Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
  • B23Q16/00—Equipment for precise positioning of tool or work into particular locations not otherwise provided for
  • B23Q16/001—Stops, cams, or holders therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
  • B23Q1/00—Members which are comprised in the general build-up of a form of machine, particularly relatively large fixed members
  • B23Q1/25—Movable or adjustable work or tool supports
  • B23Q1/26—Movable or adjustable work or tool supports characterised by constructional features relating to the co-operation of relatively movable members; Means for preventing relative movement of such members
  • B23Q1/38—Movable or adjustable work or tool supports characterised by constructional features relating to the co-operation of relatively movable members; Means for preventing relative movement of such members using fluid bearings or fluid cushion supports
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
  • B23Q7/00—Arrangements for handling work specially combined with or arranged in, or specially adapted for use in connection with, machine tools, e.g. for conveying, loading, positioning, discharging, sorting
  • B23Q7/14—Arrangements for handling work specially combined with or arranged in, or specially adapted for use in connection with, machine tools, e.g. for conveying, loading, positioning, discharging, sorting co-ordinated in production lines
  • B23Q7/1426—Arrangements for handling work specially combined with or arranged in, or specially adapted for use in connection with, machine tools, e.g. for conveying, loading, positioning, discharging, sorting co-ordinated in production lines with work holders not rigidly fixed to the transport devices

Definitions

• the present invention relates to means for locating a workpiece fixture on a table during movement thereof from one machining position to another and in particular to a dual centering pin apparatus which selectively engages one or more slots and openings on the downwardly facing surface of the fixture so as to provide controlled translation and rotation thereof.
• the table may be provided with a main pivot pin which projects upwardly from the table surface.
• the pin may be receivable in a socket in the bottom of the fixture in which case the fixture is constrained to move circularly on the table.
• the socket may be replaced by a slot so that the fixture is not only rotatable on the bed but is translatable thereon in various desired directions.
• Cooperating elements of retractable pin and socket locating devices on the fixture and table provide for location of the fixture in predetermined positions on the table. Clamps are also provided to clamp the fixture in the located ' positions on the table during machining.
• Another problem is that of accurately stopping the workpiece at the desired position for subsequent engagement of the locating pins and sockets.
• the operator must therefore search for the desired position through repeated trial and error thereby resulting in a loss of productive machining time.
• the fixture is provided with a pair of crossed slots for dual translation, it is difficult for the operator to determine when the centering pin is located at the intersection of the two slots so that movement from one slot to the other can be accomplished.
• Accurately located rotation centers at various locations within the slots is also desirable for multiple machining operations.
• the present invention overcomes the disadvantages of the prior art by providing a dual centering pin received within the table and comprising an outer pin which is engageable with the fixture slots, an inner pin received within the outer pin, and means for causing the inner pin to extend upwardly out of the outer pin so as to engage holes in the slots.
• the workpiece fixture When the inner pin is retracted, the workpiece fixture is translatable on the table in engagement with the outer pin and when the inner pin is extended and received within one of the fixture holes, the fixture may be rotated thereabout to the desired position.
• the outer pin may be slidably received in the table and in this case sensing means are provided to prevent the supplying of pressurized air between the fixture and table when the outer pin is depressed, as in the case where the fixture is lowered on the table with the slot out of alignment with the centering pin. If air pressure were applied without the fixture positively engaged by the centering pin, it could slide off the table and cause injury to the operator or damage to the workpiece or machine.
• the present invention is particularly adapted for use in apparatus for supporting a work member in a machine tool for machining thereof having a table with a horizontal upper surface adapted to support a workpiece fixture thereon and means for supplying fluid under pressure between the table and fixture. It comprises an outer pin mounted within the table and projecting above the table upper surface, an inner pin being received within the outer pin for movement along a direction generally normal to the table surface, and means for selectively causing the inner pin to project above the outer pin at a first vertical position and alternatively for causing the inner pin to retract to a second vertical position below the first vertical position.
• a safety feature comprising means for interrupting the supply of fluid under pressure between the table and workpiece fixture supported thereon when the outer pin is depressed below a given vertical height relative to the table surface.
• the method according to the present invention relates to locating a workpiece fixture having a downwardly facing bottom surface, a slot in the bottom surface and a hole in the slot, in a machine tool, for example, having a table with an upwardly facing upper surface for supporting the fixture during machining of the workpiece and a first pin extending upwardly out of the table surface.
• the method comprises: supporting a fixture on the table with the table and fixture surfaces in facing relationship and with pin received in the slot, supplying a fluid under pressure between the fixture and table surfaces to provide substantially friction free support of the fixture on the table, causing a second pin having a smaller diameter than the first pin to project upwardly out of the first pin and urge against the fixture slot, moving the fixture on the table such that the slot slides over the first pin until the second pin engages the hole in the fixture, rotating the fixture about the second pin to a predetermined position on the table, and causing at least one pair of locating elements on the table and fixture surfaces to interengage so as to lock the fixture in the predetermined position on the table.
• Another object of the present invention is to provide a dual centering pin apparatus wherein the supply of pneumatic pressure between the fixture and table is blocked when the centering pin and fixture are not interengaged for controlled horizontal movement.
• a further object of the present invention is to provide a dual centering pin which enables rapid and accurate repositioning of the workpiece from one machining position to another.
• Another object of the present invention is to provide a dual centering pin which may be easily incorporated into existing air float machine tool tables.
• Figure 1 is a perspective view of a machine tool incorporating the centering pin of the present invention
• Figure 2 is a top plan view of the table of Figure 1 showing the workpiece fixture in two different positions;
• Figure 3 is a top plan view of the table shown in Figure 1;
• Figure 4 is a bottom plan view of the workpiece fixture;
• Figure 5 is a sectional view of one of the valved connections leading from a passage in the table to the surface on which the workpiece fixture is supported;
• Figure 6 is a sectional view of one of the locating pins shown engaged with a corresponding socket in the lower surface of the workpiece fixture;
• Figure 7 is a schematic of the hydraulic system according to the invention.
• Figure 8 is an enlarged plan view of the centering pin
• Figure 9 is an enlarged sectional view of the centering pin in its fully extended position.
• Figure 10 is an enlarged sectional view of the centering pin which has been depressed by the workpiece fixture.
• Figure 1 is a perspective view of a machine tool having, a bed 20 supported on ways 22 and 24 and a working tool 26 , which may be a boring tool, milling tool or the like according to well known practice in the machine tool art.
• a table or plate 28 is fixedly secured to bed 20 and includes an upper surface 30 on which is supported a workpiece fixture 32 having a workpiece 34 mounted thereon.
• Table 28 is provided with a plurality of fluid passage ways 36 ( Figure 5) which are connected via a control valve 37 ( Figure 7) with a supply of fluid under pressure.
• the fluid is preferably air, but could conceivably comprise other fluid media.
• Passageways 36 extend upwardly through table 28 and communicate with openings 38 in the surface
• valve body 40 which may be threaded into passageway 36 and the top of which is disposed slightly below the level of table surface 30.
• Valve body 40 is tubular and has captured therein a valve ball 42 which projects slightly above the surface 30 of table 28 as shown in Figure 5.
• a spring 44 urges ball 42 into its upper closed position in which it contacts circular valve seat 46.
• table 28 includes a plurality of locating pins 50 which serve to lock the fixture in various predetermined positions.
• the locating pins 50 are located in precise positions on table 28 with reference to tool 26.
• These pins 50 are engageable with sockets 52 in the bottom surface 48 of fixture 32 and which are also accurately located within fixture 32 with reference to the location of pins 50.
• Table 28 is provided with bores 54 each of which at the upper end thereof has an elongated bushing 56.
• Pin 58 having a tapered upper end 60 adapted for seating in the corresponding tapered bushing 62 in socket 52, is slidably received in bushing 56.
• pin 58 is connected to a double acting piston 64 biased upwardly by spring 66 to the position shown in Figure 6.
• Each piston 64 has an upwardly facing fluid surface 68 adapted to be acted on by fluid from passageway 70 to drive the piston 64 and pin 58 downwardly until the upper end 60 of pin 58 is below the upper surface 30 of table 28.
• a supply of fluid pressure to the downwardly facing surface 72 from passageway 74 will drive piston 64 upwardly to effect firm engagement of the tapered end 60 with bushing 62.
• the lower end of bore 76 is closed by a cover plate 78.
• table 28 is provided with a plurality of locating pins 50 so that a number of successive machining positions for workpiece 34 and fixture 32 may be realized.
• pin 58 By supplying air under pressure to the upper side 68 of piston 64, pin 58 will be moved downwardly out of bushing 62. If fluid under pressure is then introduced between fixture 32 and table 28, fixture 32 may be moved to the desired position. With fixture 32 in this position, pneumatic pressure is vented from passageway 70 and pin
• the centering pin 80 according to the present inven tion is shown in detail in Figures 8, 9 and: 10. It comprises a cylinder 82 which is received within bore 84 in table 28 and secured thereto by means of screws 86 and 88, a generally tubular outer pin 90 reciprocally received within cylinder 82, and an inner pin 92 reciprocally received within outer pin 90 and cylinder 82 and having a flanged piston portion 94 at its lower end. O-rings 96 and 98 seal cylinder 82 against bore 84 and seal 100 seals piston 94 against cylinder 82. A coil spring 102 is positioned around inner pin 92 and, when compressed, urges piston 94 and therefore pin 92 downwardly and outer pin 90 upwardly.
• outer pin 90 The upward displacement of outer pin 90 is limited by shoulder 104 coming into contact with screw 106 and ring 134.
• Pressurized fluid either a hydraulic fluid or air, is admitted to the working chamber 108 of cylinder 82 through fitting 110.
• the lower surface 48 of fixture 32 is provided with a pair of intersecting slots 112 and 114 which terminate short of the edges of fixture 32, and a plurality of holes 116, 118, 120, 122 and 124 in slots 112 and 114.
• holes 116 through 124 depends upon the particular machining requirements, it is generally preferable that at least one hole 124 be located at the intersection of the slots 112 and 114.
• fixture 32 may be translated along one of its slots 112 or 114, which is in engagement with outer pin 90. It should be noted that even though inner pin 92 may be retracted as by interrupting the supply of fluid under pressure to chamber 108, outer pin 90 will remain in fully extended position unless physically depressed by an external force, such as the lower surface 48 of fixture 32.
• a safety feature which interrupts the supply of pressurized fluid between fixture 32 and table 28 when outer pin 90 is depressed, is provided.
• it comprises: an electrically conductive plunger 126 reciprocally received within a bore 128 in outer pin 90 and urged upwardly by compressed spring 130 retained within bore 128 by plug 132, an electrically non-conductive ring 134 secured to table 28 by screw 136, a metal contact plug 138 received within ring 134 and connected to an insulated electrical wire 140.
• FIG. 7 A simplified representation of the hydraulic and electric circuits in connection with the safety interlock described above is shown in Figure 7.
• a source of fluid under pressure is supplied through conduits 146 and 148 to the fluid inlets of valves 150, 152 and 154.
• Valves 150 and 152 are three-position valves and operable for reversibly connecting the fluid inlet to one or the.
• Valve 150 has one service line connected to the upwardly facing sides of a pair of locating pin ac tuating pistons 156 and 158 and the other service line connected to the downwardly facing side of the pistons 156 and 158.
• valve 152 has one service line connected to the upwardly facing sides of pistons 160 and 162 for the locating pins 50 and the other service conduit connected to the downwardly facing sides of the pistons 160 and 162.
• valve 154 is normally held in position to supply pressure to conduit 168 by spring 170 but will move into position to exhaust conduit 168 when the pressure in pilot cylinder 156 reaches a predetermined amount.
• valves 150 and 152 are actuated to drive the locating pin 50 upwardly into locating position, after the pins 50 become seated, the pressure built up on the underneath sides of the pistons 156 through 162 will cause valve 154 to shift to interrupt the supply to the fluid cushion for fixture 32.
• the sequence of steps could be entirely under the control of manual valves, if so desired.
• Centering pin 80 is supplied with fluid pressure through conduit 172 under the control of valve 174.
• Wire 140 is connected to a ground sensing device 176 which in turn is connected to solenoid valve 178.
• Ground sensing device 176 is adapted to provide a first output when wire 140 is isolated from electrical ground and a second electrical output when wire 140 is connected to ground.
• An exemplary detector is the Minster Micro-current Detector Unit Bul-010-6056 described in technical bulletin No. 105 of The Minster Machine Company, Minster, Ohio, U.S.A.
• Solenoid valve 178 is is fluid communication with pilot cylinder 166 through bellows selector valve 165.
• ground sensing device 176 senses this condition and causes solenoid valve
• the fixture 32 is accurately located in each desired machining position by means of locating pins 50 and sockets 62. If desired, only one pair of locating pins and sockets 50, 62 need be actuated because centering pins 90 and/or 92 can contribute to locating the fixture 32 and locking it against translation and rotation. While this invention has been described as having a preferred design, it will be understood that it is capable of further modification. This application is, therefore, intended to cover any variations, uses, or adaptations of the invention following the general principles thereof andincluding such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains, and as may be applied to the essential features hereinbefore set forth and fall within the limits of the appended claims.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Machine Tool Units (AREA)
• Jigs For Machine Tools (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=25270568

Family Applications (1)

Country Status (4)

Families Citing this family (8)

Family Cites Families (8)

• 1978
  • 1978-09-20 WO PCT/US1978/000086 patent/WO1979000156A1/en unknown
  • 1978-09-21 IT IT51185/78A patent/IT1105979B/it active
  • 1978-09-22 JP JP11737278A patent/JPS5457282A/ja active Pending
• 1979
  • 1979-04-09 EP EP78900125A patent/EP0006914A1/de not_active Withdrawn

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events