US3362322A - Press - Google Patents

Description

Jan 9, 1968 w. G. MOEHLENPAH 3,362,322

PRESS Filed July 20, 1966 vII 3?) F|G.l. 33 37 FIG.2.

United States Patent M0., assignor to Hydro- Louis, Mo., a corporation of This invention relates to presses and, more particularly, to C-shape hydraulic presses.

Among the several objects of the invention may be noted the provision of an improved press construction which is highly efiicient, said press being capable of doing a given pressing job with less pressure than prior press constructions or, alternatively, being capable of accomplishing more work at a given pressure; the provision of an improved construction for a C-shape hydraulic press wherein high efliciency is achieved by utilizing the tendency of such presses to open-up when they exert high pressure against substantially parallel faces of work; the provision of a C-shape press capable of exerting a substantially uniform force on all parts of two parallel faces of work during pressing operations; the provision of a C-sh-ape press particularly suitable for driving connector plates int-o wood truss members so that the plates are flush with the truss members and all of the teeth of the plate are completely driven into the truss member, thereby avoiding a gap between one side of the plates and the truss members and avoiding crushing of the truss members at the other side of the plates; and the provision of such a press which is lighter in weight and less expensive than comparable presses. Other objects and features will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the constructions hereinafter described, the scope of the invention being in dicated in the following claims.

In the accompanying drawings, in which one of various possible embodiments of the invention is illustrated.

FIG. 1 is a view, partially in elevation and partially in section, of a press of this invention; and

FIG. 2 is a fragmentary elevation showing the press platens after they have driven teeth struck from connector plates into wood truss members.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Referring to the drawings, a press of this invention generally comprises a press body .1 of substantially C-shape configuration which carries an upper platen 3 and a lower platen 5. 'Platen 3 has a flat surface 3a and platen 5 has a flat surface 5a. The centers of platen surfaces 3a and 5a are aligned along an axis designated 7. lPlaten 3 is moved toward and away from platen 5 by operation of power means generally designated 9 with platen 3 being moved along an 'axis 11 which is offset from the axis 7 passing through the centers of the platen surfaces. Preferably platen surfaces 3a and 5a are slightly nonparallel to each other as shown in FIG. 1 prior to the application of a compressive force to the work and they are adapted to assume a substantially parallel relation to each other as shown in FIG. 2 when a sufliciently large compressive force is exerted on generally parallel faces of a piece of work by operation of power means 9. The work comprises nailing plates N1, N2 and abutting wood members W of a truss into which teeth T of the plates are to be driven.

More particularly, the press body 1 comprises a base portion "13 and two spaced generally parallel arms 15 and 17 projecting from opposite ends of the base. The body 1 may be constructed from a pair of C-shape side plates one of which is shown at 19, said plates being fixed in spaced relation by attachment to inner and outer end plates 21 and 23, respectively. A runner or guide 25 may be provided at the bottom of the press body for guiding the press into apparatus holding the work. Platen 5 is fixed ,to the outer end portion of arm 17 of the press body by welding bracing plates or gussets 27 to the plates 19 and to the bottom of the platen.

The power means 9 comprises an elongate hydraulic cylinder 31 which is welded to the outer end portion of arm 15 of the press body. An end plate or head 33 closes the upper end of the cylinder and the lower or rod end of the cylinder is substantially open.

Hydraulic fluid may be introduced into the head end of the cylinder through a port 35 in head 33. A nipple 37 threaded into the port is connected to a hydraulic line 39 through which hydraulic fluid under pressure from a suitable source (not shown) can be introduced into and removed from the cylinder. Another port 41 between the ends of the cylinder is in communication with the source of hydraulic fluid which when introduced under pressure into the cylinder moves the ram upwardly in the cylinder. The central axis of the bore of cylinder 31 is aligned with axis 11. The cylinder is mounted on the body in such a manner that the open end of the cylinder faces platen 5 and axis 11 passes through the platens in space relation of the centers of the platens. That is, axis 11 is further from base 13 of the press body than is the axis 7.

An elongate ram 43 has one end portion positioned within cylinder 31 and another end portion projecting from the rod or open end of the cylinder. Platen 3 is fixed to the projecting end of the ram and may be braced on the ram by suitable plates or gussets 45. Ram 43 comprises a tube 47 which has an outside diameter only slightly smaller than the inside diameter of cylinder 31. Tube 47 is closed to the passage of hydraulic fluid by a plate or head 49 extending across the tube. Head 49 is spaced from the upper end of tube 47 so that there is a small space 51 at the inner end of the ram into which hydraulic fluid can be forced through port 35 in the cylinder.

A pair of annular bushings 53 on the inner end of the ram are positioned on opposite sides of a packing ring 55. The bushings and rings are fixed to the ram for movement therewith by a pair of snap rings 57 seated in grooves on the outer surface of tube 47 adjacent bushings 53. Packing 55 is compressed by bushings 53 and prevents passage of hydraulic fluid around the packing. The bushings and packing slide along the inner surface of the cylinder during operation of the power means.

Two additional annular bushings 59 and a packing ring 61 are provided at the lower or open end of cylinder 31. The bushings 59 and packing 61 are held in place by a snap ring 63 seated in a groove in the inner surface of the cylinder and by a retainer ring 65 which screws into the lower end of the cylinder and bears against the lower bushing 59 to compress packing ring 61. Ram 43 engages and slides within bushings 59 and packing 61 as the ram reciprocates in the cylinder. Packing 61 seals this sliding connection between the cylinder and ram to prevent loss of hydraulic fluid from the cylinder.

It will be observed that the bushing 59 is spaced a short distance from the fluid port 41 in the side of the cylinder. The annular space 67 formed between the bushings and packings on the cylinder and on the ram communicates with port 41. Lower bushing 53 and packing ring 55 form a piston on the upper end of ram 43 so that hydraulic fluid introduced into space 67 through port 41 bears against the lower one of the bushings 53 and against the packing 55 to urge the ram into the cylinder to its fully retracted position shown in the solid line position of FIG. 1. When hydraulic fiuid is introduced through port 35 into space 51 3 it acts against the head 49 of the ram, against the upper end of tube 47, and against the upper one of the bushings 53 and the packing 55 to urge the ram downwardly out of the cylinder to its extended position. As the ram has an outside diameter which is only slightly smaller than the inside diameter of the cylinder, and as the lower end of the ram is directly secured to the upper surface of platen 3, a sturdy interconnection between the ram and platen results. Also, because the rams outside diameter is only slightly smaller than the cylinders inside diameter, very little fluid needs to be introduced into space 67 in order to raise the ram and therefore the ram may be easily retracted at a faster rate than that at which it is extended.

Platens 3 and are preferably generally rectangular in A shape and the same size. The platens have heels or edges 3b and 5b near the press throat, i.e., near the base portion 13 of the press body. The platen surfaces 3a, 5a at edges 3b, 5b are spaced apart a distance somewhat greater than the spacing between the surfaces at the opposite edges and 5c of the platen. This difference in spacing is somewhat exaggerated for purposes of illustration in the drawings. By way of example, a 25 ton capacity press may have the surface 5:: at edge 50 about to /8 higher than at the edge 5b. This locates the platen surfaces at edges 3b and 5b about /8" to A further apart than edges 3c and 5c. Thus platen surfaces 3a and 5a are nonparallel to each other prior to the application of a cornpressing force to the work. The body 1 and other parts of the press will flex to some extent under pressing forces in spite of the rugged construction of the press. Because of this and the fact that the axes 11 and 7 are offset from each other, the platen surfaces 3a and 5a become substantially parallel to each other as shown in FIG. 2 of the drawings when a sufliciently large compressive force is exerted on generally parallel faces of the work by operation of the hydraulic apparatus.

Operation of the hydraulic press will now be described.

The description of the operation of the press will illustrate its use for driving a pair of nailing or connector plates N1, N2 into two pieces of wood W during manufacture of a truss. However it will be understood that a press of this invention can be used for substantially any pressing operation where the faces of the work are to be maintained parallel as heavy compression forces are applied. The connector plates conventionally have teeth T struck from them. The lower connector plate N2 and the wood truss members may be positioned on suitable truss building apparatus, such as the apparatus shown and described in US. Patents No. 3,068,484 and 3,069,684. This apparatus includes a vertically movable locator tray or plate P on which the lower connector plate N2 rests. The upper connector plate is positioned above and bridges abutting edges of wood truss members.

When the plates and wood members are properly located the upper and lower surfaces of the plates are substantially parallel to each other. The press is moved to a position where the upper platen 3a overlies the nailing plate N1 and the lower platen 5 is beneath the locator plate P and the lower platen N2. Then hydraulic apparatus associated with the press is operated so that hydraulic fluid under pressure is delivered through the line 39 and port into the space 51 at the top of the ram and cylinder and simultaneously the line communicating with port 41 is opened so that hydraulic fluid in annular space 67 can be forced from the space. As the hydraulic fluid under pressure enters space 51 it acts against the inner surface of head 49 to start extension of the ram and then after the end of the tube 47 moves away from head 33 the fluid also simultaneously acts against the end of the tube 47 and the upper bushing 53 and packing 55. This extends the ram 43 and moves platen 3 downwardly toward platen 5 to press the connector plates until the teeth are completely driven into the wood truss members and the plates are flush with the truss members. During this operation the press tends to open up at its mouth so that the platen surfaces change from their nonparallel relation when unloaded to a generally parallel relation when loaded.

Briefly, the theory of operation of a press of the invention is that the displacement of the axes 7, 11 causes a controlled flexing of the platens which substantially counterbalances the normal opening of a C-shape press at its mouth as it is loaded.

There are principally two structural features of the press which cause the facing surfaces of the platens to become parallel when heavily loaded, i.e., (1) the ram axis 11 is offset away from the throat of the press relative to the axis 7 through the centers of the platen surfaces, and (2) the platen surfaces are preferably initially nonparallel, the greatest separation being at the heel of the platens in the throat of the press. (A discussion of operation when the platens are initially parallel will be discussed later.) To fully understand operation of the press there are two other features inherent in a C-shape press which must also be considered, i.e., (1) that a C-shape press tends to open up at the mouth of the press (edges 30, 5c of the platens) as the press is loaded and (2) that even though the platens are rigidly mounted some flexing or springing of the platens may occur relative to their mountings. The press as a whole tends to flex about a pivot point located in the base portion 13 of the frame and the platens tend to flex about the axis 11 of the ram. In ordinary presses the ram axis and the centers of the platens are aligned with each other and with the center of the work piece to avoid any flexing of the platens (separate from the opening of the press), but when the platen and ram axes are offset and the press load is offset from the ram axis, then the various load forces acting on the platens, when averaged, determine a central point spaced from the ram axis from which these forces appear to act on the work. This location of this point determines which direction the platens flex. The distance between this point and the ram axis constitutes a moment arm, and the length of the moment arm multiplied by the force applied at this point determines the force tending to flex or spring the platens. The manner in which these principles affect operation of the press of the invention will now be described.

It will be assumed initially that the work piece has parallel surfaces substantially the same size and shape as the platen surfaces 3a, 5a so that the force exerted by the ram is equally distributed substantially throughout the entire surface of each platen. Because the axes 7 and 11 are offset and axis 7 is nearer the heel edges 3b, 5b of the platen, the length of the moment arm between ram axis 11 and the heel edges 3b, 5b is greater than the length of the moment arm between the ram axis and platen edges 30, 5c at the mouth of the platen. For this particular situation, the various forces acting on the platens about these moment arms are centralized at a point at the center of the platens, that is on the axis 7. Thus for this situation the total forces tending to flex or spring the platens can be determined by multiplying the total force acting on the platens by the length of the moment arm (the distance between axes 7 and'll). Since axis 7 is nearer heels 3!), 511 these forces tend to open the platensat the heels.

At this point it may be noted that this opening of the platens at the heels is also facilitated by the press construction. Features which encourage this opening or flexing include the heel portion of platen 3 being cantilevered more than its mouth portion relative to cylinder 31, and the fact F that the gusset 45 bracing the platens heel edge 3b is inclined at a more acute angle (relative to the horizontal) than that of the gusset 45 bracing the platens mouth edge 30. Also, the platens are somewhat thinner at the heel edges than at the mouth edges.

As the pressure exerted by the ram increases, the edges 3c, 5c of the platen at the mouth of the press tend to open relative to the heel edges due to the normal deflection of the press about the yoke or center portion 13 of the press body. This opening of the mouth of the press tends to counterbalance the effect of the offset axes, which as noted above, tends to move the platens apart at the heels as ram pressures increase. Thus these compensating effects operate to substantially maintain the platens in their initial (unloaded) relation as the ram pressures increase and the platens move together. However, the amount the platens will flex in their mounting is limited so that at very high press loads the amount the press opens at its mouth (due to flexing of the press body) usually exceeds the compensating flexing or springing of the platens in the opposite direction. Therefore, where there will be operation at very high ram pressures the platen surfaces 3a, 5a are preferably made initially nonparallel to each other with the surfaces being closer together at the mouth of the press as shown in the drawings. Therefore the platens will continue to remain substantially parallel from low ram pressures up through the maximum load.

The foregoing description has been based on the assumption that the work piece is substantially the same size and shape as the platens. When the work pieces are substantially smaller than the platen surfaces, then they are preferably centered in the press near the ram axis 11 since, for small nailing plates, the teeth become fully driven in the truss members at lower pressures and the canted platen surfaces become generally parallel at lower pressures when the work is displaced away from axis 7 toward the mouth of the press.

In prior press constructions in which the facing platen surfaces are parallel prior to being loaded and become nonparallel when loaded, the teeth at the inner or right side of the nailing plates are frequently fully driven into the wood members whereas the teeth at the left edges or sides of the plates are less than fully driven into the truss members or, if the teeth at the left side of the plates are fully driven into the wood, then the wood is crushed beneath the right side of the plates and the teeth tend to withdraw from the crushed part of the wood. In either case the strength of the joint being formed is reduced. When using prior art presses the teeth at the left edge or open side of the press can be fully driven only by exerting unusually large compressive forces on the plates. For this reason the capacity of presses previously used for building trusses are frequently very high. With the press of the invention, on the other hand, the plates become flush with the truss member surfaces at lower press pressures due to the platens being substantially parallel at the pressures required to completely drive the teeth into the truss mem bers.

The press of the invention can be of lower capacity than that required using presses of prior art constructions or, as an alternative, it can accomplish more work at its rated capacity. For example, experimental data shows that approximately 35 /2 tons of pressure was required to drive a particular connector plate into wood truss members using a conventional press having platen surfaces which are parallel prior to being loaded and whose centers are in line with the axis of the press cylinder. Using a press of this invention the same connector plate can be fully and completely driven into the same type and size of wood truss members using only about 26 tons of pressure. In this example the press of the invention accomplished about 40% more work. It has also been found that the press weight for a given capacity press can be decreased by about 25% or the equivalent capacity of the press can be increased about 60%. Thus it will be seen that the press construction of this invention is highly eflicient, permits a smaller press to accomplish a given work load, and reduces the weight'of the press which in turn will reduce the cost of manufacturing the press. At the same time, improved pressing results are achieved in many applications, such as in driving connector plates where unequal forces on opposite edges of a plate will cause collapsing of the teeth. Moreover, the teeth are driven completely into the wood throughout the length and breadth of the plate, thus producing a better splice.

The press construction of the invention is useful not only for overhead suspension type presses of the type illustrated but also for floor mounted presses. The press structure may be used in pneumatic as well as hydraulic presses.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A press comprising a press body of generally C- shape having "a base and two arms projecting from the ends of the base, first and second platens carried by the press body, each of the platens having a fiat surface, power means for moving the second platen surface toward and away from the first platen surface on an axis offset away from the base of the press body from the centers of the platen surfaces whereby a compressing force can be applied to and removed from work between the platens, said platen surfaces being substantially parallel when a compressive force is exerted on generally parallel faces of the work by operation of the power means.

2. A press as set forth in claim 1 wherein the platen surfaces are nonparallel to each other prior to the application of a compressing force to work by operation of the power means and the platen surfaces become substantially parallel when a sufliciently large compressive force is being exerted on the work.

3. A press as set forth in claim 2 wherein the platens are between the arms and adjacent the base, the edges of the platen surfaces nearest the base being further apart than the opposite edges of the platen surfaces prior to the application of a compressing force to the work.

4. A hydraulic press comprising a press body of generally C-shape, said body being closed at one side, a first platen carried by the press body, a hydraulic cylinder open at one end, the cylinder being mounted on the body with its open end facing the first platen so that an extension of the central axis of its bore passes through the first platen, an elongate ram having an inner end positioned within the cylinder and an outer end projecting from the open end of the cylinder toward the first platen, means on the inner end of the ram slidably and sealingly engaging the inner surface of the cylinder and forming a piston, ports through the side and the other end of the cylinder for introducing hydraulic fluid into and removing it from the cylinder whereby the ram can be moved axially of the cylinder toward and away from the first platen under control of hydraulic fluid introduced into the cylinder through the ports, a second platen attached to the outer end of the ram for movement with the ram toward and away from the first platen to apply and remove a compressing force from work between the platens, each of the platens having a fiat surface facing the other platen, the center of one platen surface being aligned with the center of the other platen surface when the second platen is moved toward the first platen, the central axis of the cylinder being ofiset away from the closed side of the body from the centersof the platen surfaces, the platen surfaces being nonparallel to each other prior to the ap plication of a compressing force to the work by operation of the press, said platen surfaces being adapted to assume a substantially parallel relation when a sufficiently large compressive force is exerted on generally parallel faces of the work by operation of the press.

5. A hydraulic press as set forth in claim 4 wherein the press body has two spaced arms projecting from opposite ends of a base, the base being at the closed side of the press body, and the cylinder and first platen are carried by the frame arms at the open side of the body.

6. A hydraulic press as set forth in claim 5 wherein the edges of the surfaces of the first and second platens nearest the base of the body are further apart than the opposite edges of the platens prior to the application of a compressing force to work by operation of the press.

7. A hydraulic press as set forth in claim 4 wherein the ram comprises a tube closed to the passage of hydraulic fluid, the outside diameter of the tube being only slightly smaller than the inside diameter of the cylinder, and the means forming a piston comprises annular bushings and a packing mounted on the outer surface of the inner end portion of the ram for sliding and sealing engagement with the inner surfaceof the cylinder. 8. A hydraulic press as set forth in claim '7 further comprising bushings and a packing mounted on the inner surface of the cylinder adjacent its open end slideably and sealingly engaging the ram outer surface, said packings and said bushings on both the cylinder and the ram being substantially the same diameter.

9. A hydraulic press as set forth in claim 4 wherein the platen surfaces are nonparallel to each other prior to the application of a compressing force to the work by operation of the press, said platen surfaces being adapted to assume a substantially parallel relation when a sufficiently large compressive force is exerted on generally parallel faces of the work by operation of the press.

References Cited UNITED STATES PATENTS 1,256,351 2/1918 Miller 100269 XR 2,296,051 9/1942 Pocock et al 100231 3,207,406 9/1965 Bowman 227-152 3,247,783 4/ 1966. Hammon 100231 XR FOREIGN PATENTS 554,810 7/1932 Germany. 430,999 6/ 1935 Great Britain.

BILLY I. WILHITE, Primary Examiner.

Claims (1)

1. A PRESS COMPRISING A PRESS BODY OF GENERALLY CSHAPE HAVING A BASE AND TWO ARMS PROJECTING FROM THE ENDS OF THE BASE, FIRST AND SECOND PLATENS CARRIED BY THE PRESS BODY, EACH OF THE PLATENS HAVING A FLAT SURFACE, POWER MEANS FOR MOVING THE SECOND PLATEN SURFACE TOWARD AND AWAY FROM THE FIRST PLATEN SURFACE ON AN AXIS OFFSET AWAY FROM THE BASE OF THE PRESS BODY FROM THE CENTERS OF THE PLATEN SURFACES WHEREBY A COMPRESSING FORCE CAN BE APPLIED TO AND REMOVED FROM WORK BETWEEN THE PLATENS, SAID PLATEN SURFACES BEING SUBSTANTIALLY PARALLEL WHEN A COMPRESSIVE FORCE IS EXERTED ON GENERALLY PARALLEL FACES OF THE WORK BY OPERATION OF THE POWER MEANS.

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