US3524384A - Stroke control for ram type machine - Google Patents

Stroke control for ram type machine Download PDF

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Publication number
US3524384A
US3524384A US720053A US3524384DA US3524384A US 3524384 A US3524384 A US 3524384A US 720053 A US720053 A US 720053A US 3524384D A US3524384D A US 3524384DA US 3524384 A US3524384 A US 3524384A
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United States
Prior art keywords
ram
stroke
valve
contacts
work
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Expired - Lifetime
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US720053A
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English (en)
Inventor
Rolland A Richardson
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Pacific Press and Shear Corp
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Pacific Press and Shear Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
    • B30B15/16—Control arrangements for fluid-driven presses
    • B30B15/18—Control arrangements for fluid-driven presses controlling the reciprocating motion of the ram
    • B30B15/20—Control arrangements for fluid-driven presses controlling the reciprocating motion of the ram controlling the speed of the ram, e.g. the speed of the approach, pressing or return strokes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
    • B30B15/16—Control arrangements for fluid-driven presses
    • B30B15/166—Electrical control arrangements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
    • B30B15/16—Control arrangements for fluid-driven presses
    • B30B15/18—Control arrangements for fluid-driven presses controlling the reciprocating motion of the ram
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
    • F15B21/08—Servomotor systems incorporating electrically operated control means
    • F15B21/087—Control strategy, e.g. with block diagram

Definitions

  • a depth stop adjustably installed on the ram is adapted to engage and actuate a depth limit switch mounted on an adjacent fixed portion of the machine in the path of movement of the depth stop.
  • a back travel stop adjustably installed on the ram is adapted to engage a back travel limit switch similarly mounted on the fixed portion of the machine.
  • FIGURE 1 is a view depicting the hydraulic system ofa ram type machine of the present invention
  • FIGURE 2 is a view depicting the flow passages and manner of operation of a valve assembly employable in the system of FIGURE 1;
  • FIGURE 3 is a view depicting the electrical control system involved in cooperation with the hydraulic system of FIGURE l;and
  • FIGURE 4 is a graph depicting the various stroke control adjustments available with the present invention.
  • the invention is depicted as incorporated in a ram type machine of the press brake type, in which the ram is operated hydraulically, and provision is made for initially advancing the ram at an increased rate of speed, and changing it to the normal pressing speed as the ram approached the work.
  • this type of machine is not basically new, only a brief description of the machine is necessary, and then only the pertinent portions thereof involved in the operation of the present invention.
  • Such machine includes a ram 1 reciprocally mounted for cooperation with a suitable die (not shown).
  • the ram is driven or powered by a pair of hydraulic motors 3 and 5, one at each end of the ram and including a cylinder 7 mounted on the frame of the machine, and a piston 9 coupled to the ram at a proximate point thereof.
  • the hydraulic motors are supplied hydraulically by a pair of pumps 11 and 13.
  • a flow line 15 from each pump is divided into two flow line branches 17 and 19.
  • One branch 17 extends to the upper end of the cylinder of one of the hydraulie motors, and includes a normally closed valve assembly 23 controlled by a normally closed pilot valve 24 which, in turn, is electrically actuated by a solenoid winding 25.
  • this flow line 17 Down stream of the valve assembly, this flow line 17 is adapted to be flow connected to a tank 26 through a normally closed valve assembly 27 controlled by a normally open pilot valve 29 which in turn, is electrically actuated by a solenoid winding 31.
  • the valve assembly 33 just referred to may be of a design enabling a two speed work stroke, namely a work stroke in which the initial portion may be at a greater than normal rate of speed, to be changed to normal or pressing speed as the ram approaches the work.
  • a two speed work stroke namely a work stroke in which the initial portion may be at a greater than normal rate of speed, to be changed to normal or pressing speed as the ram approaches the work.
  • Such valve assembly involves a main flow passageway 39 having a normal input end 41 and a normal discharge end 43,.this passageway being spanned by a main valve 47 which is continually being urged toward its seating position by a valve spring 49.
  • the main valve is formed with a valve stem 51 extending upwardly therefrom and connecting with a piston 53 outside of the main passageway.
  • the main valve is also provided with a valve stem 55 extending downwardly therefrom and similarly connecting with a piston 57 outside of the main passageway.
  • the upper piston is slidable in a cylinder 59 which is hydraulically coupled to the input side of the main flow passageway by a flow connection 61.
  • the piston at the lower end of the downwardly extending valve stem is housed in a cylinder 63 which is flow coupled to the flow passageway, also at the normal input side of the main valve, by a pressure connection 65.
  • the pump pressure will be applied to both pistons simultaneously and if the pistons are of approximately the same area, the pressure against one will substantially nullify the pressure applied to the other, leaving the valve spring 49 free to maintain the main valve in its closed position upon the valve seat, aided by liquid pressure against the limited exposed area of the valve. If the calibration of the valve spring is sufficiently low, such that the pressure applied to the lower piston, is greater than the combined pressure of the spring and liquid pressure on the main valve, the valve will open up on removal of hydraulic pressure against the upper piston.
  • valve assembly Designed into this valve assembly, are features permitting reversal of flow therethrough, should pressure at the output side of the valve assembly develop to a value exceeding that of the pump pressure at the input side, a condition which can develop upon initiating a work stroke of the ram.
  • the normal output side of the main flow passageway is flow coupled to a check valve assembly 71 involving a housing 73, an internal valve seat 75 and a check valve 77 biased to seating position by a valve spring 79 in the housing behind the check valve.
  • the check valve housing is included in and made a part of the pressure connection 65 to the lower piston. Also included in such pressure connection, is a restricted section 81 capable of causing a pressure drop, with flow of liquid therethrough.
  • the branch flow line 19 is adapted to be flow connected to tank through a normally closed valve assembly 85 controlled by a normally open pilot valve 87 which is electrically actuated by a solenoid winding 89.
  • each pump is adapted to be directly flow connected to tank through a normally closed overload relief valve assembly 93 adapted to be opened by a normally open pilot valve 95 which is electrically actuated by a solenoid winding 97.
  • each overload relief valve assembly being a normally open valve, both pumps will be flow connected to tank, thus shunting the hydraulic motors, and the machine under these conditions will be idle.
  • Power is derived from main lines 101, 103 by means of a multiple switch 105, preferably foot operated and involving a pair of switches 107 and 109 sequentially operated through depression ofa foot pedal 1 l].
  • the first switch has a pair of normally closed contacts 113 adapted to open a circuit including a manual switch 115, a normally closed back travel limit switch 117, a pair of normally closed contacts 119, and the coil of a time delay relay 121.
  • timing mechanism 127 the time adjustment of which is controlled by a manually adjustable rheostat 129. While any suitable timing mechanism may be employed, that which is the subject of patent No.3,ll54,725 has proven quite satisfactory.
  • normally open contacts 135 Associated with the normally closed contacts of the first switch, is a pair of normally open contacts 135 which will automatically close following opening of the first pair of contacts, and these normally open contacts are in circuit with a pair of normally closed contacts 137 associated with the "up relay winding 125, and a relay winding 139.
  • the second switch 109 like the first, also includes a pair of normally closed contacts 141, and a pair of normally open contacts 143 to be engaged following opening of the normally closed contacts.
  • the normally closed contacts 141 are connected in circuit with the solenoid winding 89 associated with the valve assembly coupling the return line 19 to tank, while the normally open contacts of this second switch connect through the normally open contacts 147 of a depth limit switch 149 to the back travel limit switch 117.
  • Normally open contacts 143 also control a circuit through a set of normally closed contacts 151 of depth limit switch 149, a pair of normally closed contacts 153 associated with time delay relay 121, to parallel circuits controlling the operation of the solenoid windings 25 which initiate a down work stroke of the ram, and the solenoid windings 97 controlling the operation of the overload relief valve assemblies 93.
  • the down solenoids are connected in circuit through normally closed contacts 155 associated with the time delay relay 121 while the overload relief valve solenoid windings are each connected in circuit'through a normally closed microswitch 157 to open the circuit at either of these points should the ram tilt too far in one direction or the other.
  • the manual switch 115 unless it is desired that the ram shall cycle, will remain open normally. Therefore, the normally closed contacts 113 of the foot switch, will be ineffective.
  • solenoids 89 Normally closed contacts 141 of the foot switch maintain solenoids 89 energized, which in turn block valve assemblies to return flow to tank from return lines 19, thus supporting the ram in position for a down stroke.
  • Relay 139 Upon depressing the foot switch, closing of contacts 135, energizes the relay 139 through the normally closed contacts 137 of the up relay.
  • the relay I39 closes a pair of normally open contacts 161 shunting the switch contacts 135, to effect a holding circuit.
  • Relay 139 has a second pair of normally open contacts 163, which are in circuit with a pair of normally closed contacts 167 of the "up" relay and a timer 169 similar to timer 127. The timer 169 thus becomes energized.
  • each solenoid winding 89 would normally become de-energized to open the proximate valve assembly 85 connecting the lower end of the associated hydraulic motor to tank.
  • the overload relief valve assemblies 93 each will function to block direct flow from the proximate pump to tank.
  • the down' solenoids 25 each will become energized to unblock its associated line 17 to the upper end ofa hydraulic motor.
  • the normally closed contacts 141 of this lower switch are shunted by a circuit including a manual switch in series with a pair of normally closed contacts 177 associated with the rapid advance timer 169.
  • the manual switch 175 With the manual switch 175 closed, opening of the normally closed contacts of the lower switch 109 will be ineffective to de-energize the solenoid windings 89, and accordingly, the valve assembly 85 controlled thereby, will remain closed, while the solenoid windings 97 and 25 will become energized upon closing ofthe lower contacts 143, to respectively close the valve assemblies 93 while opening the valve assemblies 23, to connect each pump to the upper end of one of the hydraulic motors, to initiate a work stroke.
  • valve assemblies 85 With the solenoid windings in their energized condition and causing valve assemblies 85 to block discharge to tank from the lower ends of the hydraulic motors, normal advance of the ram cannot be expected. However, were the valve assemblies 33 open to reverse flow therethrough, hydraulic fluid discharging from a hydraulic motor, could join the output from the proximate pump to supply the upper end of the hydraulic motor being supplied by that pump, and with the pump supply thus supplemented by discharge from such hydraulic motor, a rapid advance of the ram would result, which at some point in the work stroke, could be converted to the normal pressing speed, by opening of the normally closed contacts 177 in the shunt circuit.
  • the normally closed contacts 177 associated with the timer, will open, with the result that the solenoid windings 89 will become de-energized and cause valve assemblies 85 to open and flow connect the lines 19 to tank, which immediately converts the rapid advance speed of the ram to normal pressing speed, for the power liquid to the hydraulic motors no longer includes liquid discharged from such motors.
  • the timing of the speed change point in the work stroke may be correspondingly altered.
  • the ram When the ram reaches the lower limit of its work stroke, it engages the depth limit switch 149, in the course of which it opens the normally closed contacts 151 thereof, and closes its normally open contacts 147.
  • the simultaneous closing of the normally open contacts 147 of the depth limit switch 149 brings about energization of the time delay relay 121, which, in addition to its slow acting normally open contacts 123 and its normally closed fast acting contacts 153, and 155, is also provided with a normally open pair of fast acting contacts 185 paralleling the normally open contacts 143 of the foot switch in series with the normally open contacts 147 of the depth limit switch, whereby, upon energization of the time delay relay, a holding circuit will be established, for it will be apparent that the engagement of the depth limit switch by the ram will only be temporary until the ram begins its return stroke.
  • solenoid windings 97 and 25 remain de-energized for a period longer than that measured by engagement of the depth limit switch by the ram.
  • such period of de-energization should last throughout the return stroke. This is accomplished through the prior energization of the time delay relay, which immediately opens its fast acting normally closed contacts 153 and 155.
  • the up" relay upon becoming energized, opens the normally closed contacts 137 to break the circuit to the relay 139, which in turn will release holding contacts 161, and contacts 163 in the circuit of the timer 169. Further, normally closed contacts 167 associated with the up" relay will open.
  • this relay includes a pair of normally closed contacts 189 adapted to open upon energization of the relay, to de-energize the solenoid windings 31 and open valve assemblies 27, to permit discharge to tank from the upper ends of the hydraulic motors during a return stroke.
  • the overload relief valve assemblies 93 must be closed through energization of the solenoid windings 97, and to accomplish this, the up relay is provided with another pair of normally open contacts 191, which, upon closing in response to energization of the up relay, will connect these solenoid windings 97 across the power supply source.
  • the ram upon closing of the slow acting contacts of the time delay relay and the resulting energization of the "up relay, the ram will begin its return stroke.
  • the back travel timer 127 which is connected in parallel with the up relay, will become energized simultaneously with the up relay, and accordingly, will begin tolling its time period at the instant the ram begins its return stroke.
  • the return stroke may be correspondingly adjusted.
  • the rapid advance timer 169 and circuitry associated therewith may be eliminated, and only the feature involving the back travel timer 127 and its function in controlling the back travel of the ram will be retained.
  • the sliding contacts 191 and 193 of the rheostats will be fixed to a common shaft 195 controlled by a knob 196, while the resistance element 197 of the rheostat associated with the back travel timer, will be fixed as to position, while the resistance element 199 of the rheostat associated with the speed change timer may be rotatably mounted on the shaft, and controlled as to rotatable adjustment on such shaft, by a belt drive from a drive pulley 201 fixed to a shaft 203 carrying a control knob 205.
  • a scale associated with each knob will enable precise adjustments as desired and inasmuch as such adjustments are linear, the scale calibration may be in inches.
  • FIGURE 4 Pictorially represented in FIGURE 4 are the various stroke adjustments available under the present invention.
  • the vertical axis represents stroke distance in terms of inches, while the horizontal axis is marked off in terms of seconds involved in ram travel.
  • the change can be effected by adjustment of the knob 196 which provides simultaneous adjustment of both rheostats.
  • the magnitude of the resistance 199 in the rheostat associated with the advance stroke timer may be such as to cause the point of change over to occur earlier or later in the stroke or approximately remain as it was.
  • the new work stroke will accordingly start one inch closer to the work and follow the broken line 217 of FIGURE 4.
  • An adjustment of the other control knob 205 which serves to adjust but the one rheostat, may shift the point of speed change up or down with respect to the work, depending on the direction of adjustment. If the adjustment is made to accommodate work of a thicker character, the point of change over from one speed to another should occur earlier in the stroke as depicted by the line 219 with respect to the line 221 representing a prior setting.
  • a machine having a reciprocal ram, means for reciprocating said ram to produce a work stroke for operating on work and a return stroke, means for predetermining the end of travel of said ram on a work stroke, and timing means responsive to the arrival of said ram at the end of its work stroke for determining the duration of its travel on its return stroke.
  • timing means being adjustable to alter the length of the return stroke.
  • a machine having a reciprocal ram, means for reciprocating said ram to produce a work stroke for operation on work and a return stroke, means for predetermining the end of travel of said ram during a Work stroke, means, during a work stroke, for driving said rarn at a rapid rate during an initial portion of said stroke and the final portion ofsaid stroke at slower rate, and means for adjusting the time of change from said rapid rate to said slower rate.
  • a machine in accordance with Claim 3 characterized by said means for adjusting the point of change as including adjustable timing means energized at the start of a work stroke for determining the time of change in the rate of travel of said ram during a work stroke.
  • a machine in accordance with Claim 1 characterized by means for adjustably dividing the work stroke into an initial portion at a fast rate of speed and a final portion at a slower speed.
  • a machine in accordance with Claim 5 characterized by said return stroke timing means including an adjustable rheostat, and said work stroke dividing means as including a timing means energized at the start of a work stroke for determining the point of change in the work stroke with said latter timing means including an adjustable rheostat.
  • a machine in accordance with Claim 2 characterized by means for preadjusting the end of travel of said ram on a work stroke, and said timing means being responsive to arrival of said ram at the end of its work stroke, regardless of such preadjustment.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Presses (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Bending Of Plates, Rods, And Pipes (AREA)
US720053A 1968-04-10 1968-04-10 Stroke control for ram type machine Expired - Lifetime US3524384A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US72005368A 1968-04-10 1968-04-10

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US3524384A true US3524384A (en) 1970-08-18

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US (1) US3524384A ( )
JP (1) JPS564763B1 ( )
BE (1) BE723395A ( )
GB (2) GB1246331A ( )

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2076324B (en) * 1980-05-26 1985-06-19 Amada Co Ltd Hydraulic presses
GB2153275A (en) * 1984-01-31 1985-08-21 Blackspur Engineering Limited Compaction of spent nuclear fuel cans
JPS611920A (ja) * 1984-06-13 1986-01-07 Matsushita Electric Ind Co Ltd 燃焼器具の制御装置
JPS611918A (ja) * 1984-06-13 1986-01-07 Matsushita Electric Ind Co Ltd 燃焼器具の制御装置
JPS6153670U ( ) * 1984-09-12 1986-04-11
JPS6224268U ( ) * 1985-07-25 1987-02-14
JPS62172110A (ja) * 1986-01-24 1987-07-29 Matsushita Electric Ind Co Ltd 温風暖房機の制御装置
CN107605870B (zh) * 2017-10-20 2024-06-25 江苏高德液压机械有限公司 带阶梯压缩式推料装置的箱式剪切机
CN110482084B (zh) * 2019-08-20 2021-11-19 长沙中联重科环境产业有限公司 垃圾压实器

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BE723395A ( ) 1969-04-16
GB1246332A (en) 1971-09-15
GB1246331A (en) 1971-09-15
JPS564763B1 ( ) 1981-01-31

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