US2516017A - Power press - Google Patents

Description

y 8, 1950 E. D. PERRY 2,516,017

POWER PRESS Filed March 11, 1947 47 INVENTOR.

Edwam/D'PerV Patented July 18, 1950 UNITED ,s ATEs PATENT OFFICE Edward D. Perry, East Greenwich, R. I., assignor to Sterling Engineering 00., Providence, It. I.,

Application March 11, 1947, Serial No. 733,774

8 Claims. (01'. 164-4021 This invention relates to punch presses, and more particularly to a crank-operated punch press having a C or gap such as is generally used in the metal stamping industry for blanking, piercing, trimming, forming, and drawing sheets or strips of metal or other materials. a

In the crank-operated press illustrating the present invention, the punch-operatin slide is driven by a connecting rod located above the crank shaft whereby the center of gravity of the press is kept low and a top-heavy construction is avoided.

One object of the present invention is to provide a punch press of the above nature, in which the punch-carrying slide is made in the form of a wide yoke having bearings on a pair of forward pillars which insure absolute alignment of the punch and die, and will eliminate the necessity of using die sets which are now commonlyemployed in previous types of punch presses for holding the die and punch in alignment. In fact, the press itself is made with great precision, and may be aptly termed a power-actuated die set.

A further object is to provide a punch press of the above nature which will be simple in construction, smooth in operation, inexpensive to manufacture, easy to install and manipulate, compact, ornamental in appearance, and very efficient and durable in use.

With these and other objects in View, there has 6 been illustrated on the accompanying drawing one form in which the invention may conveniently be embodied in practice.

In the drawing,

Fig. 1 represents a side elevation of a punch press embodying the present invention.

Fig. 2 is a front elevation of the same, with the motor removed and with certain parts broken away and shown in section.

Fig. 3 is a plan view of the same.

Fig. 4 is a transverse sectional view of the same, taken along the line 4--4 of Fig. 1, looking downwardly upon the top of the die holder.

Fig. 5 is a fragmentary sectional longitudinal view taken along the line 55 of Fig. 4, showing the means for interchangeably clamping the die plate to the die shoe.

Fig. 6 is a transverse sectional view, taken along the line 66 of Fig. 1, looking downwardly upon the top of the cross member.

Fig, 7 is a longitudinal sectional view, taken along the line of Fig: 3, through the cross member and the lower part of the punch-carrying slide.

One of the conventional punch presses now in common use consists of a frame, usually made from cast iron, and having a lower bed on which is mounted abolster, to which the various special dies for performing the required operations are clamped. (See Patent No. 428,414., to Riley, May 20, 1890.)

At the top of the frame of such a press there is a crank shaft having a fly wheel at one end, usually at the right of the operator. This fiy wheel contains asingle revolution clutch and is adapted to idle on the shaft, except when the clutch is manually engaged, at which time the shaft will make one revolution and then come to a stop.

The fly wheel, which stores energy and assists in performing the required work, is quite heavy, and relatively large in diameter.

Moreover, since the fly wheel is mounted at the top of the press frame, the structure is comparatively top heavy, and cumbersome to move or install. Moreover, when the fly wheel is rotated at fairly high speed, it is sometimes not completely balanced and hence, due to its elevated location causes undue vibration of the press. The fly wheel also projects forwardly so as to interfere with the movements of the operator, and is always a constant source of danger.

When an individual motor drive is used with such a conventional press, the motor is located either above the fly wheel placing the center of gravity still higher, or projects from the rear of the press, adding to the general instability.

The reciprocating slide in some conventional types of punch press is located below the crank shaft and has means for holding the punch for cooperating with the die clamped on the bolster beneath it. This slide is operated by the crank through a connecting rod which is made adjustable in length, so that compensation could be made for the varying heights of the different special dies and the varying lengths of the punches. Insuch a punch press, the means for adjustment is not easily accessible to the die setter, and is structurally weak, particularly when adjusted to its extreme length.

Again, the slide in some types of a punch press includes a pair of V-ways Working in gibs, which are bolted to the frame, and the ratio of the bearing length of the gibs and the distance between the gibs is quite small, seldom over 2:1. Moreover, as the slide always projects beyond the bottom of the gibs, there is insufficient resistance to unbalanced loads in the dies, causing wear and misalignment to occur.

In fact, this condition has been generally accepted as inevitable, and it was the general custom even on new presses, to use what are known as "pillar die sets, which were produced commercially by several concerns. A die set consists of a die plate, or shoe, and two or more vertical pillars which engage corresponding holes in the punch plate or holder in order to assure proper matching of the punch and die In use, one die set is required for each punch and die combination, and after proper adjustment it remains permanently assembled with its punch and die.

While the use of such die sets was a great convenience they involved considerable added expense, both in the original cost, and for storage space.

By means of the present invention the above and other disadvantages have been overcome,

and a general all-purpose crank-operated punch press has been provided, having a low center of gravity, which is convenient to adjust and operate, and which has precision alignment, so that the use of die sets for accurate work is entirely eliminated and both upper and lower dies will always be accurately located after their initial adjustment has been completed.

Referring now to the drawings in which like reference numerals denote corresponding parts throughout the several views, the numeral II indicates the base of the press, which is accurately bored to receive three vertical posts or pillars I2, I3, Mthe two pillars I2 and I3 being located adjacent the front of the base I I and the pillar It being located at the rear of said base at a point equidistant from the two front pillars I2, I3. Each .of the three pillars I2, I 3, I I is held rigidly to the base I I by means of a pair of nuts I5 located below said base, the same nuts I5 also serving to secure three Z-shaped feet I6, I'I, I8 to the base II.

In order to cause the vertical punch (not shown) to reciprocate with respect to the die (not shown), provision is made of a slide I9,

which is constructed in the shape of a hollow box open at the rear and provided with four corner ears 2!], 2I, 22, 23 which are accurately bored, and provided with bushings 24,25 fitted about the two front posts I2, I3.

It is to be understood that in operation the slide I9 will move up and down and will be guided over its full length regardless of its position by means of the pillars I2, I3.

It will also be understood that the ratio of the length of the slide to the diameter of the guiding pillars is quite large, and is constant regardless of the elevation of the punch-carrying slide.

The bottom of the slide I9 is made'horizontal and is provided with a hole 26 for receiving the shank of any special punch to be used with the press. Provision is also made of a set screw 21 for clamping the punch shank to the slide I9.

Near the top of the slide I9, provision is made of a horizontal pin 28 which is pivotally connected to a connecting rod 29 extending downwardly within the slide I9, and being connected to an eccentric crank pin 30 of a horizontal crank shaft 3 I. In front of the crank shaft 3 I, provision is made of a retaining disk 32, for holding the connecting rod 29 in operating position.

In order to permit access to the retaining disk 32 and the front of the crank shaft 3I, provision is made of a small opening in the front portion of the slide I9, which is closed by a cover 32a. (Fig. 7.)

The front end, of the crank shaft 3 I is journaled ina horizontal cross member 33 which is clamped rigidly upon the two front posts I2, I3, and is locked in this position by means of four keys 34. The crank shaft 3| extends rearwardly and has its rear end journaled at 35 on the upper end of the rear pillar I4.

In order to control the operation of the press, provision is made on the crank shaft 3|, directly behind the cross member 33, of a brake 36 of conventional design, and between said brake and the rear post I4 a fly Wheel 37 is located. Also between the fly wheel 31 and the rear post I4 is a clutch 38, which may be of any suitable design.

Provision is also made of a curved tripping lever 39 having a hand knob 3%, which when pushed outwardly, will start the operation of the press. As a safety precaution, provision may also be made of a second lever 39a having a knob 390 which must also be pushed outwardly by the other hand of the operator before the tripping lever 39 can be moved.

The die bed for the power press comprises aiflat horizontal platform 40, upon which is mounted a split die shoe 4 I. Both the die bed and die shoe have aligned bores shaped to lit the two front pillars I2, I3, so as to hold said parts in vertical alignment with the slide I9. The rear end Ma of the die shoe M is detachably held in operating position by a bolt Mb havinga knurled head M0.

The die bed 9!) also has a shank 42 projecting downwardly therefrom, through a hole in the base II-said shank 42 being threaded and provided with a pair of lock nuts 43, 44' located one above and one below the base I I, whereby the die bed-4D and the base II may be adjusted up and down as a unit upon the pillars I2, I23, as required in accordance with the height of the die and length of the punch.

It should be noted that this arrangement permits ample length adjustment, and that such adjustment is convenient and easy to make. Also there is no weakening of the structure at any position of the die bed because all lateral stresses which may occur are located between the top of the die shoe M and the bottom of the slide I9, and

will be resisted bysaid pillars I2, I3 since the slide I9 and the die shoe 4| are comparatively close together and the alignmentbetween them is maintained by the two posts I2, I3.

It will be understood that vertical stresses which occur between the slide I9 and the die shoe II will be transmitted to the cross member .33 through the crank shaft 3| and will placethe front pillar posts I2, I3 in tension, and the rear post I4 in compression.

Due to the relatively large distances'between the front posts I2 and I3 and the rear post I4, which serves as a fulcrum,-the upward stresses on said front posts will be substantially vertical and will have practically no resultant horizontal component. Consequently, the dies will remain in accurate alignment with the punches at all times.

In order-to permit the finished work'to drop out the die through the die bed 49 into a suitable receptacle (not shown), said bed maybe provided with a central hole beneath said die.

The die shoe 4! is provided with an abutment 43 at the rear thereof, against which a die-plate 45 is adapted to be held by an inclined forward clamp 41 secured in place by a bolt 41a. The abutment 46 is machined at a precise distance from the pillar post holes, so that the die plate 65 will always be properly located with respect to thefront and rear of the press. I

In order to assure correct positioning of the die plate 45 laterally, a keeper pin 48 is provided which engages a slot in said plate to accurately locate it with respect to the post holes.

If an individual drive is to be used, a motor 49 may be located under the bench B, said motor having a drive pulley 50 connected by a belt 5! to a groove 52 in the fiy wheel 37. For larger floor types of presses the motor would be mounted on a frame located in a similar relation to the flywheel,

Operation In preparing a new die for use in this press,

assuming that the actual punch and die have previously been made, the die plate 45 will first be clamped in the press. The punch will then be inserted in the slide l9, and the die will be placed in the die plate 45 and properly aligned with the punch. For convenience, the punch may temporarily be attached by wax or other means to the die plate, and then both the die and the die plate 45 will be removed and permanently fastened together, and will always remain in such relationship thereafter.

It will thus be seen that after any die has been so mounted it may be put in any press of this type and will be ready to operate thereafter without further adjustment, except for height.

One advantage of the present invention is that by locating the motor 49 underneath the fly wheel and having the crank shaft and fly wheel approximately in line with the center of the slide, the center of gravity of the press will be kept relatively low.

A further advantage is that the connecting rod will be maintained in tension during the power stroke, instead of in compression, as was the case in previous conventional types of presses.

A further advantage is that the connecting rod is made of one piece and the adjustment is made by moving the die bed up and down, instead of lengthening the connecting rod itself.

While there has been disclosed in this specification one form in which the invention may be embodied, it is to be understood that this form is shown for th purpose of illustration only, and that the invention is not to be limited to the specific disclosure, but may be modified and embodied in various other forms without departing from its spirit. In short, the invention includes all the modifications and embodiments coming within the scope of the following claims.

Having thus fully described the invention, what is claimed as new, and for which it is desired to secure Letters Patent, is:

1. In a punch press, a base, two forward and one rear upstanding spaced pillars fixed directly on said base, a cross member fixed to said two forward pillars and extending at right angles thereto, a punch-carrying slide embracing said cross member and mounted on said two pillars, a crank shaft journaled in said fixed cross memher and being journaled at its rear in a bearing on the top of the rear pillar, means to drivingly connect said slide with said crank shaft, and a die-holding bed located beneath said slide.

2. The invention defined in claim 1, in which provision is made of means slidably mounting said die-holding bed upon the lower portion of said forward pillars, a die plate on said die bed, and means for clamping said die plate accurately in operating position on said die bed.

3. A punch press as defined in claim 1, in which said slide has two pairs of pillar bearings, one pair being disposed above said cross member and one pair below said cross member.

4. A punch press as defined in claim 1, in which said die bed is slidably connected to said forward pillars and has a central supporting post adjustably secured to said base.

5. A punch press as defined'in claim 1, in which said die holding bed is slidably connected to said forward pillars and has a die shoe supported upon it, and a die-clamping plate detachably secured on top of said die shoe to hold the dies in a fixed horizontal relation to said forward pillars.

6. The invention as defined in claim 1, in which said crank shaft has a fly wheel mounted intermediate its ends.

7. The invention as defined in claim 1, in which said cross member is detachably mounted on said pillars.

8. In a punch press, a base having a pair of upstanding spaced pillars secured thereto, a horizontal cross member rigidly. fixed upon opposite intermediate portions of said pillars, a slide having bearings disposed above and below said cross member and slidable on said pillars, a die bed having bearings disposed below said slide and slidable on said pillars, means on said cross member for operating said slide, means on said base for adjustably supporting asid die bed, and means in said slide and on said die bed for securing a punch and a die respectively.

EDWARD D. PERRY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS-

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