US2007290A

US2007290A - Power press

Info

Publication number: US2007290A
Application number: US731448A
Authority: US
Inventors: Ross B Treer
Original assignee: Cleveland Punch & Shear Works
Current assignee: Cleveland Punch & Shear Works; Cleveland Punch & Shear Works Co
Priority date: 1934-06-20
Filing date: 1934-06-20
Publication date: 1935-07-09
Anticipated expiration: 1952-07-09

Description

R. B. TREER July 9, 1935.

POWER PRESS Filed June 20, 1934 5 Sheets-Sheet 1 ATTORNEY.

July 9, 1935. R. B. TREER 2,007,290

POWER PRESS Filed June 20, 1954 5 Sheets-Sheet 2 6 3+ 32 8 1 O /7-- O a r 42 I (Y i INVENTOR. J g- BY [3m M W (5 W ATTORNEY.

July 9, 1935; R. B. TREER 2,007,290

POWER PRES S 0% NY a a $1 a i MM"; i

x Q1 s UMIQ/MW ATTORNEY.

July 9, 1935. R. B. TREER 2,007,290

POWER PRESS Filed June 20, 1934 5 Sheets-Sheet 4 INVENTOR. v BY B ATTORNEY.

July 9, 1935. R. a. TREER 2,007,290

POWER PRES S Filed June 20, 1934 5 Sheets-Sheet 5 jgfgj BY QMBQMW ATTORNEY.

Patented July 9, 193 5 UNITED STATES PATENT OFFICE POWER PRESS Application June 20, 1934, Serial No. 731,448

14 Claims.

This invention relates to power presses, and has for its principal object to provide means whereby its various parts cannot be subjected to more than a certain predetermined pressure thus eliminating all possibility of breaking or injuring any of the various parts, whenever an abnormal resistance is met with, caused for instance by the excessive thickness or hardness of the stock being worked on.

Another object of the invention is to provide a die cushion for presses of this type, which is normally held against a stop by a predetermined pressure, but which will move away from this stop when acted on by a counter pressure greater than the predetermined pressure holding it against the stop.

Another object of the invention is the provision of a simple valveless mechanism through which a relatively small cylinder and piston, acted on by a relatively low pneumatic pressure, will cause a high pressure to be exerted against a die or die support, mounted in a power press.

Another object is the provision of a die cushion and means for adjusting its position with respect to the press, thereby to make it possible to easily, quickly and accurately accommodate the press to various types of work.

A further object is to provide a device of this character which may all be contained within the base of the press.

A still further object is to provide a device of this character which is very eflicient in operation, but which is simple of construction and easily installed in existing presses, and is applicable to any of the various types of power presses now in general use.

In the accompanying drawings which show two forms of my invention as applied to one type of press, Fig. 1 is a front elevation of a power press with my improved cushioning means incorporated therein; Fig. 2 is an enlarged se'ctional view through the base of the press showing one form of my invention; Fig. 3 is a horizontal section taken on the line 33 of Fig. 2; Fig. 4 is a bottom plan view showing the low pressure cylinder in section; Fig. 5 is a view similar to Fig. 2 of another form of my invention and Fig. 6 is a view similar to Fig. 4 of the form shown in Fig. 5.

Referring to the drawings by reference characters, I indicates the base of a power press; 2 and 3, a pair of side frames extending upwardly from the base and 4 the crown which connects the upper ends of the side frames. A die cushioning mechanism generally indicated at 5 is secured in the base of the press by a ring 6. The base I,

side frames

2 and 3, crown 4 and ring 6 are clamped tightly together by the rods 1 and nuts 8.

A plunger 9 is slidably mounted between the

side frames

2 and 3 and is held by gibs ID. This plunger is reciprocated through a connecting rod l I by a crankshaft l2, which in turn is driven through a gear l3 by any suitable means. A clutch mechanism for controlling the operation of the press is indicated at l4.

The die cushioning mechanism 5 will now be described. A cylinder I5 having its upper end internally threaded as indicated at 2| has its outer diameter reduced at its upper and lower ends, as indicated at I6 and I1, forming peripheral shoulders I8 and I9. The reduced upper end I6 is inserted in an opening 20 in the top of the base with the shoulder l8 engaging the underside of the top of the base. The ring 6 surrounds the reduced lower end ll of the cylinder and engages the shoulder I9. Thus, when the nuts 8 on the tie rods I are tightened, the cylinder will be rigidly secured in the base of the press, as is clearly shown in Fig. 2. A cap I5 closes the lower end of the cylinder I5.

A second cylinder 22, exteriorly threaded at 23, is screwed into the interiorly threaded upper end of the cylinder l5. Slidably mounted in the cylinder 22, is a piston 24, which has a reduced part 25 extending out through the head 26 of the cylinder. A shoulder 21 is formed at the junction of the reduced part 25 of the piston, with the body portion 24. In the normal operation of the press, the piston is held in the position shown in Fig. 2, with the shoulder 21 engaging the head of the cylinder, which acts as a stop to limit the upward movement of the piston.

The other end of the cylinder 22 is closed by a cap 28 which has a spur gear 29 formed on the periphery thereof.

A die slide 30, slidably mounted between the

side frames

2 and 3 by gibs 3 I, is supported by the outer reduced end 25 of the piston 24. A die A is fastened to the die slide 30, in alignment with a complementary die B, carried by the plunger 9. C indicates the stock being formed between the dies A and B when they are brought together by the downward movement of the plunger 9.

Slidably mounted in the cylinder l5, between the cap l5 and the lower end of the cylinder 22, is a piston 32, which has an upwardly extending circular plunger 33 secured thereto by a nut 34. This plunger 33 extends through an opening in the cap 28, and into the cylinder 22. The piston 24 is recessed at- 24 to permit the plunger 33 to extend upwardly a considerable distance into the cylinder 22, and to provide a greater space between the piston 24 and the plunger 33, which is completely filled with a suitable fluid, preferably oil, designated by the numeral 35.

A gear 36, keyed onto a shaft 31, which is journaled in bosses 38 on the cylinder l5, extends through an opening 39 in the side of the cylinder l5 and meshes with the gear 29 on the cap 28, secured to the lower end of the cylinder 22. R0- tation of the gear 36, by hand or any suitable power means (not shown), will move the cylinder 22 upwardly or downwardly in the threads 2|. This in turn will move the piston 24 and die slide 30 and die A supported thereby in a like manner. Thus it is possible to easily, quickly and accurately adjust the position of the lower die A with respect to the press and the upper die B, to accommodate the press to various types of work.

Air is supplied under pressure to the cylinder 45, between the cap 15 and piston 33 from a tank or compressor 40 through a pipe 4| and opening 42 in the cap I5 A pressure regulator or checkvalve 43 will maintain a predetermined pressure of air in the cylinder l5. This air in the cylinder l5 will hold the piston 32 and plunger 33 up in the positions shown in Fig. 2 until the plunger 33 is acted on by a downward force in excess of the total force acting upwardly on the piston 32. The plunger 33 and piston 32 will then move downwardly until the two forces equalize, or until the pressure on plunger 33 is reduced.

The fluid 35 is forced into the cylinder 22, and the air bled out therefrom, through a pipe 44 and opening 45 near the upper end of the piston 24. After the space in the cylinder 22 has been completely filled with fluid, and a desired predetermined pressure on the fluid has been reached, a valve 46 in the pipe 44 is closedto retain the fluid in the cylinder under the desired predetermined pressure. A gauge 41 indicates the pressure in the cylinder 22.

The bores of the cylinders l5 and 22 and consequently the diameters of the

pistons

24 and 32, and the diameter of the plunger 33, all bear a direct relation to each other and are determined by the total force to be exerted on the work, and the air pressure in the cylinder IS.

The die cushions illustrated herein are designed to permit a total maximum force of 252,000 pounds on the work C, with an air pressure of -78 pounds per square inch in the cylinder [5. The internal diameter of the cylinder 22 is 10 inches and the area of the piston 24 is 78.54 square inches. The internal diameter of the cylinder I5 is 16 inches and the area of the piston 32 is 201.06 square inches. The diameter of the plunger 33 is 2.5 inches and the area of its upper end is 4.9 square inches. The fluid 35 is placed in the cylinder 22 under a pressure of 3208 pounds per square inch. This will exert a total upward pressure of 252,000 pounds on the piston 24, and a total downward pressure of 15,719 pounds on the piston 32, and the plunger 33.

From the foregoing, it will be seen that all of the various parts will remain.stationary in the positions shown in Fig. 2, until the plunger 9 exerts a total downward pressure in excess of 252,000 pounds thereon. Whenever this occurs, due to excessive thickness or hardness of the stock being worked on, or for any other reason, the piston 24 will be moved downwardly until the plunger 9 has reached the limit of its downward stroke. This downward movement of the piston 24, will be transmitted through the fluid 35 to the plunger 33 and piston 32 and cause them to move downwardly against the air pressure in the cylinder I5. Due to the difference in diameter of the piston 24 and plunger 33, the plunger 33 and piston 32 will move a great deal faster and farther than the piston 24. In the particular apparatus illustrated, the ratio between the piston 24 and the plunger 33 and consequently the piston 32 is 16 to 1.

This arrangement of the various mechanisms, makes it impossible to exert more than a certain predetermined pressure on any part of the press and thus eliminates all possibility of breaking or injuring any of the various parts by excessive pressures.

This arrangement of the various parts, and the pre-loading of the cylinder 22 with fluid under high pressure, prevents any movement, however small, of the die A unless a defective piece of stock is being worked on. This results in a much more uniform and higher grade of forgings.

In the form illustrated in Figs. 5 and 6, the parts that are common to the form shown in Figs. 1 to 4 are indicated by the same reference characters. In this form, the cylinders l5 and 22 are formed in one piece with a partition 50 dividing them, and are secured in the base I by means of lugs 5| on the cylinder l5 through which the tie rods 1 pass. The upward movement of the piston 24 is limited, and the position of the die A is adjusted by means of a ring 52 that is screwed into the upper end of the cylinders 22 as indicated at 53. The filling pipe 44 through which oil is forced into the cylinder 22 is screwed directly into the cylinder 22 as indicated at 55.

From the foregoing description of the drawings forming part of this application, it will readily be seen that I have provided simple and efficient mechanism for effectively accomplishing the objects of the invention.

Having thus described my invention, what I claim is:

1. In a device of the character described, the combination of a movable die support, a stop, means for normally holding the die support against said stop with a predetermined high pressure, said means comprising a relatively small cylinder, a piston in said cylinder, a relatively low pneumatic pressure in said cylinder acting against said piston, a fluid interposed between the die support and the piston, a container for said fluid, and mechanism for maintaining the volume and pressure of said fluid in said container con stant under all conditions of operation.

2. In a device of the character described, the combination of a cylinder, a piston in said cylinder, a die secured to the outer end of said piston, means for exerting a predetermined pressure against the inner end of said piston, said means comprising a fluid in said cylinder, and means for maintaining a volume of fluid and the pressure on said fluid constant for all positions of said piston, said second mentioned means comprising a movable plunger of lesser diameter than the diameter of the piston, extending into said cylinder and means for maintaining a predetermined pressure against the outer end of said plunger.

3. In a device of the character described, the combination of a cylinder, a piston slidably mounted in said cylinder and extending out of said cylinder, a die mounted on the outer end of said piston, a second cylinder of larger diameter than the first cylinder, a piston in said second cylinder, a plunger secured to said second mentioned piston .andextending into said first mentioned cylinder, a fluid in said first mentioned cylinder completely filling the space between the first mentioned piston and said plunger, and

means for maintaining a substantially constant predetermined pressure in said second cylinder.

4. In a device of the character described, the combination of a base, a cylinder mounted in said base, a piston slidably mounted in said cylinder and having one end extending out of said cylinder, a die mounted on the outer end of said piston, means for adjusting .the position of said piston with respect to said base, a second cylinder of larger diameter than the first cylinder, a piston in said second cylinder, a plunger secured to said second mentioned piston and extending into' said first mentioned cylinder, a fluid in said first mentioned cylinder completely filling the space between the first mentioned piston and said plunger, and means for maintaining a substantially constant predetermined pressure in said second cylinder.

5. In a press of the character described, the combination of a cylinder mounted in the base thereof, a piston in said cylinder, a stop limiting the movement of the piston in one direction, a die secured to the outer end oi the piston, a second cylinder of larger diameter than the first cylinder, a piston in said second cylinder, a plunger of smaller diameter than said first mentioned piston secured to said second mentioned piston and movable therewith and extending into said first mentioned cylinder, a fluid in said first mentioned cylinder interposed between said first mentioned piston and said plunger, and means for maintaining a substantially constant pneumatic pressure against said second mentioned piston.

6. In a. device of the character described, the,

combination of a movable die support, a stop, means for normally holding the die supportagainst said stop with a predetermined high pressure, said means comprising a relatively small cylinder, a piston in said cylinder, a relatively low pneumatic pressure in said cylinder acting' against said piston, a fluid interposed between the die support and the. piston, a container for said fluid, and mechanism for maintaining the volume and pressure of said fiuid in said container constant under all conditions of operation, and

means for adjusting the position oi said stop.

"I. In a die cushion ior presses of the character described, the combination of a base, an internally threaded opening in said base, an externally threaded cylinderscrewed into said opening, apiston in said cylinder, a die supported by the outer end of said piston, means for exerting a pressure against the inner end of said piston,

' and meansfor adjusting the position of said cylform pressure against the inner end of said piston, and means for adjusting the position ofthe second mentioned cylinder within the first mentioned cylinder.

9. In a device of the character described, the combination of a base, a cylinder internally threaded at-one end, mounted in said base, a sec- .ond cylinder, externally threaded, screwed into said first mentioned cylinder, a piston in said second mentioned cylinder, a die supported by the outer end of said piston, cooperating means in said cylinders for maintaining a substantially uniform pressure against the inner end of said piston, and means for adjusting the position of the second mentioned cylinder within the first mentioned cylinder, said means including a pair of gears, one of said gears being secured to said second mentioned cylinder.

.cluding a ring threaded into the outer end of .said cylinder and engaging the shoulder on said piston.

11. In a device of the character described, the 36 combination of a base, a pair of side frames, a crown, a die cushion mounted in the base, said die cushion including a cylinder, a shoulder on the periphery of said cylinder, a ring surrounding said cylinder and engaging said shoulder, a

plurality of tie rods extending through said ring,

base, side frames and crown thereby to clamp them all tightly together, a plunger slidably mounted between said side frames and means for reciprocating said plunger.

. 12. In a device oi! the character described, the combination of a base, a pair of cylinders of difierent diameters, the smalleroi said cylinders means including a shoulder on the periphery of said larger cylinder, a ring surrounding said larger cylinder and changing said shoulder and bolts securing said ring to said base.

13. In a device of the character described, the combination of a base, a cylinder mounted in said base, a piston slidably mounted in said cylinder, a fixed volume of fluid in said cylinder beneath said piston a die supported by the outer end of said piston, a second cylinder, and cooperating means in said cylinders for always maintaining the volume of fluid in said cylinder and the pressure thereon constant for all positions of said piston.

14. In a device of the character described, the combination 0! a base, a cylinder mounted in said base, a piston slidably mounted in said cylinder, a stop for limiting the movement of said piston in one direction. a die supported by the outer end of said piston, a second cylinder, and coopperating means in said cylinders for always exerting a certain predetermined pressure against the inner end of said piston and for normally. holding said piston in engagement with said stop.

R088 3. mm.