US3336022A - Powered work-clamping devices - Google Patents

Powered work-clamping devices Download PDF

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Publication number
US3336022A
US3336022A US357511A US35751164A US3336022A US 3336022 A US3336022 A US 3336022A US 357511 A US357511 A US 357511A US 35751164 A US35751164 A US 35751164A US 3336022 A US3336022 A US 3336022A
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United States
Prior art keywords
ram
movement
clamping
pressure
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 - Lifetime
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US357511A
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English (en)
Inventor
Tridgell Cyril William
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Power Jacks Ltd
Original Assignee
Power Jacks Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Power Jacks Ltd filed Critical Power Jacks Ltd
Application granted granted Critical
Publication of US3336022A publication Critical patent/US3336022A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
    • B25B5/00—Clamps
    • B25B5/06—Arrangements for positively actuating jaws
    • B25B5/061—Arrangements for positively actuating jaws with fluid drive
    • B25B5/064—Arrangements for positively actuating jaws with fluid drive with clamping means pivoting around an axis perpendicular to the pressing direction

Definitions

  • This invention relates to powered work-clamping devices, such as are now frequently used on machine tools to hold a workpiece on to a table or jig while some mechanical operation, such as milling, drilling or grinding, is effected.
  • the invention relates particularly to powered workclamping devices of the kind, hereinafter termed the kind referred to, in which the clamp is actuated by a fluid under pressure and has, in addition to the clamping movement, a work-clearing movement, such as a swinging movement, in a direction different from the clamping movement, both movements being actuated from the same source of fluid pressure.
  • One of the problems associated with such work-clamping devices is to arrange for the two movements to operate in a particular sequence so that for clamping it is ensured that the clamp shall move fully from its workclearance position into its extended work-clamping position before the clamping movement commences; and equally for unclamping so that the clamp is fully lifted or otherwise retracted before the work-clearing movement of the clamp commences.
  • This can be, and is, easily effected, where the movements are spring-loaded for return, by differential spring loading of such movements and by biasing the clamping movement by a control valve.
  • bias loaded valve however introduces further problems in that, since time saving is an important factor, and since the work-clearing movement has some inherent inertia, the quicker the work-clearing movement the heavier must be the control valve bias loading in order to prevent premature clamping movement being caused by the pressures necessary to provide the acceleration against such inertia.
  • Any bias loading of the valve is in efliect a bias loading of the ram chamber pressure, as such loading is subtracted from the available clamping pressure so that any such arrangement is necessarily a compromise to set off increased speed of movement against loss of clamping power.
  • the object of the present invention is to provide a powered Work-clamping device having valve biased control with its known simplicity and advantages, but without the disadvantages aforesaid.
  • a powered work-clamping device of the kind referred to having a hydraulic bias control valve is characterised by means responsive to the working movement of the clamp, so arranged as to remove the bias loading of the ram chamber pressure during an initial clamping movement and to restore the bias pressure loading during a final unclamping movement, whereby the full hydraulic pressure in the system is available for clamping without dilferential loss from such loading.
  • FIG. 1 is a side elevation
  • FIG. 2 is a plan of one example of a powered workclamping device made in accordance with the present invention.
  • FIG. 3 is a section on line 33 of FIG. 2.
  • FIG. 4 is a section on line 44 of FIG. 1.
  • FIG. 5 is a fragmentary section on line 55 of FIG. 4.
  • the powered work-clamping device comprises a base 10 having a pair of lugs 11 and 12 by which it is adapted to be bolted to a work table, the base being formed with upstanding bosses 13 and 14.
  • a column 15 with head 15a located in a recess in the under side of the base.
  • a clamping lever 17 fitted with a return spring 18 and having at one end an adjustable and renewable clamping anvil 19. Relatively inclined to such clamping lever the column 15 is formed with a notch 20 (see in FIGS.
  • a return torque spring 25 is housed in the boss 13 around the column and has one end located at 25a in such boss and the other end similarly located in a cover ring 26 adapted to be secured to the column by a socket-headed screw 27 and complementary locating socket 27a in the side of the column.
  • a spring cover 28 enclosing concentric return springs 29, 30 both engaging a common collar 31 abutting against a shoulder of a rain piston 32 the upper end 32a of which extends through such cover to engage the rear end of the clamping lever 17.
  • the ram piston 32 is recessed at its lower end to carry a bias control valve 33 loaded by a spring 34 and retained by a spring ring 35.
  • the valve 33 has a conical nose portion 33a adapted to seat as shown in FIG. 1 to close the end of a passage 36 communicating with the hydraulic space behind the plunger 21.
  • a junction nipple 37 enables a. hydraulic power line to be connected to such hydraulic space.
  • a pressure release valve 38 with loading spring 39 is located in the bias control valve 33 and a release passage 40 therefrom leads through the nose of the valve 33.
  • a clearance distance X exists between the retaining ring 35 and a shoulder at the lower end of the valve 33 surrounding the conical nose of such valve.
  • the clamping ram 32 and valve 33 In operation, with no fluid pressure present, the clamping ram 32 and valve 33 will be in the position shown in FIG. 3 but for convenience the clamping arm 17 and swinging ram 21 are shown moved into position by an initial hydraulic pressure insufficient to open the valve 33 in readiness for work clamping.
  • the valve 33 In order to swing the clamping lever from its work-clearing position to the work clamping position as quickly as possible the valve 33 must be loaded for example to 1000 p.s.i. for use with an available fluid pressure up to 12.00 p.s.i.
  • the pressures in the ram chamber and in the passage 36 Will not normally reach the figure of 1000 p.s.i.
  • the swinging action of the lever is reversible so as to move clockwise or anti-clockwise and this change may be eifected by releasing the screw 27, turning the cover ring 26 until the torque spring is loaded in the other direction and then re-fixing the screw.
  • the plunger 21 requires turning on its axis through 180 degrees complementary to the change of direction of the slot 20 in the column.
  • the invention is not limited to the example above-described in which the bias loading of the valve is itself effectively removed by moving the valve beyond the effective range of movement of the loading spring.
  • the movement of the ram could operate to open and close a by-pass to the ram cylinder from the passage 36.
  • a fluid-actuated swing clamp comprising, a pivotally mounted clamping arm, a ram for moving the arm to a work-clamping position, said ram having a pressure chamber, a hydraulic bias control valve for the hydraulic fluid pressure for the ram, means responsive to the working movement of the arm to remove the bias loading of the ram pressure chamber during an initial clamping movement of the arm, said means being eifective to restore the bias pressure loading during a final unclamping movement of the arm, whereby full hydraulic pressure in the system is available for clamping without differential loss from such unloading, said control valve being movable relative to its seat with the movement of the ram being such as to be unseated and reseated respectively with the initial or engaging movement and final return movement of the ram, the control valve being normally mounted on and coaxial with the ram with limited biasloaded relative movement, a leak-away by-pass in the control valve fitted with a non-return valve and releasing residual pressure in the ram cylinder after the bias-valve has been reseated.
  • a fluid-actuated swing clamp comprising, a base, a column rotatively mounted in the base, a clamp arm pivotally mounted on the column, a swing ram arranged to turn the column from a clearance position for the clamp to working position, spring means for returning the column with the clamp to the clearance position, a clamping ram adapted to engage the clamp arm at its rear end to provide clamping pressure on work engaged by the arm, return spring means for the clamping arm, a connecting passage permanently connecting the pressure chambers of the two rams, a bias valve of substantially smaller seating area than the swing ram carried by the clamping ram and adapted to close the connecting passage when the clamping ram is in its returned position, spring means for loading said bias valve, and means on the clamping ram engageable with the valve to withdraw the valve out of reach of the connecting passage after a small initial movement of the clamping ram, the spring for the valve being of such strength as to provide resistance to valve opening less than the maximum available pressure but greater than that required to overcome the swing return springs, and the swing in

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Jigs For Machine Tools (AREA)
  • Clamps And Clips (AREA)
US357511A 1963-04-04 1964-04-06 Powered work-clamping devices Expired - Lifetime US3336022A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1334063 1963-04-04

Publications (1)

Publication Number Publication Date
US3336022A true US3336022A (en) 1967-08-15

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Family Applications (1)

Application Number Title Priority Date Filing Date
US357511A Expired - Lifetime US3336022A (en) 1963-04-04 1964-04-06 Powered work-clamping devices

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US (1) US3336022A (enrdf_load_stackoverflow)
GB (1) GB1054363A (enrdf_load_stackoverflow)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3554529A (en) * 1968-06-07 1971-01-12 Tomco Inc Retractable and swingable clamps
US3700227A (en) * 1970-12-09 1972-10-24 Applied Power Ind Inc Traversing workholding clamp
US3724836A (en) * 1971-07-12 1973-04-03 Dover Corp Power operated swing clamp
US3967817A (en) * 1974-07-11 1976-07-06 Owatonna Tool Company Swing clamp
US4538797A (en) * 1983-07-08 1985-09-03 Clearing, A Division Of U.S. Industries, Inc. Adjustable hydraulic die clamp
US4721293A (en) * 1986-08-12 1988-01-26 Jergens, Inc. Self-locking clamping device
US5501435A (en) * 1992-07-16 1996-03-26 Monteiro; Luciano T. S. Mechanical cam clamp

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4829489U (enrdf_load_stackoverflow) * 1971-08-13 1973-04-11
JPS533232Y2 (enrdf_load_stackoverflow) * 1973-08-31 1978-01-27
JPS5610498Y2 (enrdf_load_stackoverflow) * 1976-06-16 1981-03-10
JP3667870B2 (ja) * 1996-04-16 2005-07-06 株式会社コスメック 流体圧シリンダ装置

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2335917A (en) * 1941-06-05 1943-12-07 Broom & Wade Ltd Fluid-operated press
US2616259A (en) * 1947-07-15 1952-11-04 Gerotor May Corp Hydraulic system, including multiple motors and controls therefor
US2908205A (en) * 1957-05-24 1959-10-13 Lodding Inc Work clamp having a combined rectilinear and pivotal motion
US2967464A (en) * 1958-08-30 1961-01-10 Commissariat Energie Atomique Clamps
US3173673A (en) * 1962-03-06 1965-03-16 Power Jacks Ltd Powered work-clamping device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2335917A (en) * 1941-06-05 1943-12-07 Broom & Wade Ltd Fluid-operated press
US2616259A (en) * 1947-07-15 1952-11-04 Gerotor May Corp Hydraulic system, including multiple motors and controls therefor
US2908205A (en) * 1957-05-24 1959-10-13 Lodding Inc Work clamp having a combined rectilinear and pivotal motion
US2967464A (en) * 1958-08-30 1961-01-10 Commissariat Energie Atomique Clamps
US3173673A (en) * 1962-03-06 1965-03-16 Power Jacks Ltd Powered work-clamping device

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3554529A (en) * 1968-06-07 1971-01-12 Tomco Inc Retractable and swingable clamps
US3700227A (en) * 1970-12-09 1972-10-24 Applied Power Ind Inc Traversing workholding clamp
US3724836A (en) * 1971-07-12 1973-04-03 Dover Corp Power operated swing clamp
US3967817A (en) * 1974-07-11 1976-07-06 Owatonna Tool Company Swing clamp
US4538797A (en) * 1983-07-08 1985-09-03 Clearing, A Division Of U.S. Industries, Inc. Adjustable hydraulic die clamp
US4721293A (en) * 1986-08-12 1988-01-26 Jergens, Inc. Self-locking clamping device
DE3723494A1 (de) * 1986-08-12 1988-02-25 Jergens Inc Selbsthemmende spannvorrichtung
DE3723494C2 (de) * 1986-08-12 1998-07-23 Jergens Inc Spannvorrichtung
US5501435A (en) * 1992-07-16 1996-03-26 Monteiro; Luciano T. S. Mechanical cam clamp

Also Published As

Publication number Publication date
DE1502900A1 (de) 1969-08-14
GB1054363A (enrdf_load_stackoverflow) 1900-01-01

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