure of the second (third) bending dice mounting slider  32  ( 52 ). The second (third) bending dice mounting slider  32  ( 52 ) includes a guide rail  30  ( 50 ) inclined in a predetermined angle β with respect to an extension of the center line of the wire  1  in a wire guide  3 , so that the second (third) bending dice mounting slider  32  ( 52 ) can slide back and forth along the guide rail  30  ( 50 )with respect to the wire processing space  5 . In  FIG. 1 , the bending dice  33  is attached to the tip portion of the second (third) bending dice mounting slider  32  ( 52 ), but the bending dice  53  is not attached to the tip portion of the second (third) bending dice mounting slider  32  ( 52 ). Here, the second bending dice mounting slider  32  and the third bending dice mounting slider  52  are symmetrically located about a symmetry axis extended from the center line of the wire  1  in the wire path  2 , at positions inclined by the predetermined angle β. 
   The second (third) bending dice mounting slider  32  ( 52 ) is provided with the motor M 2  (M 3 ) serving as the driving source that directly drives the second (third) bending dice mounting slider  32  ( 52 ). The first projection  41  at the end portion of the arm  37  is fitted in the groove  34  ( 54 ) of the second (third) bending dice mounting slider  32  ( 52 ), via an axle  39  ( 59 ). The axle  39  ( 59 ) slides along the groove  34  ( 54 ). This causes the second (third) bending dice mounting slider  32  ( 52 ) to slide in the predetermined angle β, so that the arm  37  swings thus to move the first bending dice mounting slider  11  in a predetermined direction, in an interlocked manner. 
   The motor M 2  (M 3 ) can rotate both in forward and reverse directions. A ball screw  35  ( 55 ) is attached to the rotating shaft of such motor M 2  (M 3 ) so as to convert the rotation of the shaft into linear motion along the center of axis, and a female-threaded piece  36  ( 56 ) that thread-fits with the ball screw  35  ( 55 ) is attached to the second (third) bending dice mounting slider  32  ( 52 ). Accordingly, the rotation of the motor M 2  (M 3 ) in the forward or reverse direction causes the ball screw  35  ( 55 ) to rotate, thus to move the second (third) bending dice mounting slider  32  ( 52 ) back and forth with respect to the wire processing space  5 . 
   The spring manufacturing apparatus thus configured is operated as follows. The description given below refers to a case where the bending dices  13 ,  33  are respectively attached to the first bending dice mounting slider  11  and the second bending dice mounting slider  32 , and the arm  37  connects the first bending dice mounting slider  11  and the third bending dice mounting slider  52  for manufacturing a spring with a progressively increasing outer diameter. 
   Before the wire  1  is supplied, the first bending dice mounting slider  11  and the second bending dice mounting slider  32  are located at an end portion on the left. When the wire  1  starts to be supplied, the motors M 2 , M 3  receive a rotation instruction signal so as to rotate at a predetermined rotation speed. The rotation of the motor M 2  causes the second bending dice mounting slider  32  to move upward to the left at the predetermined angle β. The rotation of the motor M 3  causes the third bending dice mounting slider  52  to move downward to the right at the predetermined angle β, so that the arm  37  causes the first bending dice mounting slider  11  to move away from the wire processing space  5  and the bending dice  13  moves upward to the right along a line inclined by a predetermined angle γ. 
     FIG. 6  is a graphic diagram showing moving directions of the first bending dice mounting slider  11  and the second bending dice mounting slider  32 . The bending dices  13 ,  33  include a groove at a central portion thereof, for accurately bending the wire  1 , and the central point P 1  of the groove of the bending dice  33  moves along a line L 1  shown in  FIG. 6 , and the central point P 2  of the groove of the bending dice  13  moves along a line L 2  in  FIG. 6 . 
   When the central point P 1  moves for example to a position B, the central point P 2  moves to a position b. Thus, the length, mounting position and shape of the arm  37 , as well as the rotation speed of the motors M 2 , M 3  are determined such that the both points linearly move interlocked with each other at a constant speed, maintaining a constant ratio between the travel distance of the central point P 1  on the line L 1  and that of the central point P 2  on the line L 2 . 
   It is to be noted that in  FIG. 6  a point A represents a lower end of the outlet of the wire  1  from the wire guide  3 . A line L 3  is a horizontal line, and a line L 4  is a vertical line. The position of the bending dice  33  is determined according to an outer diameter of a coil portion of the spring to be wound, and at the same time the position of the bending dice  13  is also determined. 
   Moving thus the bending dices  13 ,  33  in an interlocked manner from the point A enables manufacturing a spring with a right-wound coil portion with a progressively increasing outer diameter. For manufacturing a spring with a left-wound coil, the arm  37  is removed, to then connect the first bending dice mounting slider  11  and the third bending dice mounting slider  52 . The bending dice is replaced to the third bending dice mounting slider  52  from the second bending dice mounting slider  32 , and the first bending dice mounting slider  11  and the third bending dice mounting slider  52  are moved interlocked with each other thus to manufacture a spring with a left-wound coil. 
   It should be noted that the direction of the center line of the cam groove  23  does not imperatively have to be linearly oriented in the direction rotated counterclockwise by the predetermined acute angle α from the moving direction of the first bending dice mounting slider  11 . More broadly, forming the cam groove  23  in an arcuate shape with an appropriate rotation radius such that the bending dice  13  attached to the end portion of the swinging member  20  moves along a generally linear orbit allows moving the bending dice  13  along a line inclined upward by the predetermined angle α, according to a motion of the slider  27 . 
   As this invention may be embodied in several forms without departing from the spirit of essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds thereof are therefore intended to be embraced by the claims.