Abstract:
An apparatus for fastening contact pieces from a band of series connected contact pieces to leads basically includes a base frame having guiding and transporting elements for the contact pieces as well as crimping anvils and a plunger on which a crimper is arranged and which activates the transporting elements. The transporting elements include a finger which moves perpendicular to a transporting forward direction for engaging the contact pieces and then moves in the forward transporting direction. The finger, in cross sectional shape and size, fits into an opening in the contact pieces such that it is immediately near edges defining the opening in the transporting forward and opposite directions. In addition, a holding element drive preventer engages the contact pieces. Leads are centered relative to crimping claws of the contact pieces by two jaws in the form of simple levers mounted on the base frame and are spring biased to spread from one another but are urged together by downward movement of the plunger.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to processes and apparatus for crimping contact pieces to electrical leads and is more particularly concerned with such apparatus and processes in which leads are inserted between U formed, upwardly-extending, crimping claws of such contact pieces on a base frame while a rammer, with crimpers thereon, interact with the base frame to bend the crimping claws tightly about the leads. The invention concerns such apparatus and processes in which individual contact pieces are connected in series to form a band which is arranged and transported along the base frame in a forward transporting direction with a finger which engages the band and with a holding element which holds the band to prevent rearward, or motion opposite to the forward transport direction, transport thereof. 
     In well known processes the moving of electrical leads between upwardly extending crimping claws of contact pieces is difficult because arrangements of the leads to the upwardly extending crimping claws of the contact pieces is not sufficiently exact. The contact pieces, with their U-formed upwardly extending crimping claws, are shoved onto ends of leads without the lead ends being exactly positioned relative to the crimping claws. Because of this, individual strands of stranded wire forming lead ends sometimes strike the contact pieces when they are shoved therein so that they are not gripped by the crimping claws when they are bent. It is therefore a purpose of this invention to improve this prior art process such that lead ends, which are to be crimped to contact pieces, are more exactly arranged relative to the upwardly extending crimping claws and, in addition, are not moved between the claws, end first. 
     Also, by well known apparatus of the art of this invention a band of series connected contact pieces is transported in the forward direction by a lever-like finger whose angled free end is pressed by means of a spring on the band of series connected contact pieces. When the finger is transported in the forward direction, the angled, or bent, free end engages an edge of the contact pieces and shoves these in the forward transporting direction toward a crimping, or striking, stamp. Because the connection between the transporting finger and the contact pieces is only keyed to one side, and because the shoving of the finger is accomplished with great acceleration, a brake must be provided to prevent the contact pieces from being thrown beyond a desired position. This brake is often a plate pressed against the contact pieces by spring force from above. Because of the large acceleration force, a pressing force of the braking plate must be great and with pressure susceptible contact pieces there is often the danger that this force will deform the contact pieces. The pressing force of the braking plate must also be great because when the finger travels rearwardly, its backside is pulled, and lifted across, the contact pieces in order to grip the next contact piece. This opposite driving against an edge to lift the finger is accomplished at a high velocity which introduces a rearward shoving force which must be braked. Therefore, it is an object of this invention to provide a transporting arrangement that catches the momentum of contact pieces at the end of a transporting stroke and in which the transporting, or shoving finger, when traveling rearwardly, produces no rearward shoving force on the contact pieces. 
     SUMMARY 
     According to principles of this invention, an end portion of a lead is brought above the crimping claws in a lying position by the apparatus, is centered by two closing jaws and driven downwardly by a plunger between both arms of the crimping claws and is crimped herein by a crimping stamp. 
     The transport apparatus includes a finger which moves in a direction perpendicular to a forward transporting direction to move into an opening of a contact piece and out of the opening of the contact piece before it respectively moves in the transporting direction and in a direction opposite to the transporting direction, the finger having a shape and size, in cross section, such that it fits into the opening of the contact piece to be immediately next to, or in contact with, portions of the edge of the opening in the contact piece in the edge portion lying in both the transporting direction and the direction opposite the transporting direction. With this arrangement, the braking requirements of a holding element are reduced such that a hanging contact piece band is not pulled out of the apparatus by its own weight on an input side of the apparatus. 
     In one arrangement of the invention the holding element is a second finger which also moves perpendicular to the transporting direction opposite to movement of the first finger to grip the contact pieces but which does not move in the transporting or opposite directions. With this arrangement, a braking pressing force on the contact pieces is avoided. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings in which reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating principles of the invention in a clear manner. 
     FIG. 1 is a side view of an apparatus of this invention with a partial cross section taken through the middle of a plunger thereof; 
     FIG. 2 is a top view of the apparatus of FIG. 1, partially cutaway; 
     FIG. 3 is a side view of the apparatus of FIG. 1, taken from the other side, with the apparatus being partially cutaway in length along a vertical middle plane through a lateral piston rod; 
     FIG. 4 is a cross section taken on line A--A in FIG. 1; 
     FIG. 5 is a cross section taken on line B--B in FIG. 1; 
     FIG. 6 is a front view of the apparatus of FIG. 1 showing an upwardly driven plunger with parts being removed therefrom for clarity: 
     FIG. 7 is a front view of the apparatus of FIG. 1 with the plunger thereof being driven downwardly; 
     FIG. 8 is a partial cross section of the plunger taken on line C--C in FIG. 1; 
     FIG. 9 is a segmented top view of a band of series connected contact pieces with which the apparatus of this invention is used; 
     FIG. 10 is an alternate embodiment of a valve control to the right of the dividing line D of FIG. 2; and 
     FIG. 11 is an alternate embodiment of the finger-formed holding element shown to the right of the dividing line E in FIG. 1. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A base frame 1 of the apparatus of this invention is mounted on a press table with a supporting plug 3 of its plunger 2 suspended from a rammer 26. A guide plate 5, mounted on a floor plate 4 of the base frame 1 has guiding ledges 6 affixed thereon between which a band of series connected contact pieces 18 to be attached to lead ends are shoved forwardly, step wise, toward an insulation crimper 7 and a wire crimper 8 as well as toward a separating knife 9. The forward shoving is accomplished through a first finger 10 which is pneumatically driven downwardly through an opening 19 of a to-be-attached contact piece 18, is then driven forwardly in a transporting direction toward the crimpers 7 and 8, is raised, and finally is driven back in a direction opposite the forward transporting direction. While the first finger 10 is being driven upwardly, a second, laterally-nonmovable finger, 11 is driven pneumatically downwardly to engage another contact piece 18 and thereby hold the band of series connected contact pieces in its position. When the first finger 10 is driven into the next contact piece 18 the second finger 11 releases its contact piece 18 and is driven again upwardly. Thus, the first and second contact-piece-engaging fingers 10 and 11 are driven axially opposite to one another. 
     The axial driving of the first and second fingers 10 and 11 is accomplished with respective cylinders 12 and 13 which are energized pneumatically by air pressure. The air pressure connections in the appropriate cylinders 12 and 13 are represented in FIG. 1 by reference numerals 14, 15, 16, and 17. These connections are interconnected via a cross connection such that connection 14 is interconnected with connection 16 and connection 15 is interconnected with connection 17. 
     The shoving, or transporting, of contact pieces 18 in the forward direction toward the crimpers 7 and 8 is accomplished by means of the first finger 10. In this regard, the cylinder 12 is laterally driven by a piston rod 20. The cylinder 12 is attached to the piston rod 20 via an intermediate piece 79 and a pin 22. To ensure that the cylinder 12 does not rotate about the axis of the piston rod 20, the intermediate piece 79 is affixed to a shaft 21 which slidingly engages the base frame 1. 
     The plunger 2, which carries the crimpers 7 and 8 and the separating knife 9, rides in a track of the base frame 1. A coupling of the plunger with the rammer 26 is accomplished by the supporting plug 3. The supporting plug 3 is formed with two steps therealong so as to have a head portion, which is shoved in a T-formed slot 25 of the rammer 26, and a finger-like free end 27 which extends through a head plate 78 of the plunger 2. A compression spring 32 is mounted on the finger-like free end of the supporting plug 3 and prestressed thereon in a compressed condition by a spring ring clip 23. A screw 28 is mounted laterally in the plunger 2 with an eccentrically arranged pin 29 positioned under a second step of the supporting plug 3 such that turning the screw 28 can lift the supporting plug 3 against the spring 32. Thus, easy adjustment of the supporting plug 3 within the rammer 26 is possible. To change the lift position of the plunger 2, in order to change the deepest driven position of the crimpers 7 and 8 for example, a threaded bolt 30 is mounted in the plunger 2 from the top or head side which can be rotated by means of a worm 31 so that its height can be adjusted. Should, for example, the plunger 2 be driven deeper into the base frame 1 in order to drive the crimpers 7 and 8 deeper, the threaded bolt 30 is screwed out of the top of the plunger 2 and thereby produces a space between the plunger 2 and the rammer 26. The prestressed spring 32 mounted on the supporting plug has the purpose of maintaining the plunger 2 tightly against the rammer 26. This is particularly important because when adjusting the apparatus the rammer 26 is driven downwardly without a contact piece 18 in the apparatus. Without the compression spring 32 the crimpers 7 and 8 would come down hard on a crimper anvil 33 and could cause damage. 
     The axial drive of the first and second fingers 10 and 11 and the forward travel of the cylinder 12 in the axial direction of the piston rod 20 is carried out as follows: when the rammer 26 is driven downwardly a lateral pin 34 of an axially displaceable mounted pin 35 glides along on an angled surface 36 of a block 38 which is mounted on one side at axis 37 and engages the plunger 2 to thereby shove the axially displaceable pin in the direction X. This axially displaceable pin 35 activates with its head 39 a valve 40. If the plunger 2 is driven further downwardly, the lateral pin 34 glides along a vertical surface 41 and moves eventually against the force of the spring 51 backwardly into a trap 42. With upward movement, the lateral pin 34 glides across angled surface 43 and rotates the block 38 against the force of a spiral spring 44. 
     In a rest position, the first finger 10 finds itself in its deepest, or down, position immediately adjacent the second finger 11. Through activation of the valve 40, air pressure is provided to a 5/2-way, pneumatically controlled, slide valve 46. With this, air pressure is provided to the piston rod 20 which is thereby driven in the direction Z and the first finger 10, which is engaging a contact piece 18, is shoved forwardly in the direction of the crimping apparatus. At its end position, a control pin 48 strikes a slide 49 and therewith activates a control valve 45 through which air pressure is given to the cylinders 12 and 13 via air connections 14 and 16. Because of this, the second finger 11 is driven downwardly into an opening 19 of a contact piece 18 while the first finger 10 is pulled out of a contact piece 18 and is moved toward its upper position. By means of a throttle, or similar delaying agency, pressure is provided over a control line to the slide valve 46 which is thereby switched so that the piston rod 20 receives pressure over a channel 47 and is driven in the Y direction. At the end position of the cylinder 12 its control pin 48, switches the control valve 45. With this, air pressure is given to the air connectors 15 and 17 of the cylinders 12 and 13 through which the second finger 11 is pulled out of a contact piece 18 and driven upwardly while the first finger 10 is driven downwardly into an opening 19 of a contact piece 18. With this, a transport cycle is completed. A new cycle is started by the next pressure impulse of the valve 40. 
     When setting up the apparatus, if it is desired to instigate forward driving of the band of series connected contact pieces without the plunger 2 moving downwardly, the axially displaceable pin 35 can be moved by hand to make initial contact with the valve 40. To do this, a force is employed against an opposite end of the axially displaceable mounted pin opposite from the valve which moves the axially displaceable mounted pin 35 against the force of the spring 51. The lateral pin 34 is affixed by means of a threaded screw 52. 
     The stroke position and stroke travel of the cylinder 12 is limited by spacers 53 and 54. The cylinder 13 is screwed onto the base frame 1 by means of a headed screw 55. This headed screw 55 can be moved in a slit 56 so that a position of the cylinder 13 can be controlled. A shoe 57 is slid onto the end of each of the first and second finger 10 and 11 which has portions which can be easily inserted into the respective sizes and shapes of the openings 19 of the contact pieces 18. 
     FIG. 10 shows an alternate embodiment for controlling the control valve 45. In this alternate embodiment, a slide 49 has an elongated cavity 82 defined by end surfaces 83 and 84. The cylinder 12 of the first finger 10 moves between these end surfaces 83 and 84. Strikers 85 and 86 in the form of bolts which can be adjusted in the Z and Y directions protrude out of opposite sides of the cylinder 12. In this manner, the stroke length as well as the stroke position of the cylinder 12 on the piston rod 20 can be varied. When the cylinder 12 is moved with the piston rod 20 the length-adjustable strikers 85 and 86 strike against the end surfaces 83 and 84 and thereby shove the slide 49 which is coupled to the control valve 45. 
     In another alternate embodiment which is represented in FIG. 11, the second finger 11 is not pneumatically or hydraulically moved, but rather mechanically. In this embodiment, a holding element forming the finger is constructed as a simple lever 87 which is rotatably mounted on the ground frame 1 with a head end 88 having a nose 90 directed in the working direction of a pressing spring 89. On a side of the nose 90 opposite the forward direction Z there is a ramp 91 which glides over crimping claws 70 of the contact pieces 18 as the contact pieces 18 are moved in the forward direction Z so as to rotate the lever 87 against force of the pressing spring 89 upwardly. After gliding over the crimping claws the lever 87, with its nose 90, falls downwardly behind the crimping claws 70 and thereby ensures that the band of series connected contact pieces is not inadvertently pulled out of the apparatus, for example from weight of a hanging loop developed between the apparatus and a contact piece roll. This reverse travel preventer is particularly uncomplicated in its construction and is reliable in operation. 
     The separating knife 9, which works with a knife anvil 58, as well as the wire crimper 8 are tightly, and unadjustably, attached to the plunger 2 by means of headed screws 61 and 62. On the other hand, the insulation crimper 7, as opposed to the wire crimper 8, is positioned to be adjustable in its depth. For this purpose, a second threaded bolt 59 is arranged under the threaded bolt 30 which is adjustable by means of a second worm 60. With this the stroke position of the insulation crimper 7 can be adjusted. 
     A bridge 63 is screwed to the front of the base frame 1 that, together with the plunger 2 defines a channel 64. A slide 65 is set in this channel 64 which presses against a compression spring 66 which engages a supporting piece 67 screwed to the bridge 63 and which can be moved in the direction of the crimper anvil 33. Two rotatable jaws 68 which are spread apart through spring force are mounted on the slide 65 and are caused to rotate together by forked shaped ledges 69 when the plunger 2 moves downwardly. When doing this, the jaws 68 grab a lead 75 that lies on the cylindrically concaved support surface 80 of a lower part 74 and centers it such that it is properly positioned with regard to the crimping claws 70 of a contact piece 18. With further downward movement of the plunger 2, an edge 71 of the plunger 2 strikes an edge 72 of the slide 65 and shoves the slide 65 against the force of the spring 66 downwardly. Thereby the two jaws 68, with the lead held between them, moves further downwardly so that they contact the lower part 74 which is also shoved downwardly against a force of the spring 73. In this manner, the lead 75 is placed between the U or V formed upwardly extending crimping claws 70 of the contact piece 18. With further downward movement of the insulation crimper 7 and wire crimper 8 the upwardly extending crimping claws 70 are bent to such an extent that they tightly surround and grab the uninsulated wire end portion and the insulation sheath of the electrical lead. With upward movement of the plunger 2, edges 76 of the jaw 68, which lie between the axes 81, strike a pushing piece 77 which, in turn, is supported by the supporting piece 67. With this, both jaws 68 are pivoted further apart. 
     It will appreciated by those of ordinary skill in the art that the electrical lead end portions do not need to slide between the jaws when they are laid between the crimping claws because the axes of the jaws are movable against the force of a spring in the direction of the contact pieces. This movement takes place first when the lead end portions are gripped by the jaws. 
     It will also be recognized that it is advantageous to have a spring biased lower part to serve as a platform for the lead and against which the closing jaws of the slide ride. 
     It should be recognized that the arrangement of the jaws on a spring biased slide with edges in the direction of the support plug lying between their pivot axes for contacting the base pushing piece makes possible the spreading of the jaws without a spring arranged exactly in the area of these jaws. Also, it is advantageous for the pushing piece to be rectangularly formed and to place notches on the edges of the jaws which contact the rectangular pushing piece. The edges of the rectangular pushing piece grip in the notches so that coupling between the pushing piece and the jaws is locked. 
     The rectangularly formed pushing piece and supporting piece form a support piece over which the jaw mounted, spring biased, slide glides. The support piece is screwed onto a bridge which forms a guide on the front of the base frame for the plunger. 
     It should be understood that in order to vary the separation of the jaws a loose pushing piece is positioned between the support piece and the jaws. This loose pushing piece is easily removed and can be replaced by a pushing piece of another size. 
     With another advantageous embodiment of the invention an edge of the slide protrudes into a movement area of an edge of the plunger and the space between these edges is larger than the stroke of the plunger necessary for closing the jaws. With such an arrangement, it is ensured that a lead will be first centered by the jaws and will only be laid between the crimping claws after a delay to allow such centering. This provides the further assurance that the jaws, when they close together, do not contact an edge of the lead supporting lower part. 
     In order to be able to drive the free ends of the jaws as near as possible to the supporting platform of the lower part in order to positively grip the lead, the supporting platform has a concave cylindrical shape whose radius corresponds to that defined by the ends of the rotatable jaws. 
     It will be further understood that by making the transporting first and second fingers as extensions of pneumatically or hydraulically driven pistons of two piston cylinder systems the arrangement has few driven parts such that the driven parts have small masses. Thus, the transporting arrangement operates with a small expenditure of energy. 
     In order to keep the control system uncomplicated, it is useful that the pneumatic or hydraulic connections to the cylinder for the forward and rearward transport communicates with a cross connection coupled to corresponding connections of another cylinder. 
     Also, it will be understood by those of ordinary skill in the art that a first cylinder with a first finger for shoving the contact pieces driven by a pneumatic or hydraulic piston rod makes control of the system for transporting the contact pieces uncomplicated and reliable. Also, the first cylinder, is additionally supported by a pin which slidably engages the base frame. In this manner, the cylinder and its piston are prevented from rotating. It is advantageous that the cylinder is affixed to the pin and that the pin is slidably mounted in a bore of the base frame. The second cylinder of the second finger is screwed to the base frame. 
     In order to make the size and shape of the finger independent of the size and shape of the opening in the contact piece, a shoe is placed on the free end of the finger. With this arrangement, the apparatus can be used with many different arrangements of contact pieces. 
     A further particularly advantageous aspect of the invention is that the plunger activates a valve which provides a pressure medium to a control valve which, in turn, drives the pistons of the fingers. The control valve, on the other hand, is controlled by a control pin coupled to the cylinder of the first finger which rides in an elongated cavity, elongated in the transport direction, of a slide. In addition, the control valve is coupled to a further valve which provides a pressurized medium to drive the cylinder of the first finger. Such a control is uncomplicated in construction and because of its uncomplicated structure is reliable and functional. This is particularly true when the pressure medium is pressurized air. 
     In another particularly advantageous embodiment of the invention the control valve is controlled by strikers extending from opposite sides of the cylinder of the first finger which are adjustable in the transport direction and in the opposite, or return, direction. In this regard, the adjustable strikers protrude in an elongated cavity of a slide and move the slide to activate the control valve by striking against respective end surfaces forming the cavity. 
     It is particularly advantageous that the control valve is activated by a plunger via a linearly movable pin which can also be moved by hand manipulation. With this arrangement, it is possible, when adjusting transport of the contact pieces, to activate the transport system without the plunger being moved in the base frame. This provides an improved reliability. 
     In order to protect the pressure medium lines, particularly those which present an obstruction when the apparatus is set up or can be easily damaged, the pressure medium lines between the slide valve and the cylinder of the piston rod are bored at least partially in the base frame. Also, it is advantageous to provide a hollow chamber in the base frame as a storage, or surge tank, for the pressurized medium. In this manner, pressure changes in the pressure line system can be smoothed out. 
     In another embodiment of the invention, it is advantageous that the holding element is rotatably or movably mounted at an otherwise fixed position and that it has a spring biased finger whose leading end has a ramp on a side thereof facing opposite the forward transporting direction for engaging an edge formed on a contact piece after a successful forward shoving stroke. In this manner, the band of series connected contact pieces is prevented from sliding out of the apparatus when the first finger is traveling in the reverse direction, for example from being pulled out by weight of a contact piece chain hanging from the machine. This embodiment provides an uncomplicated construction and effective mechanism if the finger is constructed as a pivotal simple, or single-arm, lever whose head, or leading end in the biasing direction of the spring, has a nose thereon with ramp on one side and a square edge on the other.