US2398476A - Punching apparatus - Google Patents

Description

' April 16, 1946.

N. H. SWANSON PUNC HING APPARATUS Filed Jan. 29, 1945 s Sheets-Sheet 1 April 16, 1946.

N. H. SWANSON PUNCHING APPARATUS Filed Jan. 29, 1945 5 Sheets-Sheet 2 'N. H. SWANSON PUNGHING APPARATUS April 16, 1946.

Filed Jan. 29, 1945 5 Sheets-Sheet 3 IIVI/f/VTOR /1/. H SWAA/SO/V Patented Apr- ,16, 1946 UN HE D STATES FAT-ENT OFFICE f r 2,398,476 n a p 1 PUNCHING APPARATUS:

Nils H; Swanson, Zion, Ill.,-assi'glnor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New'York ApplicationJannary 29, 1945, Seriah No.- 5575 021 (Cl..I6489)" 'l'Claims.

This invention relates to punching apparatus and more particularly to an apparatus for punching solder pellets from a strip of solder.

Crystals having piezo-electric characteristics are utilized in maintaining frequency stability in electronic circuits. One type of shock-proof crystal mounting involves the soldering of lead wires to the crystal surfaces which have been treated with a metallic coating to make contact with the crystal surface and to accept the solder of the lead Wire. In one method of crystal mounting the amount of solder used is very critical and has to be. of a quantity within narrow definite limits. For example, in one method of soldering lead wires to crystals a predetermined amount of solder in the form of a pellet is dropped into a crucible of molten lead. The pellet begins to soften butbefore it fuses with the surrounding molten lead, the operator touches. it

with the fluxed end of a headed lead wire to which the softened lead pellet adheres. Then the lead wire is soldered to the metallic coating of the crystal surface. decreases, the difiiculty of measuring the solderv pellet and sighting it in the crucible before it. fuses with the molten solder increases. On very small crystals the size of the lead pellet is smaller than the head of a pin.

An object of this invention. is to provide an' efficient and effective apparatus for forming pellets of a predetermined size and to so direct them that they will always strike the same spot in a crucible of molten lead.

In accordance with one embodiment of this invention a strip of solder tape is guided into a punching machine actuated by a manually operated lever, which, moving through a certain distance operates in a certain sequence two punches and a pair of rollers for advancing the tape. As the lever is moved, the punches are alternately forced up against a spring by teeth on a ratchet Wheel, the punches being released when the teeth disengage with the cocking lugs on the Punch bolt, the punching force being. the energy stored in the compressed spring. After the pellet is punched out, it is forced ofi'the punch. by its own momentum due to an abrupt stop of the punch bolt. The pellets are guided down a spout o that each pellet as it is punched out will land on the same predetermined location.

A better understanding of the invention will be had by reference to the following detailed description when considered in conjunction with the accompanying drawings, wherein Fig. 1 is a fragmentary plan view of an appa- As the size of the crystal punched by the apparatus.

ratus embodying the: features of the invention with the cover plate removed;

Fig; 2 is a front elevation of the apparatus shown. in Fig. 1

Fig. 3 is a sectional View taken on the line 3-3 Fig. 4 is. a vertical sectional view taken on th line 4-4 of Fig. 2;v

Fig. 5 is a vertical sectional view taken on the line 5--5'of Fig. 2; and

Fig. 6 is a vertical sectional view, partly in elevation, taken onsthe line 6-6 of Fig. 2.

Referring to the drawings, the apparatus is mounted on a base member ll (Figs. 2, 4 and 6) which supports a main block l2 and a platform l3 (Figs. 1,2 and 3) upon'which'a hub I4 is rotatably mounted at right angles to the platform l3 for carrying; a spool or pad of coiled solder strip I5 fromv which solder pellets are to be To help maintain tension on the solder strip a roller I9 is rotatably mountedgon the platform I3 which presses the solder strip aga-inst a die supporting block 2| to frictionally retard the strip. The section of the base- It upon which the platform I3 is secured is disposed at a slight angle from the main block l2 to allowthe solder strip l5 to be fed obliquely across a die plate-l6 beneath a pair of punch bits. H- and I8. Because of the oblique feed, the

' r-holes punched in the solder strip are staggered and the. optimum use of the material strip is obtained.

Secured to the. front of the main block i2 (Figs. 1, 2,. 3 and 4.) is a. die supporting block 2! with a suitable recess 22 therein, in which the die plate It is. nested. The die plate is provided with die apertures 23 and 24. having conical counterbores on theside away from the main block. A stripper and guide plate 25 with a diagonal groove 26 across one face, and with apertures to guide the punch bits I! and I8, is fitted between the die plate l6 and the front of the main block I 2, with the groove 2'6'facing the die plate l6 to form a rectangular shaped aperture running diagonally between the guide plate 25' and the die plate to receive and guide. the solder strip.

The reciprocable punch holders 3| and 32 (Figs. 1', 2}. 3' and 4) pass. through and are held in positi'on and guided by the apertures 33 and 34 in plate 35' and bores. 36 and 31 in the block [2. At about the center of their lengths the punch holders have. annular collars ll and 42 (Fig. 4) integrally formed therewith which slideably lit the. bores. 36"and 31. The collars 4| and 42 are provided with projectinglug 43 and M, respectively, that slide in slots 45 and 46 cut into the main block l2 to prevent rotational movement of the punch holders. The punch holder 3| has associated with it two helical compression springs 41 and 49, which encircle the punch holder on either side of the collar 4|. Two similar springs 48 and 59 encircle the punch holder 32 in the same manner. The energy of the springs 41 and 48, when compressed, acting between thecollars GI and 42 and the plate 35, is the actuating force that moves the punches against the solder strip. By applying their expansive pressure between the collars 4| and 42 and the bushing inserts and 52, the springs 49 and 50 restore the punches to their normal position. In the normal position the punches float between the two encircling compression springs to keep them clear of the die apertures when the solder strip is being advanced.

The punch bits I! and 3 are pinned into holes at one end of the punch holders by pins 53 and 54 (Fig. 4) respectively. The other endof each of the punch holders is. threaded'to receive cooperating lock nutsv 55 and 59 which serve as abutments, as will be described hereinafter. The punches are loaded and released by the action of ratchet wheels 51 and 58 (Figs. 1 and 4) the teeth of which engage the lugs 43 and 44, first com pressing the springs 47 and 49' and loading the punches, then, when the teeth disengage with the lugs 43 and 4 3, releasing the punches for movement against the solder strip, the momentum of the punches forcing them through the solder strip at high speed. After perforating the solder strip andpassing through the die, the punches are brought to an abrupt stopby the nuts 55 and 59 abutting against plate 35. V The nuts 55 and 59 are adjusted to stop the stroke of the punch holders 3i and 32 before their energy is fully absorbed by the springs 49 and 59, at a point between neutral and the normal end of their strokes, thereby providing the necessary abruptness to the stop of the punches. This sudden stop causes the pellets, which are'punched out of the solder strip, to leave the bits of the punches at a high velocity, projecting them into the channels of a spout 5| (Figs. 1, 2, 3 and 4) having a ridge 55 along its centerto form two converging channels 68 and 59 one for each of the punch and die units. The two channels converge into a main channel 69 forming the figure Y, all the channels being substantially V-shaped in cross section. A cover plate 62 (Fig. 2) over the channels prevents the pellets from bouncing out of the spout. The constructional features of thespout are such that upon striking the channels in the spout, the speed of the pellets is reduced considerably and they roll gently down the main channel of the spout landing on a definite spot in a crucible i9 containing molten lead 80. Subsequently punched pellets will always drop on the same spot and at such a speed that the operator is able to sight them as they land in the molten lead and pick them up on the fluxed end of a headed lead wire before the pellet fuses with the surrounding molten lead. The sudden impact and the abrupt stop of the punches in this invention prevent the tiny pellets from adhering to the punch bits, which is a common occurrence where soft material such as solder is punched by the relatively slow moving punches in ordinary punching machines.'

The ratchet wheels 51 and 58, which cock and release the punches, are rotatably mounted on a shaft 63 journalled in the main block 12, which has a recess 54 (Figs. 1 and 4) therein to accommodate the ratchet wheels 51 and 58. These ratchet wheels are fixed to the shaft 63 so that any rotational movement of this shaft is imparted to them. The other end of the shaft 63 projects out of the block l2, and, on this projecting end are mounted an operating lever 55 (Fig. 1) and a ratchet wheel 56, the teeth of which cooperate with a pawl fil resiliently attached to the lever 95 (Fig. 6) It is apparent from the drawings that clockwise rotation of the shaft 63 (looking at Fig. 6) can be imparted to it by first rotating the lever 65 counterclockwise away from a stop pin Tl until the pawl 91, urged by a spring 12, engages one of the teeth on the ratchet wheel '65, then reversing the rotationof the lever until it strikes the stop H, thus giving the shaft 63 suflicient clockwise rotation to complete one cycle of operation of the apparatus.

Intermittent advancement of the solder strip is provided as follows:

A recess 13 (Figs. 1 and 6) is formed in the main block 12 to permit the rotatable mounting of toothed wheel I4 on the shaft 63. The teeth of this wheel engage a shoulder at one end of a rectangular notch 15 in a rod iii, which is reciprocably positioned in the circular apertures Fl and '88 in the main block I2. The combined action of a coiled compression spring BI and the rotation of the wheel 14 imparts a reciprocatory movement to the rod 19, which action is utilized to operate a mechanism, hereinafter described, for the intermittent advancement of the solder strip I5 across the die plate. One of the opposing surfaces against which the spring 8| acts is the plate 35, the other abutting surface is a washer 82 held in place by a nut 83 screwed onto the end of the rod 16 which is threaded. At the other end of the rod 16 (Fig. 3) a pawl 84, moving in a transverse aperture 85 in the rod, is forced into engagement with a ratchet wheel 89 by a curved flat spring 91 fixed to the end of the rod 76, the free end of the spring being channel formed to cooperate with the wedge-shaped head of thevpawl 84 to prevent the pawl from rotating about its longitudinal axis. Rotational movement of the rod 16 is prevented by a projecting pin 98 (Fig. 6) integrally formed with the rod and slidably positioned in a slot 89 cut into the main block I2. The slot is long enough to allow the necessary freedom for the reciprocation of the rod. As the rod reciprocates, intermittent clockwise rotation (looking at Fig. 3) is imparted to the ratchet wheel 89 by the action of the pawl 84 on the teeth of the wheel. To prevent counterclockwise rotational slipping of the ratchet wheel 86, another pawl 9|, fitted into a hole formed in the main block I2 is urged by a spring 92 into engagement with the teeth of the wheel. The movement of the ratchet wheel 86 is transmitted to a knurled feedroll 93 (Figs.'1 and 5), both the ratchet wheel and the roll being mounted on the opposite ends of a shaft 94 whose center portion is journalled in the main block l2 as shown in Fig. 5. The knurled periphery of the feed roll contacts one surface of the solder strip 55, which is gripped between the feed roll and a companion roll 95. The companion roll 95 is rotatably mounted on a stud shaft Hil afiixed to the end of a rod 98 slidably positioned in the block 12. A helical compressed spring 96 encircles the other end of the rod 98, exerting a force between a collar 9'! and the plate 35. This force transmitted through the rod urges the roll 95 against one side of the solder strip maintaining a substantially constant pressure on it. As

the feed roll is intermittently rotated, the solder strip is advanced in steps. The timed relation between the movement of the punches and the feed advancement mechanism is such that the punches, although alternate in operation, are both in a floating non-operating position during that portion of the cycle in which the solder strip is advanced.

An offset I03 (Figs. 1 and 6) in the top of the main block I 2 in combination with a curved band I04 screwed to the block provides a cavity for the accumulation of the perforated material strip as it leaves the apparatus.

What is claimed is:

1. A punching apparatus comprising a punch and die, means for advancing a material strip between said punch and die, resilient means associated with said punch to actuate it against said material strip, resilient means associated with said punch to restore it to its normal operating position, means cooperating with said punch to load and release said punch, means associated with the material advancing means to synchronize the latter with the punch, and meansfor abruptly stopping said punch after penetrating said material strip.

2. A punching apparatus comprising a punch and die, means for advancing a material strip between said punch and die, resilient means associated with said punch to actuate it against said material strip, resilient means associated with said punch to restore it to its normal operating position, means cooperating with said punch to load and release said punch, and means for abruptly stopping said punch after penetrating said material strip.

3. A punching apparatus comprising a punch and die, means for advancing a material strip across the die, a compression spring associated with said punch to actuate it against said material strip, a second compression spring associated with said punch to restore it to its non-operating position, a ratchet wheel cooperating with said punch to load and release said punch, means associated with the material advancing means to synchronize the latter with the punch, and means for abruptly stopping said punch after penetrating said material strip.

4. A punching apparatus comprising a punch and die, means for advancing a material strip across the die, a compression spring associated with said punch to actuate it against said material strip, a second compression spring associated with said punch to restore it to its non-operating position, a ratchet wheel cooperating with said punch to load and release said punch, means associated with the material advancing means to synchronize the latter with the punch, means for abruptly stopping said punch after penetrating said material strip, and means to direct the course of the exit of the product from the apparatus.

5. A punching apparatus comprising a punch and die, a compression spring to actuate the said punch, a second compression spring to restore the punch to the non-operating position, a ratchet wheel cooperating with said punch to load and release said punch, a material strip advancing means comprising a toothed wheel, a rod cooperating with said toothed wheel to reciprocate the rod as said wheel is rotated, a ratchet wheel, a pawl fixed to said rod to cooperate with said ratchet wheel and a roller operatively connected to said ratchet wheel and in surface engagement with said material for intermittently advancing the material, a companion roll in contact with said material strip, a resilient means for maintaining a substantially constant pressure on said last mentioned roll, a common shaft to synchronize the material advancing means with the punch, means for abruptly stopping said punch after penetrating the material strip, and a covered Y-shaped spout with V-shaped channels to reduce the speed of the punched pellet and to direct the course of its exit from the apparatus. 6. A punching apparatus comprising a punch and die, means for advancing a material strip between said punch and die, resilient means associated with said punch to actuate it against said material strip, resilient means associated with said punch to restore it to its normal operating position, means cooperating with said punch to load and release said punch, means for abrupt- 1y stopping said punch after penetrating said material strip, means to direct the course of the product from the apparatus, and a receptacle disposed in the path of said product to receive said product.

7. A punching apparatus comprising a punch and die, means for advancing a material strip between said punch and die, resilient means associated with said punch to actuate it against said material strip, resilient means associated with said punch to restore it to its normal operating position, means cooperating with said punch to load and release said punch, means for abruptly stopping said punch after penetrating said material strip, means to direct the course of the product from the apparatus, and a receptacle containing molten lead disposed in the path of said product to receive said product.

NILS H. SWANSON.

Images