US3848525A

US3848525A - Control means for opposed rams of a press

Info

Publication number: US3848525A
Application number: US00393237A
Authority: US
Inventors: F Kent; S Steinbrook
Original assignee: Wean United Inc
Current assignee: WEAN INCORPORATED A CORP OF PA; Mitsui Engineering and Shipbuilding Co Ltd
Priority date: 1973-08-30
Filing date: 1973-08-30
Publication date: 1974-11-19
Anticipated expiration: 1991-11-19
Also published as: FR2242235B1; IT1018852B; JPS5050772A; FR2242235A1; CA1007929A; DE2437102A1; GB1441376A

Abstract

In an hydraulic press having opposed work performing rams a control for synchronizing the movements of the rams during their working strokes comprises several sets of limit switches for each ram arranged in the direction of the travel of the rams, the switches of similar sets being coordinated to interrupt the movement of the rams in the event an undesirable degree of travel occurs in one ram as compared with the other.

Description

United States Patent 11 1 1111 3,

Kent et al. Nov. 19, 19 74 54] CONTROL MEANS FOR OPPOSED RAMS 2,729,943 1/1956 03116 et al. 91 /171 3,050,809 8/1962 Kupka 100/264 X OF A PRESS 3,435,719 4/1969 Wythe 83/623 [75] Inventors: Francis J sep ent, 1 g o 3,648,565 3/1972 PlObSI et al 91/171 Seymour E. Steinbrook, wynnewood both of Primary Examiner-Billy J. Wilhite [73] Assignee: Wean United, Inc., Pittsburgh, Pa. Attorney, Agent, or Firm-Henry C. Westin; Daniel 22 Filed: Aug. 30, 1973 Patch [21] Appl. No.: 393,237

[57] ABSTRACT [52] US. C 100/264, 20 In an hydraulic press having opposed work performing 91/171 rams a control for synchronizing the movements of the [51] Int. Cl. B30b 15/18 rams during their working strokes comprises several Field of Search 1 4, sets of limit switches for each ram arranged in the di- 269 rection of the travel of the rams, the switches of simi- 91/171 lar sets being coordinated to interrupt the movement I of the rams in the event an undesirable degree of [56] References Cited travel occurs in one ram as compared with the other.

UNlTED STATES PATENTS 3 Cl 3 D F 2,636,350 4/1953 AICOIII 91 171 rawmg gums Pmmm rm 1 91314 sum 2 BF 2 RAM 30 RAM 40 UPPER RAM CONTROL FIG. 3'

[' l I l l l I s LOWER RAM CONTROL 2 G F O 5 ll BB BBBB 65432| S$$$$$ LL L.LLL T1 l; IL

CONTROL MEANS FOR OPPOSED RAMS OF A PRESS It is highly desirable in certain pressing operations where there are employed opposed travelling work performing rams to maintain the travel of the rams within a predetermined degree of synchronization. This is particularly highly desirable in press operations like compacting a deep stack of loose material which should be compressed simultaneously'from both ends. The purpose is obtaining uniformed density in the compact by equalizing the effect of the friction on the walls of the container which encloses the material.

The present invention provides a control for assuring in a simple, economical and trouble-free manner the synchronization of opposing travelling work performing rams of a press and for adjusting the degree of synchronization.

More particularly, the present invention provides a control means including a set of at least two movement detecting means for each ram arranged to be operated by their respective associated rams, and means coordinating the sets of movement detecting means in a manner to interrupt movement of the rams in the event an undesirable degree of travel occurs in one ram as compared with the other ram until the lagging ram reaches a desired synchronized position to the interrupted ram.

Still more particularly, the present invention provides a control means for the purpose noted above comprising several sets of coordinated limit switches for each ram arranged in spaced relationship in the direction of the working stroke of the rams, means for coordinating similar sets, as determined by their particular positions to their associated rams, so that the rams will continue to move towards each until the limit switches of the related sets are operated by their associated rams.

Another object of thepresent invention is to provide a control of the type described immediately above in which the limit switches are constructed and arranged so that initially on operation of the rams certain limit switches are closed and are opened on engagement by their associated rams and other limit switches are opened and are closed by engagement by their associated rams, the limit switches that are opened serving to interrupt travel of their associated ram until the other limit switches have been closed.

Another object of the present invention is to adjust the degree of synchronization so that either ram does not advance far ahead of the other, but that, on the other hand, its movement is not interrupted unnecessarily if the difference in the travel of both rams is within acceptable limits.

These objects, as well as other novel features and advantages of the present invention will become more apparent when the following description of one embodi ment thereof is read along with the accompanying drawings of which:

FIG. 1 is an elevational view of a double-ramhydraulic press incorporating the features of the present invention; I

FIG. 2 is an enlargement of the ram displacement synchronization control shown in FIG. 1, and

FIG. 3 is a schematic electrical control circuit for the control shown in FIG. 2.

In referring first to FIG. 1, there is shown in outline form an hydraulic press 10 having three vertically arranged tension columns l2, l4, and 16, and tied together at the top and bottom by entablatures l8 and 20, respectively. The top entablature carries a number of

piston cylinder assemblies

22, 24, and 26, the ram ends of which are connected to a crosshead 28 with whichthere is associated a top ram 30. Likewise, the bottom entablature 20 carries a number of

piston cylinder assemblies

32, 34, and 36, having their rams connected to a crosshead 38 with which there is associated-a working ram 40.

It will be appreciated that the illustrated press 10 may follow several well-known forms and for which reason further description of the structure and operation of the press will not be given. It will be helpful, however, to note that associated with the press 10 is a turntable 42 for receiving a number of containers, two being shown at 44 and 46, which serve to transfer the material to be compacted between the

rams

30 and 40 and after the compacting is completed to move the formed workpiece away from the press while at the same time bringing a new container between the rams.

As noted before, it is important that the

rams

30 and 40 during their working stroke move in a synchronized relationship. As has been noted, the present invention provides a control that in a simple and trouble-free manner accomplishes this purpose. Part of the control is shown in general form in FIG. 1 by the two

control boxes

48 and 50 arranged adjacent to the upper and lower

movable crossheads

28 and 38, respectively. The

control boxes

48 and 50 are best shown in FIG. 2 which illustrates that each control box is made up of a number of limit switches, the upper employing the letter A and the lower box employing the letter B," such as LS-lA through 6A and LS-IB through 68, respectively. The lower numbers identify the limit switches closest to their

respective crossheads

28 and 38.

The limit switches can, be of several well-known types, the one being employed in the illustrated embodiment, although not shown, being of a roller-arm cam type. The schematic horizontal lines in FIG. 2 associated with each limit switch represent their lever arms and the vertical lines extending between two adjacent switches to form cooperative pairs represent the comparative distances between each pair. These distances determine the degree of synchronization and are adjustable. As shown, the distance between the pairs of switches become progressively smaller as the crossheads move towards the final pressing stage since synchronization is less important at the beginning of the stroke of the

rams

30 and 40 than at the ends.

The electrical circuit for the limit switches LS-lA to 6A and LS-lB to 6B is shown in FIG. 3. It includes two power lines 52 and 54 connected together by a line 56 having a switch 58 shown in its opened position. FIG. 3 shows the coordinated relationship of the limit switches in which it will be noted that limit switches LS- lA-3A and 5A are employed in parallel with limit switches LS-2B, 4B and 6B, respectively, and similarly limit switches LS-lB-3B and 5B are arranged in parallel with limit switches LS-2A-4A6A, respectively. Each of the two interrelated groups of limit switches are associated with the different one of the

rams

30 and 40, each ram being controlled by a relay, theupper ram by relay 1CR and the lower ram by relay 2CR arranged in a line 60.

As shown, LS-2B-4B-6B and LS-2A-4A-6A are initially closed whereas limit switches LS-lA-3A-5A, 1B, 3B, and B are initially opened.

In this way, in referring for example to the cooperative sets of limit switches 2-A and 1B and 1A and 28 current is allowed to pass over

lines

56 and 60 to operate the relays lCR and 2CR to effect initiation of the operation of both

rams

30 and 40. In examining the operation of the circuit of FIG. 3 from first the standpoint of maintaining the rams operative when they are advancing at a proper rate of speed, as the crosshead first trips their respective limit switches LS-IA and 18, these limit switches are closed and remain closed. Current therefore passes to the relays lCR and 2CR through the contacts of limit switches LS-lA and LS-lB even after the crossheads have tripped switches LS-2B and LS-2A, and opened their contacts. If the rams are still proceeding synchronously limit switch 3A and LS-3B will be closed and remain closed and the rams will continue to function even though limit switches 8-4A and 4B are contacted and opened and remain opened.

The same procedure takes place between the sets of limit switches 5B-6A and 6B-SA. If however, one of the rams move slower or faster than the other ram, say for example, the ram 40 lags behind the ram 30, and assuming that this takes place at the very start of the operation of the rams, the faster ram 30 will close limit switch LS-lA and the current will pass over the line 60 to the relay 2CR of the ram 40 through both limit switches LS-2B and LS-1A. As the ram 30 contacts limit switch LS-2A, this limit switch will be opened and since the ram 40 has not yet closed limit switch 18, the operation of the ram 30 will be interrupted until the lagging ram 40 advances to trip the limit switch IE to close this switch, which will then remain closed as LS-2A will remain opened. Thus, the control illustrated in FIG. 3 is designed to control the synchronization of the

rams

30 and 40 in designated zones irrespective of which ram is the lagging ram and irrespective of where the difference in speed takes place.

In accordance with the provisions of the patent statutes, we have explained the principles and operation of our invention and have illustrated and described what we consider to represent the best embodiment thereof.

We claim:

1. In a press having opposed rams and means for causing said rams to advance towards each other during their working strokes,

a control means including a set of at least two movement detecting means for each ram arranged to monitor the movements of their associated rams,

said detecting means forming zones of variable lengths, and

means for coordinating said sets of movement detecting means in a manner to interrupt movement of one of the rams in the event an undesirable degree of travel occurs in one ram as compared with the other until the lagging ram reaches a desired synchronized position to the interrupted ram.

2. In a press in accordance with claim 1, wherein said sets of movement detecting means include several sets of coordinated limit switches for each ram arranged in spaced-relationship to the direction of travel of said rams in a manner to form zones of variable lengths,

means for coordinating similar sets of limit switches with respect to the path of travel of their associated rams in a manner to synchronize the travel of the rams by causing interruption of the operation of an advancing ram and a continuation of the operation of a lagging ram until all the limit switches of related sets have been operated on by their associated rams.

3. In a press according to claim 2, wherein said limit switches are constructed and arranged so that initially on operation of the rams a limit switch of each set is closed and is opened and remains opened on movement of their associated rams and a second limit switch of each set is opened and is closed and remains closed by movement of their associated rams, the limit switch of each set that is opened serving to interrupt a travel of their associated rams until the limit switch of the same set has been closed.

Claims

1. In a press having opposed rams and means for causing said rams to advance towards each other during their working strokes, a control means including a set of at least two movement detecting means for each ram arranged to monitor the movements of their associated rams, said detecting means forming zones of variable lengths, and means for coordinating said sets of movement detecting means in a manner to interrupt movement of one of the rams in the event an undesirable degree of travel occurs in one ram as compared with the other until the lagging ram reaches a desired synchronized position to the interrupted ram.

2. In a press in accordance with claim 1, wherein said sets of movement detecting means include several sets of coordinated limit switches for each ram arranged in spaced-relationship to the direction of travel of said rams in a manner to form zones of variable lengths, means for coordinating similar sets of limit switches with respect to the path of travel of their associated rams in a manner to synchronize the travel of the rams by causing interruption of the operation of an advancing ram and a continuation of the operation of a lagging ram until all the limit switches of related sets have been operated on by their associated rams.