GB2135620A - Cut-clinch mechanism for variably spaced component leads - Google Patents

Abstract

A cut-clinch mechanism for cutting and forming the leads of electronic components A-E inserted into the openings in a printed circuit board has a fixed cut-clinch head 12 supporting a movable cut-clinch head 14 with a bi-directional drive means for incrementally moving the heads toward and away from one another to accommodate variable spaced component leads. The heads can preferably be rotated to accommodate components having varying angular dispositions relative to the board. <IMAGE>

Description

SPECIFICATION Cut-clinch mechanism for variably spaced component leads This invention is concerned with a mechanism for cutting and clinching the leads of electrical components inserted into the openings in printed circuit boards.

In the assembly of electrical components to printed circuit boards, for a given board circuit, a plurality of components must be applied that have different dimensions and thus different spacings between the leads of the components. The component leads are either manually or automatically inserted into preselected holes in the board. After the leads are inserted into the board, a cutting and clinching unit positioned below the board will cut off the excess lead and bend or form (clinch) the remaining lead to securely attach the component to the board. After all the necessary components have been assembled to the board, the entire assembly will go through a wave solder process to complete the board assembly.

This assembly process can be semi-automatic by the operator having components supplied in a preselected sequence through a programmed supply source such as illustrated in U.S. Patent No. 4,273,393. With the board fixed to a station available to the operator, the preselected component is inserted into the board at a location identified to the operator and a cut-clinch unit, programmed to cut the clinch the preselected component, is activated by the operator to move into position and cut and clinch the component leads to temporarily attach the component to the board. Examples of such cut-clinch units are illustrated in U.S. Patent Nos. 4,288,914 and 4,292,727. Additionally, such cut-clinch units are moved toward and away from the board and can rotate with respect to the board since the angular disposition of the components inserted into the board vary with respect to one another.An example of this type of unit is illustrated in U.S.

Patent No. 4,153,082.

The above types of cut-clinch units, however, have not been designed so that the cut-clinch mechanism can automatically accommodate components having variable spaced leads and perform the cut-clinch function on incrementally variable speed leads in response to a programmed control.

The present invention provides a mechanism for cutting and clinching variable spaced leads of electrical components that have been inserted into a printed circuit board, comprising a support housing, a fixed cut and clinch head mounted on said support housing and having means to cut and clinch component leads, and a movable cut and clinch head having means to cut and clinch component leads, the movable head being carried on said fixed head for movement toward and away from said fixed head by a drive mechanism adapted to move said movable head incrementally toward or away from said fixed head so as to space said heads a predetermined distance from one another to accommodate cutting and clinching variable spaced leads of the components assembled on the board.

Preferably the drive mechanism of a mechanism according to the invention is programmable.

Preferably the fixed head of a mechanism according to the invention is carried on a piston mounted in a cylinder for up and down movement of both heads toward and away from the board.

Conveniently said cylinder is rotatably mounted in the support housing to contact with a drive means to rotate said cylinder, piston and said heads to accommodate cutting and clinching the leads of components having varying angular dispositions with respect to one another on the board.

There now follows a detailed description, to be read with reference to the accompanying drawings of a cut and clinch mechanism embodying the invention and illustrative thereof.

It will be realised that this mechanism has been selected for description by way of example and not of limitation of the invention.

In the accompanying drawings:~ Figure 1 is a side elevational view of the cut and clinch unit, partially in section, positioned adjacent the printed circuit board and illustrating the various components with their respectively spaced leads which can be assembled to the board; and Figure 2 is an exploded view of the cut-clinch mechanism of this invention.

Attention is now directed to Figure 1 of the drawings which shows the illustrative cut-clinch mechanism 10 having a fixed head 12 and movable head 14 positioned below a printed circuit board (B) to cut and clinch the leads of components extending through the openings in the board (such as components A to E are illustrated in Figure 1). The fixed head 12 has a pair of flanges 1 6 upon which rails 1 8 are mounted. The movable head 14 has flanges 20 carrying rails 22 that engage rails 18 so that the heads 12 and 14 can move toward and away from one another.

Attention is now directed to Figure 2 which illustrates in exploded view the mounting for the cut-clinch mechanism that enables the heads 12 and 14 to be moved toward and away from the board (B), rotated at 900 increments and positions the movable head 14 with respect to the fixed head 12 all under a programmed control.

The fixed head 12 is secured to a cup shaped piston 28. The piston 28 has a circumferential flange 30 secured to the flange 16 through a plurality of openings 32 on flange 30 and openings 34 on flange 16. The piston 28 is carried in a cup-shaped cylinder 38 which is positioned in an opening 40 in a support housing, viz. a spider 42. The bottom 44 of the cylinder 38 has a bearing engagement with a surface 46 of the spider 42 (see Figure 1) so that the cylinder 38 can rotate with respect to the spider 42 for reasons that will become apparent hereinafter.

The piston 28 is sealed within cylinder 38 by means of an O-ring 48. An air line 50 passes through an opening 52 in spider 42 and into recess 54 around a collar portion 56 of the cylinder that is received within opening 40 of spider 42. The air pressure can then pass through an additional opening 58 in collar portion 56 and underneath the piston in a recessed area 60. This air pressure will move the piston 28 upwardly to move the cut-clinch heads upward to an operative position beneath the board (B). A flange 62 of the cylinder 38 receives plates 64 positioned within notches 66, 68 on the sides of the piston 28. This plate and notch connection between the piston and cylinder permits the piston to move upwardly from the position shown in Figure 1 to a position wherein the cut-clinch heads are under the board.

At that time, the plates 64 will bottom out on the bottom 70 of notches 66, 68 limiting further upward movement of the piston 28. A pair of return springs 72 are positioned between pins 74 on piston 28 and pins 76 on cylinder 38 to return the piston to the lower position (head lowered position) after the cut-clinch operation on a given component has been performed. In this manner the cut-clinch heads are free from interfering with the next component insertion operation in the assembly sequence.

An additional O-ring 78 surrounds collar 80 of piston 28 to seal a chamber 82 between the piston 28 and cylinder 38.

The collar 80 is surrounded by a pinion gear 84 and locating disc 86. A housing 88 has a flange 90 and bolts 92 pass through flange 90, pinion gear 84 and locating disc 86 and into the lower end 94 of collar 56 on cylinder 38.

A rack 96 is carried in an opening 98 in spider 42 and is controlled for back and forth movement to rotate the pinion gear 84 and thus the cylinder 38 and the cut-clinch heads with respect to the board to accommodate component leads having different angular dispositions on the board.

The positioning of the rack 96 is controlled by cylinders 100 and 102 carried on a yoke 104. The yoke 104 is pivotted on a bracket 106 secured to the underside of the spider 42. The end 108 of cylinder 100 is secured to the rack and the end 110 of cylinder 102 is carried in a bracket 112 secured to the underside of the spider 42.

Actuation of either cylinder 100 or 102 will pivot yoke 104 and move the rack 96 on pinion 84 causing rotation of cut-clinch mechanism. This rotational positioning of the cut-clinch mechanism is in 900 increments.

To assure that this drive for the cut-clinch mechanism is stopped and held at accurate 900 increments, a centreing mechanism 114 is provided. A bracket 11 6 is slidably carried on bracket 106 and has a nosepiece 118 carried in a space 120 between a bracket 122 and the spider 42. An air cylinder 124 acts against nosepiece 11 8 to slide bracket 11 6 toward the locating disc 86. This will engage a nose portion 126 into a required notch 128 in locating disc 86 to accurately position the cut-clinch mechanism in 900 increment and lock same in that position.

The mechanism for incrementally positioning the movable cut-clinch head 14 with respect to the stationary head 12 includes a rack and pinion drive. The rack 130 is secured to bracket 132 on the underside of flange 20 of the movable head 14. The pinion 134 is on a shaft 136 that passes down through the piston 28, cylinder 38 and housing 88 (see Figure 1). The shaft 136 is positioned in a bearing 138 held in a collar 140 by retaining rings 142, 144. The collar 140 is secured to the flange 30 of piston 28 by set screws (not shown) located in the openings receiving pins 74. The lower end 146 of pinion shaft 136 is positioned in a sleeve bearing 147 pressed into collar 80. The pinion shaft 136 is secured to a collar 145 of a flexible drive coupling 148 by lock screw 1 50.A lower collar 1 52 of the coupling 148 is secured by lock screw 154 to a shaft 156 of a bi-directional drive 158 comprising solenoid means, viz. a pair of rotary solenoids 1 60, 1 62. The drive 158 is secured through the interconnection of a flange 164 on housing 88 and the flange 166 on the drive. It can thus be seen with the above described drive for the movable head, a programmed energizing of either solenoid 1 60, 1 62 will rotate the pinion 134, thus providing a programmable rotational drive member to move the rack 130 and movable head to the predetermined required increment of spacing to properly space the cut-clinch heads for a given component lead spacing in the component assembly sequence.

Due to the force required in the direction of the inward clinch of the component leads, there is a certain amount of reaction force tending to separate the cut-clinch heads. To assure that the heads do not move with respect to one another in the clinch operation, a brake mechanism 168 surrounds shaft 136 and locks the pinion against rotation.

The brake mechanism 1 68 comprises a magnet 170 carried in a housing 172 secured to the collar 140 by bolts 174. A plate 176 is secured by a set of leaf springs 178 to a collar 180 secured by set screws 182 to the pinion shaft 136. When the pinion shaft 136 is in the desired position of rotation (and thus the heads properly spaced), the magnet 170 is energized pulling the plate 176 against housing 172 to lock the plate 176 and thus the collar 180 and shaft 136 against rotation.

It can thus be seen that the drive mechanism described can move the cut-clinch heads toward and away from the board and rotate the heads 3600 to accommodate the varying angular disposition of the component leads inserted into the board. Further, the movable head can be incrementally indexed toward or away from the fixed head to accommodate variable centre spacing of the components assembled to the board.

Claims (11)

1. A mechanism for cutting and clinching variable spaced leads of electrical components that have been inserted into a printed circuit board, comprising a support housing, a fixed cut and clinch head mounted on said support housing and having means to cut and clinch component leads, and a movable cut and clinch head having means to cut and clinch component leads, the movable head being carried on said fixed head for movement toward and away from said fixed head by a drive mechanism adapted to move said movable head incrementally toward or away from said fixed head so as to space said heads a predetermined distance from one another to accommodate cutting and clinching variable spaced leads of the components assembled on the board.

2. The mechanism of claim 1 wherein said drive mechanism is programmable.

3. The mechanism set forth in either one of claims 1 and 2 wherein said drive mechanism is positioned in said support housing and has a programmable rotational drive member and means to convert rotational movement thereof into the lateral movement of said movable head toward and away from said fixed head.

4. The mechanism of claim 3 wherein said rotational drive member comprises solenoid means which drives a rack and pinion drive connected to the movable head.

5. The mechanism of claim 1 wherein said drive mechanism includes a rack carried on said movable head engaging a pinion carried on a shaft driven in either a clockwise or counterclockwise direction by a pair of solenoids.

6. The mechanism set forth in any one of the preceding claims wherein said heads have interengaging rails on which said movable head is mounted for movement toward and away from said fixed head.

7. The mechanism of any one of the preceding claims wherein said fixed head is carried on a piston mounted in a cylinder for up and down movement of both heads toward and away from the board.

8. The mechanism of claim 7 wherein said cylinder is rotatably mounted in the support housing to coact with drive means to rotate said cylinder, piston and said heads to accommodate cutting and clinching the leads of components having varying angular dispositions with respect to one another on the board.

9. The mechanism of claim 5 wherein said fixed head is carried on a piston mounted in a cylinder for up and down movement of both heads toward and away from the board and wherein said shaft passes up through said piston and is freely rotatable therein.

10. The mechanism of claim 5 wherein said fixed head is carried on a piston mounted in a cylinder for up and down movement of both heads toward and away from the board and wherein the mechanism comprises brake means which coacts between said shaft and said piston to lock said shaft against rotation during the operation of said means to clinch the component leads.

11. A mechanism for cutting and clinching variably spaced leads of electrical components constructed arranged and adapted to operate substantially as hereinbefore described with reference to the accompanying drawings.