CA1063925A - Shock dampening systems for presses - Google Patents
Shock dampening systems for pressesInfo
- Publication number
- CA1063925A CA1063925A CA293,352A CA293352A CA1063925A CA 1063925 A CA1063925 A CA 1063925A CA 293352 A CA293352 A CA 293352A CA 1063925 A CA1063925 A CA 1063925A
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- CA
- Canada
- Prior art keywords
- slide
- fluid
- chamber
- press
- valve
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D28/00—Shaping by press-cutting; Perforating
- B21D28/02—Punching blanks or articles with or without obtaining scrap; Notching
- B21D28/20—Applications of drives for reducing noise or wear
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Control Of Presses (AREA)
- Shearing Machines (AREA)
- Punching Or Piercing (AREA)
Abstract
SHOCK DAMPENING SYSTEMS
FOR PRESSES
Abstract of the Disclosure A hydraulic fluid shock dampening system is disclosed for a shearing press to minimize shock and vibration imposed on the press following breakthrough of the material being sheared by cutting die components carried by the press bed and slide.
The system includes cylinder and piston units interposed between the press bed and slide each providing a variable-volume fluid receiving chamber from which fluid under pressure is expelled during movement of the slide toward the bed to achieve a shearing operation. A flow sensitive shutoff valve is responsive to accelerated movement of the slide upon breakthrough to block fluid flow from the chambers and thus restrain further slide movement toward the press bed.
FOR PRESSES
Abstract of the Disclosure A hydraulic fluid shock dampening system is disclosed for a shearing press to minimize shock and vibration imposed on the press following breakthrough of the material being sheared by cutting die components carried by the press bed and slide.
The system includes cylinder and piston units interposed between the press bed and slide each providing a variable-volume fluid receiving chamber from which fluid under pressure is expelled during movement of the slide toward the bed to achieve a shearing operation. A flow sensitive shutoff valve is responsive to accelerated movement of the slide upon breakthrough to block fluid flow from the chambers and thus restrain further slide movement toward the press bed.
Description
Disclosure The present invention relates to the art of presses and, more particularly, to a hydraulic fluid shoc~. dampening system for a shearing press In a shearing press, as is well known, cooperable cutting die or shearing components are mounted on the press slide and bed to achieve cutting or shearing of material there-between in response to movement of the press slide through the downward portion of its total stroke. Upon engagement of the die component on the slide with the material to be severed a load is placed on the press which progressively increases to a maximum which is reached at the point of break-through of the die components with respect to the material ,. , . . . . .
, : .. : , . .
, 10~39Z5 i therebetween. This load is imposed on the press through the slide, and movement of the slide toward the press bed is restrained during the severing operation. This restraint is removed upon breakthrough, whereupon slide movement toward the press bed is accelerated as a result of the load build up.
In the absence of a restraining force with respect to such accelerated movement of the slide, objectional shock loads and vibration forces are set up within the press. Such shock and vibration is detrimental to press life as well as maintenance expenses in connection with component parts of the press. Moreover, these shock and vibration forces result in objectionably high noise levels and impar~ un-desirable vibration to otner equipment and to the personnel working in the vicinity of the press. Moreover, it will be appreciated that these undesirable characteristics are repeated with each stroke of the press and are related in degree of objectionability to the size of the press Efforts have been made heretofore to dampen such shock and vibration forces experienced with the operation of a shearing press. While some success has been achieved in connection with reducing shocX and vib~ation, the systems heretofore proposed for ~his purpose do not provide optimum efficiency with regard to vibration and noise abatement over a desirable period of continuous use of a given press, Addi-tionally, systems heretofore proposed have characteristicswhich are detrimental to press life and economical press operation. With regard to such prior art efforts, it has been proposed, for example, to employ a hydraulic shock absorbing syS~eM including one or more piston and cylinder units inter-po~ed betwaen the press bed and slide to define chambers 10~39ZS
receiving hydraulic fluid under pressure. During movement of the slide toward the bed to achieve a shearing operation~
fluid is expelled from the chamber or chambers through a vari-able restricted passageway incorporated in the piston component and adjusted to provide a predetermined restriction to flow from the chamber at the point of breakthrough of the material being severed. Such a system enables continuous, though re-stricted, movement of the slide following breakthrough and, thus, the imposition of some shock and vibration forces on the press. Moreover, if two or more such piston and cylinder units are employed in a given press, the adjustment thereof must be extremely accurate to avoid eccentric loading of the -slide as a result of different pressure drops across the restrictions of the different units. Still further, the -accuracies required in these units makes the system extremely expensive, and continuous operation of the press results in a requirement fbr frequent adjustment of the units ~hereby --;-down time of the press is undesirably high as is maintenance ~ -time and expense. Additionally, continuous operation of the press with continuous flow of hydraulic fluid from the --cylinder chambers each time the slide strokes results in undesirably high fluid temperatures which may necessitate the use of a cooling system therefor, thus adding to the ~
cost of production and expensive operation of the press. -~-Still further, even if just one piston and cylinder unit is - employed to avoid the possibility of eccentric loading of the slide, the accuracy required with regard to adjusting the --point of maximum restriction to coincide with the point of material breakthrough is impractical.
Other systems heretofore proposed have included _ 3 _ :, ~
' ., ' " :
~0~39Z5 a ~ixed orifice in the hydraulic system operable to pass hydraulic fluid from a fluid receiving chamber to a tank or the like by a low pressure drop during initial cutting of the material and at a high pressure drop when break-through occurs. The high pressure drop provides a restrain-ing force against the slide. Systems of the latter character have poor efficiency with regard to reducing shock and noise and, additionally, generate excessive heat in the fluid due to the substantially continuous flow thereof under pressure.
In accordance with the present invention, the disadvantages of previous shock dampening systems provided in connection with shearing presses, including those speci-fically enumerated hereinabove, are minimized or overcome.
In this respect, maximum restraint of slide movement following breakthrough is achieved by quickly and positively blocking fluid flow from hydraulic fluid receiving chambers inter-posed between the press slide and bed. This maximum re-straining force provides increased efficiency in reducing shock and noise by minimizing the load energy released and thus slide movement following breakthrough. Moreover, by positively blocking fluid flow from the chamber or chambers there is very little heat generated in the system fluid.
Accordingly, the necessity of cooling systems are avoided as is the danger of excessive heat in the system without such a cooling system.
Preferably, such shutoff of fluid flow from a fluid chamber at the point of breakthrough is achieved by a flow sensitive valve in the fluid system whîch is responsive to acceleration of the slide at the point of breakthrough to block fluid flow from the chamber or chambers. Further, ~063925 the shock and v-~bration loads imposed on the press by energy release at breakthrough can be further reduced by using a minimum volume of hydraulic fluid in the system, by using a fluid having a high bulk modulus, and by rapid response of the flow sensitive valve. Preferably, the flow sensitive shutoff valve provides restricted flow from the chamber or chambers with minimal pressure drop during the cutting operation up to the point of breakthrough.
At the point of breakthrough, acceleration of the slide posi-tively shuts the valve producing a rapid counterload againstslide movement, thus reducing the energy release experienced at breakthrough and maintaining the load on the press through the slide, thus to minimize shock, vibration and noise. -~
It is accordingly an outstanding object of the present invention to provide an improved hydraulic shock dampening system for shearing presses.
; Another object is the provision of a shock dampening system of the foregoing character which minimizes energy release, with respect to the load on the press, upon break-through of the material being severed.
Yet another object is the provision of a shock dampening system of the foregoing character which effficiently -~
minimizes the imposition of shock and vibration forces on a -press and the resultant noise level of the press during shearing operations.
Still a further object is the provision of a shock dampening system of the foregoing character ~hich positively blocks fIuid flow from an expansible chamber unit interposed between the press slide and bed at breakthrough of the material being severed, thus to minimize energy release with respect .
to the slide at the point of breakthrough and maximize slide restraining force.
Yet another object lS the provision of a shock dampening system of the foregoing character in which a flow 5 . sensitive valv~ is employed to permit restricted flow of -hydraulic fluia from the expansible chamber device duri~g cutting of material up to the point of brea~through and which is responsive to acceleration of the slide at the point of breakthrough to close the valve and thus block further fluid .
flow from the expansible chamber device Still another object is the provision of a shock dampening system of the foregoing character which i9 in- . .
expensive to manufacture and install and which is highly efficient in operation throughout long periods of continuous use, thus minimizing down time of the press and maintenance : -time and expense.
According to a broad aspect the present invention relates to a hydraulic shock dampening system for a shearing !;
. . . ~
press having fra~e means including bed means and supporting :
reciprocable slide means and wherein material is severed between .
cooperable shearing means supported by said bed and slide means, ~.-- said system including hydraulic fluid receiving variable volume chamber means between said bed means and slide means and con-nected to a source of hydraulic fluid under pressure, said - i 25 chamber means being operable under compression in response to ,-breakthrough of material being sneared by said sl-earing means supported by said slide means to restrain the resulting accelerated movement of said slide means, the improvement ~::
comprising: shutoff valve means in fluid flow communication with said chamber means, said valve means having opened and closed modes, and means completely closing said valve means in response to said accelerated movement of the press slide ~
to prevent any fluid flow from said chamber means. . .
-6- .
i~ . .
i ( 10~3~ZS
The foregoing objects, and others, wlll ln part be obvious and in part pointed out more fully hereinafter in con~unction with the written description of preferred embodiments of the invention shown in the accompanying drawings in which:
FIGURE 1 is a schematic illustration of a shock dampening system in accordance with the present invention associated with the slide and bed components of a shearing press;
` FIGURE 2 is a graph showing slide displacement and press load curves during the working stroke of a shearing press without shock dampening;
FIGURE 3 is a graph showing slide displacement and press load curves during the work stroke of a shearing ." .' .
: 20 ~- .
' - 6a -lOG39Z5 press having a shock dampening s~stem in accordance with the present invention; and, FIGURE 4 is a schematic illustration of a modifica-tion of the system sho~n in FIGURE 1.
Referring now in greater detail to the drawings wherein the showings are for the purpose of illustrating preferred embodiments of the present invention onl~ and not for the purpose of limiting the same, a hydraulic fluid shock dampening system is schematically illustrated in ; FIGUR~ 1 and in conjunction with a shearing press 10 operable, fo~ example, to cut blanks from metal sheets. The structure and operation of presses of this character are of course well known in the art, and details regarding the structure and operation are not necessary to an understanding of the present invention. It will be sufficient to appreciate that the press has a ~rame 12 providing a press bed 14 and that the frame supports a slide 16 for reciprocation toward and away from bed 14, a suitable drive arrangement being provided to achieve such reciprocation. As is further well known in the shearing press art, bed 14 supports a shearing component 18 and slide 16 supports a shearing component 20 cooperable with component 18 to cut material therebetween during down-ward movement of slide 16 to the bottom dead center position thereof. Cutting takes place, of course, from a point along tne slide stroke above the bottom dead center position at which shearing component 20 engages the material to a second point :;; . , 10ti39Z5 along the slide path ~ust ahead of bottom dead center at which shearing components 18 and 20 cooperatlvely break through the material being cut. As is well known to those skilled in the art of presses, engagement of material to be cut between shearing components 18 and 20 during downward movement of the slide imposes a load on the press through the slide and which load is suddenly released upon breakthrough of the material, whereupon down~ard movement of the slide is accelerated in the direction toward the bottom dead center position thereof. This is of course accompanied by release of the energy stored by loading of the press during the shearing operation.
In accordance with the present invention, a shock dampening system is associated with the slide and frame components of the press to minimize downward displacement of the press slide following breakthrough, thus to minimize ; the release of energy resulting from loading of the press up to the point of breakthrough. The shock dampening system, designated generally by the numeral 22 in FIGURE 1, is a hydraulic system including hydraulic fluid receiving variable volume devices 24 mounted on or supported relative to the press bed for actuation by slide 16 during downward movement thereof toward the bottom dead center position. In the embodiment shown, each variable volume device 24 is in the form of a piston-cylinder assembly including a cylinder 26 supported on the press bed and a piston 28 supported within cylinder 26 for vertical reciprocation relative thereto.
The space in cylinder 26 behind piston 28 defines a fluid receiving chamber 30, and cylinder 26 is provided with a common inlet and outlet passage 32 opening into chamber 30.
Slide 16 carries an actuator pin 34 for each piston, and each pin 34 has its upper end threadedly interengaged wit'n a support collar 36 on the slide so that the pin is vertically adjustable relative to the slide for the purpose set forth hereinafter.
Chambers 30 of variable volume devices 24 are con-nected to a common source of hydraulic fluid under pressure.
~lore particularly, in the embodiment shown in FIGURE 1 a motor-pump unit 38 is adapted to deliver hydraulic fluid under pressure to cha~bers 30 fr~m a source 40 through a flow line system including a flow line 42 and branch lines 44 and 46 connected thereto and to one of the passageways 32 of variable volume devices 24. A one way check valve 48 - prevents backflow to source 40, and a pressure responsive unloading valve 50 is operable at a predetermined pressure between valve 48 and the motor-pump unit to return hydraulic fluid to the source when valve 48 is closed and the pressure between the latter valve and motor-pump unit 38 exceeds the setting of valve 50.
A noramlly open fluid flow sensitive shutoff valve 52 is provided in flow line 42 to control fluid flow through the latter line. Valve 52 includes a restricted passageway 54 permitting restricted fluid flow in the direction between chambers 30 and source ~0 when valve 52 is in the open position illustrated in FIGURE 1. Valve 52 further includes a closed passageway 56 which is adapted to blocX fluid flow through line 42 when valve 52 is in the closed position in which pa~sage 56 would be shifted to the right in FIGURE 1 to a position in ~lignement with flow line 42. Valve 52 is normally biased to the open position such as by a spring 58 g , .
1~39ZS
and is adapted to be biased to the right in FICURE 1 by fluid under pressure from branch lines 44 and 46 acting thereagainst tlrough a feed line 60, as described in greater detail here-inafter. For the purpose set forth hereinafter, a low pressure hydraulic fluid receiving accumulator 62 is connected to flow line 42 between valves 48 and 52, and a high pressure hydraulic fluid receiving accumulator 64 is connected in fluid communi-cation with line 42 and branch lines 44 and 46 between valve 52 and chambers 30 of variable volume devices 24.
Operation of the shock dampening arrangement described above will be best understood by referring to FIGURES 2 and 3 of the drawing together with FIGURE 1. Briefly, FIGURES 2 and 3 are graphs showing slide displacment and press load during movement of the slide through the shearing stroke. FIGURE 2 shows the effect of no shock dampening of the slide, and FIGURE 3 shows the effect of the shock dampening system described above and the effect of prior art shock dampening : systems. In both graphs, the point 1 represents the time during the slide stroke at which, in the system disclosed herein, pins 34 engage pistons 28 during movement of the slide toward the bottom dead center position thereof which is indicated BDC in FIGURES 2 and 3. Point 2 represents the time at which the shearing components engage the material to be severed, and point 3 represents the time at which breakthrough of the material by the shearing components .
occurs. Curve L represents the load imposed on the press during a severing operation, and curve D represents the position of the slide during the severing operation relative to bottom dead center. If the press was not loaded by the interposition of material to be cut between the shearing 10~3g25 components, slide displacement curve D would be arcuate throughout its extent and thus would follow the arcuate portion D' between point 2 and BDC in FIGURE 2 and between points 2 and 4 in FIGURE 3. The significance of point 4 is set forth hereinafter.
- With regard now to the operation of the shock dampening arrangement described hereinabove, the components of the press and hydraulic system are in the positions illustrated in PIGURE
1 prior to a shearing operation. Hydraulic fluid is delivered under pressure from source 40 to chambers 30 through flow line 42, restricted passage 54 of valve 52 and branch lines 44 and 46, and the fluid under pressure in chambers 30 biases pistons 28 upwardly. As slide 16 moves downwardly toward bed 14, pins 34 engage pistons 28 just before shearing components 18 and 20 engage the material therebetween to be severed. The ad~ustability of pins 34 enables setting the pins in this respect. As mentioned above, the material is engaged at point 1 in the graphs of FIGURES 2 and 3 and at this time the slide is located ~-,~
a distance S above BDC. Continued downward movement of slide 16 causes downward movement of pistons 28 in cylinders 26 thus forcing the hydraulic fluid in chambers 30 into branch lines 44 and 46 through cylinder passages 32. This fluid from chambers 30 flows back toward source 40 through restricted passage 54 of valve 52 and, since one way valve 48 is closed against return of fluid to source 40, accumulator 62 receives the back flow fluid - under pressure and stores the latter for return towards chambers 30 as set forth hereinafter. During this movement of the slide toward its bottom dead center position the slide has a normal velocity which is a known factor in connection with a given press and ,:
, .
10~392S
shutoff valve 52 is structured for this normal velocity to produce a minimal pressure drop through restricted passage 54, whereby the opening bias is sufficient to maintain valve 52 open.
Continued downward movement of slide 16 brings shearing components 18 and 20 into engagement with the material there-between, thus initiating the imposition of a losd on the press through the slide. This engagement with the material is re-presented by point 2 in the graphs, and at this time the slide is spaced a distance W above the bottom dead center position thereof. As the shearing components cut the material, pins 34 continue to depress pistons 28 and the loading of the press restrains advancement of the slide and reduces the velocity thereof. Accordingly, the piston displacement is gradual causing a continuance of the foregoing fluid flow from chambers 30 through restricted passage 54 of valve 52 to accumulator 62.
As will be seen from load curve L in the graphs, the press is loaded from zero to a maximum as the shearing components move through the material during the period of slide displacement represented between points 2 and 3. At the same time, it will be seen that the material between the shearing components restrains displacement of the slide in the downward direction towards bottom dead center, as represented by portion D2 of the displacement curve in the graphs.
The shearing components breakthrough the material at point 3 whereby the load is removed from the press and the stored energy of the load is imposed on the slide causing a rapid acceleration of the slide towards its bottom dead center position. In the absence of any shock dampening ~063925 o~ the slide a~ this point, the slide is immediately acceler~ted to bottom dead center, thereby imposing shock on the press and bounce of the slide resulting in the imposition of a series of reverse direction loads on the press as indicated by the portion of load curve L to the right of point 3 in FIGU~E 2.
A shock dampening system in accordance with the present invention advantageously restrains slide displacem~nt toward BDC following breakthrough and minimizes the energy release so as to maintain a load on the~press during completion of the severing operation. In this resp,ect, with reference to FIGURE 1, acceleration of the slide which occurs upon breakthrough is transmitted to pistons 28, thus suddenly accelerating displacement of the pistons in the direction to reduce the volume of chambers 30. This sudden displace-ment increases the velocity of the hydraulic fluid ~lowing from ; chambers 30, whereby valve 52 is actuated through feed line 60 to close the valve and thus positively ~lock fluid flow from chambers 30. Thus, as seen in FIGURE 3, load energy release is stopped at point 5 following breakthrough and the slide ~-is restrained from reaching BDC, as represented by portion ~3 of the slide displacement curve. Accordingl~, a major pro-portion of the load is maintained on the press following breakthrough. From the point of time in normal slide displace-ment at which B~C is reached the press load i5 progressively decreased as a result of movement of the slide drive components which would normally cause upward displacement of the slide from ~DC. At point 4 in the graph of ~IGURE 3, the slide drive components are in slide displacement positions corres-pondin~ to the displacement position in which the slide is held by the piston-cylinder units 24. Thereafter, the slide , 1063~Z5 drive components move the slide up~ar~ly and thc load on the press is reduced to zero.
The load maintained on the press in this rnanner maintains the hydraulic fluid between chambers 30 and valve 5~ under pressure to maintain valve 52 closed. Upon upwa-d movement of slide 16, the fluid pressure in the system biases pistons 28 upwardly to reduce s~stem pressure and thus provide for spring 58 to open valve 52. Thereafter, fluid accumulated under pressure in accumulator 62 is released to flow through L0 restricted passage 54 of valve 52 back into branch lines 44 and 46 and chambers 30 to fully bias pistons 28 to their uppermost positions. Motor-pump unit 38 is operable to replenish any fluid leakage from the system which might occur during operation o~ the press.
High pressure accumulator 64 is a safety device to prevent damage as a result of press overload. If, far example, there is some breaXdown which causes the press slide to impose a high pressure on the hydraulic system between piston-cylinder units 24 and check va}ve 48, accumulator 64 is actuated to receive fluid under such excess pressure.
The embodiment of the present invention illustrated in FIGURE 4 is the same in many xespects as that shown in FIGURE 1 and, accordingly, like numerals are employed in FIGU~ES 1 and 4 to designate li~e components. In the embodi-ment of FIGURE 4, restricted passageway 54 of shutoff valve 52 is in communication with source 40 and piston-cylinder units 24 through flow line 42 and a branch line 66 leading to the valve. Additionally, fluid flow through restricted passage 54 in respon~e to downward movement of pistons 28 prior to sO material brea~through is released by a low pressure ch~ck , , - 14 -1~63g25 valve 68 for flow to a sump or the ]ike 70 leadlng back to source 40. In further comparison of this embodlment with that shown in FIGURE 1, high pressure accumulator 64 in FIGURE 1 is replaced by a pressure responsive relief valve 72 which is operable in response to an undesirably high fluid pressure in the system to dump fluid to a sump or the like 74 for return to source 40. Further, low pressure accumulator 62 in FIGURE 1 is replaced by a low pressure accumulator 76 positioned between motor-pump unit 38 and check -~
valve 48 to accumulate fluid under pressure when shutoff valve 52 is closed to provide sufficient fluid for the system to return pistons 28 to their uppermost positions following a severing operation. It will be appreciated that accumulator 76 works in conjunction with motor-pump unit 38 in replenishing the system in this respect.
Operation of the system shown in FIGURE 4 insofar as blocking fluid flow from chambers 30 of piston-cylinder units 24 is the same as that for the system shown in FIGURE 1.
In this respect, initial downward movement of pistons 28 prior to breakthrough is at the velocity of the press slide, whereby valve 52 remains open and fluid expelled from chambers 30 flows through check valve 68 to sump 70. Upon breakthrough, the sudden acceleration of slide 16 and the resulting velocity increase in the fluid flow closes valve 52 to block further flow of fluid from chambers 30 and thus stop downward displace-ment of the slide. When the slide reaches point 4 in the graph of FIGURE 3, system pressure is reduced whereby valve 52 is biased open and pistons 28 are biased to their upper-~- most positions in preparation for the next severing operation.
It will be appreciated in conjunction with both 10~3925 of the embodiments herein disclosed that the magnitude of the load energy release at point 3 in the graph of FIGUR~ 3 can be controlled toward minimization by using a minimum volume of hydraulic fluid in the piston-cylinder units and flow line~, by using a hydraulic fluid having a high bulk modulus, by using a rapid response flow sensltive shutoff valve, and by various combinations of these control possibilities.
While considerable emphasis has been placed on the specific embodiments herein illustrated and described, it will be readily understood that many modifications will be obvious and suggested upon reading the foregoing description .
and can be made without departing from the principles of the present invention. In this respect, for example, while two piston-cylinder units 24 are illustrated, one or more than two such units can readily be associated with a given press structure to provide the desired slide restraint function ; in response to breakthrough, Further, it will be appreciated that variable volume devices other than piston-cylinder units can be employed and that, in connection with piston-cylinder units, the piston-cylinder relationship can be reversed so that the cylinder is a movable component engaged by the press. Still further, while it i~ preferred to employ a flow sensitive shutoff valve permitting restricted fluid flow therethrough prior to breakthrough of the material being severed, it will be appreciated that other shutoff valve structures could be employed, Moreover, it will be appreci-ated that the shutoff valve could be controlled other than by system fluid. For example, the valve could be solenoid actuated to close at the point of breakthrough. It is only ; 30 necessary in accordance with the present invention that the ~,f 1063gZS
shutoff valve b^ act~lated at the point of acceleration of the slide upon breakthrough to positively block fluid flow from the chambers of the variable volume devices.
As many possible embodiments of the present invention may be made and as many changes may be made in the em~odiments herein illustrated and described, it is to be distinctly understood that the ~oreqoing descriptive matter is to be interpreted merely as illustrative of the present invention and not as a limitation.
, : .. : , . .
, 10~39Z5 i therebetween. This load is imposed on the press through the slide, and movement of the slide toward the press bed is restrained during the severing operation. This restraint is removed upon breakthrough, whereupon slide movement toward the press bed is accelerated as a result of the load build up.
In the absence of a restraining force with respect to such accelerated movement of the slide, objectional shock loads and vibration forces are set up within the press. Such shock and vibration is detrimental to press life as well as maintenance expenses in connection with component parts of the press. Moreover, these shock and vibration forces result in objectionably high noise levels and impar~ un-desirable vibration to otner equipment and to the personnel working in the vicinity of the press. Moreover, it will be appreciated that these undesirable characteristics are repeated with each stroke of the press and are related in degree of objectionability to the size of the press Efforts have been made heretofore to dampen such shock and vibration forces experienced with the operation of a shearing press. While some success has been achieved in connection with reducing shocX and vib~ation, the systems heretofore proposed for ~his purpose do not provide optimum efficiency with regard to vibration and noise abatement over a desirable period of continuous use of a given press, Addi-tionally, systems heretofore proposed have characteristicswhich are detrimental to press life and economical press operation. With regard to such prior art efforts, it has been proposed, for example, to employ a hydraulic shock absorbing syS~eM including one or more piston and cylinder units inter-po~ed betwaen the press bed and slide to define chambers 10~39ZS
receiving hydraulic fluid under pressure. During movement of the slide toward the bed to achieve a shearing operation~
fluid is expelled from the chamber or chambers through a vari-able restricted passageway incorporated in the piston component and adjusted to provide a predetermined restriction to flow from the chamber at the point of breakthrough of the material being severed. Such a system enables continuous, though re-stricted, movement of the slide following breakthrough and, thus, the imposition of some shock and vibration forces on the press. Moreover, if two or more such piston and cylinder units are employed in a given press, the adjustment thereof must be extremely accurate to avoid eccentric loading of the -slide as a result of different pressure drops across the restrictions of the different units. Still further, the -accuracies required in these units makes the system extremely expensive, and continuous operation of the press results in a requirement fbr frequent adjustment of the units ~hereby --;-down time of the press is undesirably high as is maintenance ~ -time and expense. Additionally, continuous operation of the press with continuous flow of hydraulic fluid from the --cylinder chambers each time the slide strokes results in undesirably high fluid temperatures which may necessitate the use of a cooling system therefor, thus adding to the ~
cost of production and expensive operation of the press. -~-Still further, even if just one piston and cylinder unit is - employed to avoid the possibility of eccentric loading of the slide, the accuracy required with regard to adjusting the --point of maximum restriction to coincide with the point of material breakthrough is impractical.
Other systems heretofore proposed have included _ 3 _ :, ~
' ., ' " :
~0~39Z5 a ~ixed orifice in the hydraulic system operable to pass hydraulic fluid from a fluid receiving chamber to a tank or the like by a low pressure drop during initial cutting of the material and at a high pressure drop when break-through occurs. The high pressure drop provides a restrain-ing force against the slide. Systems of the latter character have poor efficiency with regard to reducing shock and noise and, additionally, generate excessive heat in the fluid due to the substantially continuous flow thereof under pressure.
In accordance with the present invention, the disadvantages of previous shock dampening systems provided in connection with shearing presses, including those speci-fically enumerated hereinabove, are minimized or overcome.
In this respect, maximum restraint of slide movement following breakthrough is achieved by quickly and positively blocking fluid flow from hydraulic fluid receiving chambers inter-posed between the press slide and bed. This maximum re-straining force provides increased efficiency in reducing shock and noise by minimizing the load energy released and thus slide movement following breakthrough. Moreover, by positively blocking fluid flow from the chamber or chambers there is very little heat generated in the system fluid.
Accordingly, the necessity of cooling systems are avoided as is the danger of excessive heat in the system without such a cooling system.
Preferably, such shutoff of fluid flow from a fluid chamber at the point of breakthrough is achieved by a flow sensitive valve in the fluid system whîch is responsive to acceleration of the slide at the point of breakthrough to block fluid flow from the chamber or chambers. Further, ~063925 the shock and v-~bration loads imposed on the press by energy release at breakthrough can be further reduced by using a minimum volume of hydraulic fluid in the system, by using a fluid having a high bulk modulus, and by rapid response of the flow sensitive valve. Preferably, the flow sensitive shutoff valve provides restricted flow from the chamber or chambers with minimal pressure drop during the cutting operation up to the point of breakthrough.
At the point of breakthrough, acceleration of the slide posi-tively shuts the valve producing a rapid counterload againstslide movement, thus reducing the energy release experienced at breakthrough and maintaining the load on the press through the slide, thus to minimize shock, vibration and noise. -~
It is accordingly an outstanding object of the present invention to provide an improved hydraulic shock dampening system for shearing presses.
; Another object is the provision of a shock dampening system of the foregoing character which minimizes energy release, with respect to the load on the press, upon break-through of the material being severed.
Yet another object is the provision of a shock dampening system of the foregoing character which effficiently -~
minimizes the imposition of shock and vibration forces on a -press and the resultant noise level of the press during shearing operations.
Still a further object is the provision of a shock dampening system of the foregoing character ~hich positively blocks fIuid flow from an expansible chamber unit interposed between the press slide and bed at breakthrough of the material being severed, thus to minimize energy release with respect .
to the slide at the point of breakthrough and maximize slide restraining force.
Yet another object lS the provision of a shock dampening system of the foregoing character in which a flow 5 . sensitive valv~ is employed to permit restricted flow of -hydraulic fluia from the expansible chamber device duri~g cutting of material up to the point of brea~through and which is responsive to acceleration of the slide at the point of breakthrough to close the valve and thus block further fluid .
flow from the expansible chamber device Still another object is the provision of a shock dampening system of the foregoing character which i9 in- . .
expensive to manufacture and install and which is highly efficient in operation throughout long periods of continuous use, thus minimizing down time of the press and maintenance : -time and expense.
According to a broad aspect the present invention relates to a hydraulic shock dampening system for a shearing !;
. . . ~
press having fra~e means including bed means and supporting :
reciprocable slide means and wherein material is severed between .
cooperable shearing means supported by said bed and slide means, ~.-- said system including hydraulic fluid receiving variable volume chamber means between said bed means and slide means and con-nected to a source of hydraulic fluid under pressure, said - i 25 chamber means being operable under compression in response to ,-breakthrough of material being sneared by said sl-earing means supported by said slide means to restrain the resulting accelerated movement of said slide means, the improvement ~::
comprising: shutoff valve means in fluid flow communication with said chamber means, said valve means having opened and closed modes, and means completely closing said valve means in response to said accelerated movement of the press slide ~
to prevent any fluid flow from said chamber means. . .
-6- .
i~ . .
i ( 10~3~ZS
The foregoing objects, and others, wlll ln part be obvious and in part pointed out more fully hereinafter in con~unction with the written description of preferred embodiments of the invention shown in the accompanying drawings in which:
FIGURE 1 is a schematic illustration of a shock dampening system in accordance with the present invention associated with the slide and bed components of a shearing press;
` FIGURE 2 is a graph showing slide displacement and press load curves during the working stroke of a shearing press without shock dampening;
FIGURE 3 is a graph showing slide displacement and press load curves during the work stroke of a shearing ." .' .
: 20 ~- .
' - 6a -lOG39Z5 press having a shock dampening s~stem in accordance with the present invention; and, FIGURE 4 is a schematic illustration of a modifica-tion of the system sho~n in FIGURE 1.
Referring now in greater detail to the drawings wherein the showings are for the purpose of illustrating preferred embodiments of the present invention onl~ and not for the purpose of limiting the same, a hydraulic fluid shock dampening system is schematically illustrated in ; FIGUR~ 1 and in conjunction with a shearing press 10 operable, fo~ example, to cut blanks from metal sheets. The structure and operation of presses of this character are of course well known in the art, and details regarding the structure and operation are not necessary to an understanding of the present invention. It will be sufficient to appreciate that the press has a ~rame 12 providing a press bed 14 and that the frame supports a slide 16 for reciprocation toward and away from bed 14, a suitable drive arrangement being provided to achieve such reciprocation. As is further well known in the shearing press art, bed 14 supports a shearing component 18 and slide 16 supports a shearing component 20 cooperable with component 18 to cut material therebetween during down-ward movement of slide 16 to the bottom dead center position thereof. Cutting takes place, of course, from a point along tne slide stroke above the bottom dead center position at which shearing component 20 engages the material to a second point :;; . , 10ti39Z5 along the slide path ~ust ahead of bottom dead center at which shearing components 18 and 20 cooperatlvely break through the material being cut. As is well known to those skilled in the art of presses, engagement of material to be cut between shearing components 18 and 20 during downward movement of the slide imposes a load on the press through the slide and which load is suddenly released upon breakthrough of the material, whereupon down~ard movement of the slide is accelerated in the direction toward the bottom dead center position thereof. This is of course accompanied by release of the energy stored by loading of the press during the shearing operation.
In accordance with the present invention, a shock dampening system is associated with the slide and frame components of the press to minimize downward displacement of the press slide following breakthrough, thus to minimize ; the release of energy resulting from loading of the press up to the point of breakthrough. The shock dampening system, designated generally by the numeral 22 in FIGURE 1, is a hydraulic system including hydraulic fluid receiving variable volume devices 24 mounted on or supported relative to the press bed for actuation by slide 16 during downward movement thereof toward the bottom dead center position. In the embodiment shown, each variable volume device 24 is in the form of a piston-cylinder assembly including a cylinder 26 supported on the press bed and a piston 28 supported within cylinder 26 for vertical reciprocation relative thereto.
The space in cylinder 26 behind piston 28 defines a fluid receiving chamber 30, and cylinder 26 is provided with a common inlet and outlet passage 32 opening into chamber 30.
Slide 16 carries an actuator pin 34 for each piston, and each pin 34 has its upper end threadedly interengaged wit'n a support collar 36 on the slide so that the pin is vertically adjustable relative to the slide for the purpose set forth hereinafter.
Chambers 30 of variable volume devices 24 are con-nected to a common source of hydraulic fluid under pressure.
~lore particularly, in the embodiment shown in FIGURE 1 a motor-pump unit 38 is adapted to deliver hydraulic fluid under pressure to cha~bers 30 fr~m a source 40 through a flow line system including a flow line 42 and branch lines 44 and 46 connected thereto and to one of the passageways 32 of variable volume devices 24. A one way check valve 48 - prevents backflow to source 40, and a pressure responsive unloading valve 50 is operable at a predetermined pressure between valve 48 and the motor-pump unit to return hydraulic fluid to the source when valve 48 is closed and the pressure between the latter valve and motor-pump unit 38 exceeds the setting of valve 50.
A noramlly open fluid flow sensitive shutoff valve 52 is provided in flow line 42 to control fluid flow through the latter line. Valve 52 includes a restricted passageway 54 permitting restricted fluid flow in the direction between chambers 30 and source ~0 when valve 52 is in the open position illustrated in FIGURE 1. Valve 52 further includes a closed passageway 56 which is adapted to blocX fluid flow through line 42 when valve 52 is in the closed position in which pa~sage 56 would be shifted to the right in FIGURE 1 to a position in ~lignement with flow line 42. Valve 52 is normally biased to the open position such as by a spring 58 g , .
1~39ZS
and is adapted to be biased to the right in FICURE 1 by fluid under pressure from branch lines 44 and 46 acting thereagainst tlrough a feed line 60, as described in greater detail here-inafter. For the purpose set forth hereinafter, a low pressure hydraulic fluid receiving accumulator 62 is connected to flow line 42 between valves 48 and 52, and a high pressure hydraulic fluid receiving accumulator 64 is connected in fluid communi-cation with line 42 and branch lines 44 and 46 between valve 52 and chambers 30 of variable volume devices 24.
Operation of the shock dampening arrangement described above will be best understood by referring to FIGURES 2 and 3 of the drawing together with FIGURE 1. Briefly, FIGURES 2 and 3 are graphs showing slide displacment and press load during movement of the slide through the shearing stroke. FIGURE 2 shows the effect of no shock dampening of the slide, and FIGURE 3 shows the effect of the shock dampening system described above and the effect of prior art shock dampening : systems. In both graphs, the point 1 represents the time during the slide stroke at which, in the system disclosed herein, pins 34 engage pistons 28 during movement of the slide toward the bottom dead center position thereof which is indicated BDC in FIGURES 2 and 3. Point 2 represents the time at which the shearing components engage the material to be severed, and point 3 represents the time at which breakthrough of the material by the shearing components .
occurs. Curve L represents the load imposed on the press during a severing operation, and curve D represents the position of the slide during the severing operation relative to bottom dead center. If the press was not loaded by the interposition of material to be cut between the shearing 10~3g25 components, slide displacement curve D would be arcuate throughout its extent and thus would follow the arcuate portion D' between point 2 and BDC in FIGURE 2 and between points 2 and 4 in FIGURE 3. The significance of point 4 is set forth hereinafter.
- With regard now to the operation of the shock dampening arrangement described hereinabove, the components of the press and hydraulic system are in the positions illustrated in PIGURE
1 prior to a shearing operation. Hydraulic fluid is delivered under pressure from source 40 to chambers 30 through flow line 42, restricted passage 54 of valve 52 and branch lines 44 and 46, and the fluid under pressure in chambers 30 biases pistons 28 upwardly. As slide 16 moves downwardly toward bed 14, pins 34 engage pistons 28 just before shearing components 18 and 20 engage the material therebetween to be severed. The ad~ustability of pins 34 enables setting the pins in this respect. As mentioned above, the material is engaged at point 1 in the graphs of FIGURES 2 and 3 and at this time the slide is located ~-,~
a distance S above BDC. Continued downward movement of slide 16 causes downward movement of pistons 28 in cylinders 26 thus forcing the hydraulic fluid in chambers 30 into branch lines 44 and 46 through cylinder passages 32. This fluid from chambers 30 flows back toward source 40 through restricted passage 54 of valve 52 and, since one way valve 48 is closed against return of fluid to source 40, accumulator 62 receives the back flow fluid - under pressure and stores the latter for return towards chambers 30 as set forth hereinafter. During this movement of the slide toward its bottom dead center position the slide has a normal velocity which is a known factor in connection with a given press and ,:
, .
10~392S
shutoff valve 52 is structured for this normal velocity to produce a minimal pressure drop through restricted passage 54, whereby the opening bias is sufficient to maintain valve 52 open.
Continued downward movement of slide 16 brings shearing components 18 and 20 into engagement with the material there-between, thus initiating the imposition of a losd on the press through the slide. This engagement with the material is re-presented by point 2 in the graphs, and at this time the slide is spaced a distance W above the bottom dead center position thereof. As the shearing components cut the material, pins 34 continue to depress pistons 28 and the loading of the press restrains advancement of the slide and reduces the velocity thereof. Accordingly, the piston displacement is gradual causing a continuance of the foregoing fluid flow from chambers 30 through restricted passage 54 of valve 52 to accumulator 62.
As will be seen from load curve L in the graphs, the press is loaded from zero to a maximum as the shearing components move through the material during the period of slide displacement represented between points 2 and 3. At the same time, it will be seen that the material between the shearing components restrains displacement of the slide in the downward direction towards bottom dead center, as represented by portion D2 of the displacement curve in the graphs.
The shearing components breakthrough the material at point 3 whereby the load is removed from the press and the stored energy of the load is imposed on the slide causing a rapid acceleration of the slide towards its bottom dead center position. In the absence of any shock dampening ~063925 o~ the slide a~ this point, the slide is immediately acceler~ted to bottom dead center, thereby imposing shock on the press and bounce of the slide resulting in the imposition of a series of reverse direction loads on the press as indicated by the portion of load curve L to the right of point 3 in FIGU~E 2.
A shock dampening system in accordance with the present invention advantageously restrains slide displacem~nt toward BDC following breakthrough and minimizes the energy release so as to maintain a load on the~press during completion of the severing operation. In this resp,ect, with reference to FIGURE 1, acceleration of the slide which occurs upon breakthrough is transmitted to pistons 28, thus suddenly accelerating displacement of the pistons in the direction to reduce the volume of chambers 30. This sudden displace-ment increases the velocity of the hydraulic fluid ~lowing from ; chambers 30, whereby valve 52 is actuated through feed line 60 to close the valve and thus positively ~lock fluid flow from chambers 30. Thus, as seen in FIGURE 3, load energy release is stopped at point 5 following breakthrough and the slide ~-is restrained from reaching BDC, as represented by portion ~3 of the slide displacement curve. Accordingl~, a major pro-portion of the load is maintained on the press following breakthrough. From the point of time in normal slide displace-ment at which B~C is reached the press load i5 progressively decreased as a result of movement of the slide drive components which would normally cause upward displacement of the slide from ~DC. At point 4 in the graph of ~IGURE 3, the slide drive components are in slide displacement positions corres-pondin~ to the displacement position in which the slide is held by the piston-cylinder units 24. Thereafter, the slide , 1063~Z5 drive components move the slide up~ar~ly and thc load on the press is reduced to zero.
The load maintained on the press in this rnanner maintains the hydraulic fluid between chambers 30 and valve 5~ under pressure to maintain valve 52 closed. Upon upwa-d movement of slide 16, the fluid pressure in the system biases pistons 28 upwardly to reduce s~stem pressure and thus provide for spring 58 to open valve 52. Thereafter, fluid accumulated under pressure in accumulator 62 is released to flow through L0 restricted passage 54 of valve 52 back into branch lines 44 and 46 and chambers 30 to fully bias pistons 28 to their uppermost positions. Motor-pump unit 38 is operable to replenish any fluid leakage from the system which might occur during operation o~ the press.
High pressure accumulator 64 is a safety device to prevent damage as a result of press overload. If, far example, there is some breaXdown which causes the press slide to impose a high pressure on the hydraulic system between piston-cylinder units 24 and check va}ve 48, accumulator 64 is actuated to receive fluid under such excess pressure.
The embodiment of the present invention illustrated in FIGURE 4 is the same in many xespects as that shown in FIGURE 1 and, accordingly, like numerals are employed in FIGU~ES 1 and 4 to designate li~e components. In the embodi-ment of FIGURE 4, restricted passageway 54 of shutoff valve 52 is in communication with source 40 and piston-cylinder units 24 through flow line 42 and a branch line 66 leading to the valve. Additionally, fluid flow through restricted passage 54 in respon~e to downward movement of pistons 28 prior to sO material brea~through is released by a low pressure ch~ck , , - 14 -1~63g25 valve 68 for flow to a sump or the ]ike 70 leadlng back to source 40. In further comparison of this embodlment with that shown in FIGURE 1, high pressure accumulator 64 in FIGURE 1 is replaced by a pressure responsive relief valve 72 which is operable in response to an undesirably high fluid pressure in the system to dump fluid to a sump or the like 74 for return to source 40. Further, low pressure accumulator 62 in FIGURE 1 is replaced by a low pressure accumulator 76 positioned between motor-pump unit 38 and check -~
valve 48 to accumulate fluid under pressure when shutoff valve 52 is closed to provide sufficient fluid for the system to return pistons 28 to their uppermost positions following a severing operation. It will be appreciated that accumulator 76 works in conjunction with motor-pump unit 38 in replenishing the system in this respect.
Operation of the system shown in FIGURE 4 insofar as blocking fluid flow from chambers 30 of piston-cylinder units 24 is the same as that for the system shown in FIGURE 1.
In this respect, initial downward movement of pistons 28 prior to breakthrough is at the velocity of the press slide, whereby valve 52 remains open and fluid expelled from chambers 30 flows through check valve 68 to sump 70. Upon breakthrough, the sudden acceleration of slide 16 and the resulting velocity increase in the fluid flow closes valve 52 to block further flow of fluid from chambers 30 and thus stop downward displace-ment of the slide. When the slide reaches point 4 in the graph of FIGURE 3, system pressure is reduced whereby valve 52 is biased open and pistons 28 are biased to their upper-~- most positions in preparation for the next severing operation.
It will be appreciated in conjunction with both 10~3925 of the embodiments herein disclosed that the magnitude of the load energy release at point 3 in the graph of FIGUR~ 3 can be controlled toward minimization by using a minimum volume of hydraulic fluid in the piston-cylinder units and flow line~, by using a hydraulic fluid having a high bulk modulus, by using a rapid response flow sensltive shutoff valve, and by various combinations of these control possibilities.
While considerable emphasis has been placed on the specific embodiments herein illustrated and described, it will be readily understood that many modifications will be obvious and suggested upon reading the foregoing description .
and can be made without departing from the principles of the present invention. In this respect, for example, while two piston-cylinder units 24 are illustrated, one or more than two such units can readily be associated with a given press structure to provide the desired slide restraint function ; in response to breakthrough, Further, it will be appreciated that variable volume devices other than piston-cylinder units can be employed and that, in connection with piston-cylinder units, the piston-cylinder relationship can be reversed so that the cylinder is a movable component engaged by the press. Still further, while it i~ preferred to employ a flow sensitive shutoff valve permitting restricted fluid flow therethrough prior to breakthrough of the material being severed, it will be appreciated that other shutoff valve structures could be employed, Moreover, it will be appreci-ated that the shutoff valve could be controlled other than by system fluid. For example, the valve could be solenoid actuated to close at the point of breakthrough. It is only ; 30 necessary in accordance with the present invention that the ~,f 1063gZS
shutoff valve b^ act~lated at the point of acceleration of the slide upon breakthrough to positively block fluid flow from the chambers of the variable volume devices.
As many possible embodiments of the present invention may be made and as many changes may be made in the em~odiments herein illustrated and described, it is to be distinctly understood that the ~oreqoing descriptive matter is to be interpreted merely as illustrative of the present invention and not as a limitation.
Claims (18)
1. In a hydraulic shock dampening system for a shearing press having frame means including bed means and supporting reciprocable slide means and wherein material is severed between cooperable shearing means supported by said bed and slide means, said system including hydraulic fluid receiving variable volume chamber means between said bed means and slide means and con-nected to a source of hydraulic fluid under pressure, said chamber means being operable under compression in response to breakthrough of material being sheared by said shearing means supported by said slide means to restrain the resulting accelerated movement of said slide means, the improvement comprising: shutoff valve means in fluid flow communication with said chamber means, said valve means having opened and closed modes, and means completely closing said valve means in response to said accelerated movement of the press slide to prevent any fluid flow from said chamber means.
2. The improvement according to claim 1, wherein said valve means includes restricted passageway means in communication with said chamber means when said valve means is in said open mode to permit restricted fluid flow from said chamber means prior to said accelerated slide movement.
3. The improvement according to claim 1, wherein said valve means is fluid flow responsive and said means closing said valve means is fluid flowing from said chamber means.
4. The improvement according to claim 3 7 wherein said valve means includes restricted passageway means in communi-cation with said chamber means when said valve means is in said open mode to permit restricted fluid flow from said chamber means prior to said accelerated slide movement.
5. The improvement according to claim 3, wherein said valve means is in fluid flow line means from said source to said chamber means, and fluid pressure relief means in said fluid flow line means between said valve means and chamber means.
6. The improvement according to claim 5, wherein said relief means is fluid pressure responsive relief valve means.
7. The improvement according to claim 5, wherein said relief means is fluid pressure responsive accumulator means.
8. A hydraulic shock dampening system for a shearing press having frame means including bed means and supporting reciprocable slide means and wherein material is severed between cooperable shearing means supported by said bed and slide means, comprising variable volume chamber means between said slide means and frame means and including means dis-placeable to reduce the volume of said chamber means during movement of said slide means toward said bed means to sever material between said shearing means, a source of hydraulic fluid, means to deliver hydraulic fluid from said source to said chamber means under pressure, movement of said slide means being accelerated in the direction of said bed means upon breakthrough of material being sheared, said accelerated slide movement accelerating said displaceable means, and fluid flow actuated shutoff valve means in fluid flow communication with said chamber means and actuated to close in response to acceleration of said displaceable means to prevent fluid flow from said chamber means.
9. The shock dampening system according to claim 8, wherein said shutoff valve means includes flow restriction means permitting restricted fluid flow from said chamber means prior to said acceleration of said displaceable means.
10. The shock dampening system according to claim 8, wherein said means to deliver hydraulic fluid from said source includes flow line means connected to said chamber means, and pressure overload relief means in said flow line means between said source and said chamber means.
11. The shock dampening system according to claim 10, wherein said overload relief means is pressure responsive relief valve means.
12. The shock dampening system according to claim 10, wherein said overload relief means is pressure responsive accumulator means.
13. The shock dampening system according to claim 8, wherein said variable volume chamber means includes cylinder means on said press bed and piston means reciprocable therein and defining said displaceable means.
14. The shock dampening system according to claim 13, wherein said cylinder means includes common inlet and outlet passage means opening thereinto behind said piston means and said means to deliver hydraulic fluid from said source includes flow line means connected to said common passage means, check valve means in said flow line means preventing backflow toward said source, and fluid pressure actuated overload relief means in said flow line means between said check valve means and said passage means.
15. The shock dampening system according to claim 14, wherein said shutoff valve means includes flow restriction means in fluid flow communication with said flow line means between said check valve means and said passage means, said flow re-striction means permitting restricted fluid flow from said chamber means prior to said acceleration of said displaceable means.
16. The shock dampening system according to claim 15, and fluid pressure responsive accumulator means in said flow line means between said shutoff valve means and said check valve means, said accumulator means receiving fluid under pressure in response to flow from said chamber means prior to said acceleration of said displaceable means, said accumulator means being responsive to a pressure less than that of said overload relief means.
17. The shock dampening system according to claim 16, wherein said overload relief means is second fluid pressure responsive accumulator means.
18. A method of suppressing shock in a shearing press having cooperable shearing means and wherein shock is occasioned by breakthrough of the shearing means relative to material being severed, comprising: interposing hydraulic fluid receiving variable volume chamber means between the slide and bed of the press so that fluid under pressure is expelled therefrom as the slide moves toward the bed to perform a shearing operation, stopping fluid flow from the chamber means upon breakthrough of the material being severed, and returning fluid under pressure to said chamber means follow-ing movement of the slide through bottom dead center.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US76598177A | 1977-02-07 | 1977-02-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1063925A true CA1063925A (en) | 1979-10-09 |
Family
ID=25075047
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA293,352A Expired CA1063925A (en) | 1977-02-07 | 1977-12-19 | Shock dampening systems for presses |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS53104487A (en) |
| AU (1) | AU511150B2 (en) |
| CA (1) | CA1063925A (en) |
| DE (1) | DE2804185A1 (en) |
| ES (1) | ES466614A1 (en) |
| FR (1) | FR2379375A1 (en) |
| GB (1) | GB1566992A (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4214496A (en) * | 1978-10-06 | 1980-07-29 | Gulf & Western Manufacturing Company | Shock dampening systems for presses |
| US4339975A (en) * | 1980-10-20 | 1982-07-20 | Gulf & Western Manufacturing Company | Shock dampening system for presses |
| JPH04122415U (en) * | 1991-04-12 | 1992-11-04 | 株式会社小松製作所 | Shearing machine vibration reduction device |
| EP1758697B1 (en) * | 2004-06-02 | 2012-01-25 | Stefan Fellenberg | Method and press for cutting high-strength sheet metal |
| DE102005053350A1 (en) | 2005-11-07 | 2007-05-10 | Schuler Pressen Gmbh & Co. Kg | Press with cutting impact damping |
| DE102007030328A1 (en) * | 2007-06-29 | 2009-01-02 | Helmut Schuster | Damping device for diagonal cutting device that is utilized for cutting e.g. stainless steel bar, has chamber formed between base unit and fluid surface, and outlet with cross-sectional area for outputting fluid during piston axial stroke |
| CN102825833A (en) * | 2012-09-28 | 2012-12-19 | 南通久久液压机械制造有限公司 | Shock absorber of hydraulic machine |
| CN109622850A (en) * | 2018-12-21 | 2019-04-16 | 南通科技职业学院 | A kind of monolithic processor controlled forging machine tool |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1427403C3 (en) * | 1962-02-01 | 1975-04-30 | Horst 4600 Dortmund Schenk | Cutting shock-absorbing counter-pressure system in a press, in particular in a hydraulic press |
| DE1577187C3 (en) * | 1964-12-11 | 1975-08-28 | Horst 4600 Dortmund Schenk | Cutting impact steaming counter pressure system in a hydraulic press |
| DE2221290B2 (en) * | 1972-04-29 | 1976-09-02 | L. Schuler GmbH, 7320 Göppingen | CUTTING IMPACT DAMPER DEVICE FOR MECHANICAL PRESSES |
| DE2512822A1 (en) * | 1975-03-22 | 1976-09-30 | Horst Schenk | Cutting impact damping in presses - has piston cylinder unit arranged so that hydraulic fluid is expelled from cylinder to effect damping |
| DE2653714C2 (en) * | 1976-11-26 | 1978-11-09 | Frieseke & Hoepfner Gmbh, 8520 Erlangen | Cutting shock absorption device for punch presses |
-
1977
- 1977-12-19 CA CA293,352A patent/CA1063925A/en not_active Expired
- 1977-12-22 AU AU31885/77A patent/AU511150B2/en not_active Expired
-
1978
- 1978-01-13 GB GB147478A patent/GB1566992A/en not_active Expired
- 1978-01-26 FR FR7802241A patent/FR2379375A1/en active Granted
- 1978-02-01 DE DE19782804185 patent/DE2804185A1/en not_active Withdrawn
- 1978-02-03 ES ES466614A patent/ES466614A1/en not_active Expired
- 1978-02-07 JP JP1289578A patent/JPS53104487A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| AU3188577A (en) | 1979-06-28 |
| AU511150B2 (en) | 1980-07-31 |
| ES466614A1 (en) | 1978-10-01 |
| DE2804185A1 (en) | 1978-08-10 |
| GB1566992A (en) | 1980-05-08 |
| FR2379375A1 (en) | 1978-09-01 |
| FR2379375B1 (en) | 1983-06-24 |
| JPS5749329B2 (en) | 1982-10-21 |
| JPS53104487A (en) | 1978-09-11 |
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