US2580078A

US2580078A - Press mechanism

Info

Publication number: US2580078A
Application number: US596271A
Authority: US
Inventors: Jr William C Denison
Original assignee: Denison Engineering Co
Current assignee: Denison Engineering Co
Priority date: 1945-05-28
Filing date: 1945-05-28
Publication date: 1951-12-25
Anticipated expiration: 1968-12-25

Description

W. C. DENISON, JR

Dec. 25, 1951 PRESS MECHANISM 2 SHEETS-SHEET 2 Filed May 28, 1945 FIG. 6.

IN V EN TOR.

WLUiam GDemson, Jr: BY

Z81 Z Y Patented Dec. 25, 1951 25ers PRESS MECHANISM William. C. Denison, Jr., Powell, Ohio, assignor to The Denison Engineering Company, Columbus, Ohio, a corporation of Ohio Application May 28, 1945, Serial No. 596,271

5 Claims.

This invention relates generally to machine tools and is particularly directed to tools employed in stamping, pressing and forming operations and classed as presses. The invention pertains to presses of the type utilizing frames having base and head sections joined by a back section, such frames being designated as 0 frames. Such presses have a ram guided for movement in either or both the head or base sections and means for operating the ram to cause it to exert pressing force against the other section or means held thereby. When such force is exerted, a re! action tends to cause the head and base sections to separate at their forward endswhere they are not directly connected while the, rear portions of these sections tend to move toward one another due to a pivoting action around the forward portion of the connecting back section. In the operation of such presses, the material of the frame at the forward portion of the back section is placed under tension, while the material at the :back portion is subjected to forces of compression. Between these portions is an indefinite line which is neither under tension or compression and which line is known as the neutral axis of the press frame. When the frame distorts in this manner, the axis of movement of the ram is forced out of alignment with the point on the base section with which it normally registers and consequently undue wear and possible breakage of punches, dies or other equipment used with the press results.

An object of this invention is to provide a C- shaped press frame with means on the opposite side of the neutral axis from the ram which will be operative to offset or counteract the compressive forces and thus reduce or eliminate the distortion and consequent misalignment mentioned above.

An ob ec of t e invent on. is to pro ide a p ess ha n a C-sha ed rame w th hydraulical y 0pt d p ess m ns t t e f nt th reof and means on the opposite side of the neutral axis of the frame responsive to the same fluid pressure used in the operation of the pressing means to impart an elongating force to the frame to counteract the tendency thereof to compress, thus at least partially eliminating the disadvanaees f prior frame .A urth r. o j ct o t i ention s to provide a press having a C-shap d f ame with ne or more-fl id r ivi hambers formed therewith such chambers having opposed surfacesand receiving fluid under pressure which exerts a force on the opp sed ac to mpartan l nga n or stretching effect to the frame whereby the compressive force resulting from the operation of the ram on the opposite side of the neutral axis of the frame will be counteracted.

It is a still further object of the invention to provide a press having a power cylinder on each side of the neutral axis, one of the power cylinders serving to operate the ram of the press by which useful work is performed, the other power cylinder exerting a force tending to separate the base and head sections of the press frame thus overcoming the compressive reaction resulting from the operation of the ram, the power cylinders being connected with thehydraulic system in such a manner that when the ram engages an article of work and the fluid pressure increases in the power cylinder therefor, the fluid pressure will also correspondingly increase in the other power cylinder.

Another object is to provide a press having a frame of the type mentioned in which the back section is initially bowed or shortened, the frame also having a power cylinder to apply straighten ing or lengthening forces to the frame and thereby counteract the tendency to compress or collapse when the ram is urged toward the work holder.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of embodiment of the invention is clearly shown.

In the drawings:

Fig. 1 is a side elevational view, partly in vertical section, of a press formed in accordance with the present invention;

Fig. 2 is a detail horizontal sectional view taken on the plane indicated by the line 11-11 of Fig. 1;

Fig. 3 is a side elevational view of a slightly modified form of theinvention; I

Fig. 4 is a similar view of a further modified form of the invention;

Fig. 5 is a side elevational view of a still further modified form of the invention;

Fig. 6 is a rear elevational view of the press shown in Fig. 5; and,

Fig. '7 is a detail horizontal sectional view taken on the plane indicated by the line VII-VII of Fig. 5.

Referring more particularly to the drawings and especially to Figs. 1 and 2, the numeral 26 designates a hydraulic press in which the features .of this invention have been. incorporated. The press 20 has a frame 2! which is of the usual C shape and includes a base section 22, a head section 23 and a back section 24 holding the other sections in vertically spaced relationship. The frame 2| may be cast in one piece from suitable material or it may be fabricated by welding sheet material of suitable gauge into an integral unit. The invention is applicable to presses having frames regardless of the manner in which power is transmitted to the press ram. For purposes of illustration, however, the invention has been applied to hydraulic presses for convenience in illustration and description.

The press 2|) is provided with a reservoir 25 for receiving the hydraulic fluid used in operating the press. Above the reservoir there is positioned a pump 25, the operating shaft of which is connected by a clutch 21 with the armature shaft 28 of an electric motor 30. The motor 30 in the present illustration, is attached to the side wall of the press frame as at 3|, the armature shaft of the motor being disposed in a vertical plane. When the motor is operated, the pump will be driven and will draw oil through the inlet pine 32 discharging such oil through an outlet pipe 33 to a relief valve 34, the latter being of conventional form and having a tank line 35 extending therefrom into the tank 25. A line 36 extends from the relief valve to the inlet of a four-way valve 3'! disposed in the head portion of the press frame .2|. The valve 3'! is provided with a pair of outlets which are connected by

lines

38 and 40 with the u per and lower ends, respectively, of a power cylinder 4|. The four-way valve 31 also has a discharge ort connected by line 42 with the reservoir 25 to complete the hydraulic circuit.

The power cylinder 4| is dis osed in a vertical position and is supported in the head section of the press frame over the opening in said frame. der into the opening, the ram 43 being mo able toward and away from the bottom section which is rovided with a bolster plate 44 in re ist ation with the ram. Both the ram and the bolster plate are ada ted to receive dies or other tools used in pressing, blanking, or forming opera-' tions. In the o eration of the press. the tool sections carried by the ram and the bolster plate must be accurately aligned, otherwise undue wear and possibly breakage will occur during use.

A collar 45 is secured to the lower portion of the ram and an arm 46 integrally formed with the collar projects rearwardly therefrom, the outer end of the arm having an opening to receive the shipper rod 4'! depending from the four-wa valve 31. Upper and lower collars 48 and 5| are secured to the shipper rod in spaced relation, the arm 45 alternately engaging these collars to eifect the operation of the four-way valve near the upper and lower ends of the strokes of the ram. The valve 3? may be of such type that when the ram engages an article disposed on the bolster and the pressure in the upper end of the power cylinder builds up to that for which the relief valve 34 has been set, the valve 31 will operate to direct fluid under pressure to the lower end of the power cylinder to cause the ram to return to its upper position. The valve 31 will also cause the ram to return to its starting position when the arm 46 engages the lower collar 50 on the shipper rod.

When, on each power stroke of the ram, the fluid pressure increases sufficiently to cause the operation of the relief valve 34, the ram will be A ram 43 projects from the power cvlinexerting a maximum downward force for which the relief valve has been set. When the ram exerts this force, there is a tendency for the upper or head and base sections of the 0 frame to spread or separate. Since the head and base sections are connected by the back section, this tendency results in a pivoting action around points indefinitely located near the upper and lower ends of the forward portion of the back section. This movement, although very slight, causes a strain at the forward portion of the back section and compressive forces at the rear portion of the back section. If this back sec tion is not constructed of sufficiently heavy material and properly reinforced, fatigue of the metal may take place with consequent failure of the press frame. This movement of the head and base sections relative to the back section also causes a misalignment of the tool sections mounted on the bolster plate and ram. If sufiicient movement takes place the misalignment may cause severe wear or breakage of the tool sections. The press shown in Figs. 1 and 2 has been designed to counteract the tendency of the upper and lower sections to move when the ram exerts a pressure against the bolster plate.

To counteract this tendency it is proposed to exert a separating or spreading force on the head and base sections at the rear of the back sec tion; that is, at the opposite side relative to the ram 43 of the points where these sections tend to pivot on the back section. To this end the press frame 2| has fluid receiving cylinders 5| integrally formed with the back section at the rear thereof. These cylinders 5| have oppositely directed surfaces 52 at the ends thereof which surfaces are parts of the end walls of the cylinders 5|. Suitable braces 53 are provided to transmit force applied to the surfaces 52 to the head and base sections. Fluid is conducted to the cylinders 5| through pipes 54 which are connected with the upper end of the power cylinder 4|. The cylinders 5| are normally full of the hydraulic fluid and when the ram 43 engages the work on the bolster plate, fluid pressure will be built up in the upper end of the power cylinder 4| in theconventional manner. This fluid pressure will be transmitted through pipes 54 to the cylinders 5|, the fluid exerting a force on the surfaces 52. This force tends to separate the surfaces 52 thus causing an elongation of the back section at its rear portion. This tendency to elongate counteracts the tendency to compress caused by the operation of the power cylinder 4|. Since the power cylinders 5| are connected with the power cylinder 4| by the line '54, force will only be applied to the faces 52 when the power cylinder 4| is in operation. It will also be noted that since the cylinders 4| and 5| are directly connected, the pressure will increase in all at the same time and at the same rate. It will of course be necessary to compute rather accurately the required areas of the surfaces 52 as well as their location from the neutral axis of the frame 2| relative to that of the power cylinder so that the correct amount of force and elongation will be produced. Such computations are of course within the skill of press engineers- It should be obvious from the foregoing that the cylinders 5| may be integrally formed with the press frame as shown in Figs. 1 and 2 or separately formed and attached to the frame in any suitable manner.

It will be noted from an inspection of Fig. 1 that the cylinders 5| have no movin parts. In

the elongation of the frame between the end surfaces 52 forcounteracting the compressive force. It is also possible-to employ a power cylinder with movable piston for performing the same elongating result. Presses equipped with such a cylinder are illustrated in Figs. 3 and 4.

In Fig; 3 the press frame is an integral device formed either by casting or welding as in the press shown in Fig. l, but the frame 5:: has a recess at the rear of the back section. This recess reduces the effective size of the back section by the omission of material which would be under compression during the operation of the ram 55. The frame 55 would be relatively weak at the narrowest portion of the back section and stresses due to the operation of the ram would be more; or less concentrated at this region. To prevent the frame from bending when the ram 56 is operated, a power cylinder 5'! is disposed in the recess 58, the body of the power cylinder being mounted on the base section as at fill and the ram being secured as at 6| to the top section. Fluid is supplied to the power cylinder through an inlet pipe 62 which extends to the lower portion of the cylinder 5'5. As indicated by dotted lines, the piston in the power cylinder 51 extends normally to the lower end so that in the event no fluid under pressure is supplied to the power cylinder, the inter-engagement of the piston with the lower end of the cylinder will tend to prevent the movement of the top and bottom sections toward one another at the rear portion. By supplying fluid under pressure to the cylinder 51 when the ram 56 is operated in the same manner as in the form first described, the power cylinder '51 will exert force on the top and the bottom sections and tend to separate the same. This force will oppose the reaction resulting from the operation ofthe ram 5'6 and the back section of the frame 55 will be prevented from bending. In Fig. 3, the neutral axis of the press frame 55 is indicated generally by a dotted line 63. This axis varies depending upon the dimensions and shape of the back section In Fig. 4, the press 64 has separate head and base sections 65 and 66 which are connected by an upright member 61. The sections 65 and 6E may be either pivotally or rigidly attached to the upright. At the rear of the upright 67, the press 64 is provided with a power cylinder 68 which is similar in form and operation to the cylinder 5! in the form of the invention shown in Fig. 3. The cylinder 68 includes the ram lil which normally engages the bottom wall of the cylinder 68. If desired, suitable means such as the spring H may be employed to yieldably urge the rear ends of the head and base sections toward one another, the movement being limited by the engagement of the ram ill with the inner end of the cylinder 68. When fluid is supplied to the ram 12 to move it toward the work positioned on the bolster plate 13, fluid will also be applied through pipe 14 to the lower end of the cylinder 68. No fluid will flow through the pipe Hi however until the resistance offered to fluid flow by the ram 12 equals that, offered by the ram iii. At this time the pressure on the fluid will build up until it reaches that for which the relief valve of the hydraulic system has previously been set at which time such pressure will exist in the power cylinder at the front of the ram as well as the one at the back thereof. In both forms of the invention shown in Figs. 3 and, 4, the sizes of the

power cylinders

51 and 68 and their distan'ces from the neutral axis 'of' the press frame will necessarily be such as to deliver substantially-equal forces to those delivered by the rams 55 and 12. The press frames will thereby be prevented from distorting a distance'suificient to prevent the proper alignment of the die sections which are mounted on the ram and the bolster plate.

In Figs. 5, 6, and '7 'a press frame having a partially collapsed back section has been illustrated. As shown in Fig. '7, the back section is substantially U-shaped in horizontal cross section, each leg of which is provided with a vertically extending slot 18 to form a back section '59 and auxiliary strip-like members 80. The sides of themember 19 are depressed as at 82 to slightly increase the length of the material making up the section and'permit a limited degree of extensio'nthereof. The members are also depressed for the same purposeand a power cylinder 83 extends between the central portions of these members. The power cylinder 83 includes a body 84 and a piston section 85, the inner end of the latter normally engaging the inner end wall of the former. A pipe line 86 connects the inner portion of the body 84 with a suitable source of fluid such as the system shown in Fig. 1. When the fluid in the cylinder 84 is exposed to pressure from the system, there will be a tendency for the piston 35 to be forced outwardly in the cylinder 84 thus increasing the effective length of the power cylinder 83. This movement will be transmitted to the members 80 and since these members are attached at their upper and lower ends to the head and base sections of the press frame 15 there will be a tendency for these members to increase in length also, thus increasing the space between the base and head sections. By connecting the power cylinder 83 through the pipe 86 p with the upper end of the power cylinder 81 at the forward portion of the frame 15, the power cylinder 83 will be supplied with pressure at the same time as the power cylinder 81. Since this pressure is built up only when the ram is exerting force on an object positioned on the bolster plate, a separating force will be applied to the front and rear portions of the base and head sections simultaneously, thus preventing any tipping or pivoting action thereof.

It should be obvious from the foregoing that the elongating force necessary to counteract the collapsing or compressing tendency of the frame may be applied in a number of diiferent ways, the form selected for illustration being by way of example only and not intended as a limitation of the invention.

While the form of embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

I claim:

1. In a press, in combination, a C-frame with base and head sections integrally united by a back section having spaced side walls; a hydraulically operable cylinder-piston assembly supported by said frame; and fluid pressure responsive movable elements operative to apply oppositely directed forces to said side walls at points of joinder thereof with said base and head sections, said forces tending to increase the effective length of said side walls.

2. In a press, in combination, a C-frame with base and head sections united by a back section having spaced side walls with converging portions and means for applying forces tending to separate said converging portions to increase the efiective length of said walls and increase the distance between the base and head sections.

3. In a press, in combination, a O-frame with base and head sections united by a back section having spaced side walls with longitudinally extending slots, the portions of said walls on the opposite side of said slot from the throat of said frame being shaped to decrease their effective length; and means connected with said walls and operative to increase their efiective length.

4. In a press, in combination, a C-frame with base and head sections united by a back section having spaced side walls with longitudinally extending slots, the portions of said walls on the opposite side of said slot from the throat of said frame converging toward the intermediate regions thereof; and power means between the converging regions of said walls, said power means being operative to force'said walls to separate to increase the effective length thereof.

5. In a press, in combination, a C-frame having base and head sections connected by a back section; side walls forming parts of said back section, said side walls having actual lengths in excess of their eflective length; and a fluid pressure responsive device operative simultaneously with said press to increase the effective lengths of said side walls.

WILLIAM C. DENISON, JR.

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

UNITED STATES PATENTS Name Date