Draw bar actuator for vertical milling machines

Abstract

An actuator mechanism arranged on a top head portion of a Bridgeport-type vertical milling machine, for controlling intermittent, tool-changing longitudinal movement of a collet-supporting drawbar in that Bridgeport-type vertical milling machine. The actuator mechanism comprises a pressor pin supported on the head portion of the vertical milling machine. The pin is arranged in reversibly abutable contact with the upper end of the drawbar in the machine. A biasing member is arranged to effect movement of the pressor pin against the upper end of the drawbar to effect movement of the drawbar and permit change of a collet and tool thereby.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and advantages of the present invention will become more apparent when viewed in conjunction with the following drawings, in which:

FIG. 1 is a side elevational view, in section, of a Bridgeport type vertical milling machine with the drawbar actuator arrangement shown disposed atop its head;

FIG. 2 is a side elevational view, in section, of an embodiment of the drawbar actuator shown in FIG. 1;

FIG. 3 is a view taken along the lines 3-3 of FIG. 2; and

FIG. 4 is a schematic representation of alternative embodiments of the actuator.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings in detail, and particularly to FIG. 1, there is shown the present invention which comprises a draw bar actuator 10 utilized for example, in a “Bridgeport” type vertical milling machine 12. This type of vertical milling machine 12 includes a generally vertically disposed head 14 which rotatably encloses a vertically arranged spindle 16. The spindle 16 is rotatably driven by motor means 18 connected thereto. The spindle 16 comprises an elongated hollow shaft 20 having a, central bore 22 therethrough. The spindle 16 is supported within the head 14 of the machine 12 by a plurality of bearings 26, 28, 30 and 32. An elongated drawbar 34 is arranged through the central bore 22 of the spindle 16, extending from the uppermost end thereof, to a location adjacent the lowermost end of the spindle 16. The spindle 16 is movable upwardly and downwardly by a rack and pinion arrangement 40 arranged on the side of the head 14. The up and down movement of the spindle. 16 may now be also effected by a servo mechanism, not shown, which may be utilized in a complimentary manner with the quill feed handle attached to the rack and pinion mechanism 40, as shown in my earlier incorporated U.S. Pat. No. 5,846,037.

The upper end of the drawbar 34 preferably may have a threaded portion 42 thereon. A nut 44 is preferably threadedly attached onto the upper end of the drawbar 34, as shown in FIG. 1. A compression spring 46 is arranged between the distal uppermost end of the spindle 16 and the nut 44 to provide a compressive force therebetween. The nut 44 is adjustably disposed on the threaded portion 42 of the drawbar 34 so as to adjust the compression in the spring 46 thereadjacent.

The drawbar actuator 10 is arranged on the top of the head 14, so as to enclose the uppermost end of the drawbar 34 and to provide a controlling relationship therewith. The lower end of the spindle 16 encloses a tool-holding collet 60. The collet 60 is a slender, cylindrically-shaped, elongated member having a first or lower end into which a milling tool 64 is secured. The collet 60 has a gripping head 66 attached to its upper end. The gripping head 66 may be comprised of a generally spherically shaped enlarged engagement portion having neck which connects the enlarged portion to a body of the collet 60.

A coupling member 70 is threadedly attached to the lowermost end of the drawbar 34, as described in my aforementioned '037 U.S. patent. The coupling member 70 comprises a generally cylindrically shaped body having a lower end with a plurality of ball bearing support orifices therearound. The coupling member 70 also includes an outer sleeve. The lowermost end of the sleeve mates snuggly with and is securely wedged into the innermost portion of the collet/tool holding surface at the lower end of the spindle 16. The lower inner housing of the coupling member 70 is longitudinally movable relative to the outer sleeve 72 of the coupling member 70. The controlled relative longitudinal motion between the outer member 72 and the coupling member 70 and the inner housing permits a plurality of balls spaced within the ball socket openings on the inner member to slip radially outwardly thus permitting the generally spherically shaped head on the upper end of the collet 60 to be allowed to slip therepast.

The drawbar actuator 10, represented in a first embodiment in FIGS. 1 and 2, is mounted on the top of the head 14 of the milling machine 10 and is utilized to effectuate the longitudinal movement of the drawbar 34 relative to the spindle 16, so as to permit the collet 60 to be released from the lower end thereof. The drawbar actuator 10 in a first preferred embodiment, comprises a generally spherically shaped housing 80 having a threaded lower end portion 82 which engages a flange 84 on the upper of the head 14. The housing 80 of the actuator 10 in this first preferred embodiment has an upper end 86 with a pivotable handle 88 arranged thereon. An elongated longitudinally movable pressor pin 90 is movable arranged through a mid-housing flange 92 and is in longitudinal alignment with the upper end of the drawbar 34, as represented in FIGS. 1 and 2. The pressor pin 90 has an upper end 92 which is in engagable contact with a mid-portion of the lever arm 88, as represented in FIG. 2. A compression spring 94 is arranged between the flange 92 and the handle 88, so as to provide a biasing resistance to movement of the handle 88 within the upper end of the actuator housing 80. The presspr pin 90, in a further embodiment thereof may be comprised of an attached extension member arranged on the upper end of the drawbar 34.

In a further preferred embodiment, the pressor pin 92 may be pivotably supported at its upper end by the lever 88 at a pivot axis 91 thereof, shown by dashed lines 92′ in FIG. 2.

In operation of the Bridgeport vertical milling machine 12, when it is desired to change a tool 64 at the lower end of the spindle 16, the rotation of that spindle 16 is stopped, the elongated handle 88 is pivoted downwardly within its housing 80, so as to provide a downward force on the pressor pin 90, thus also providing a downward force on the upper end of the drawbar 34. The drawbar 34, thus being pressed downwardly within the spindle 16 and with respect thereto, pushes the collet 60 from its capture within the collet enclosure sleeve 72. The collet 60 with its associated tool 64 therewith may be thus quickly and easily removed by the machine operator, and a new replacement collet 60 with its new tool 64 therein thus being replaced in the lower end of the drawbar 34.

The elongated handle 88 on the drawbar actuator is then released and pivoted upwardly and remains in that position by the biased spring 94 pressing thereagainst and the newly emplaced collet 60 is drawn within the enclosure at the lower end of the spindle and thus brings a new tool into effective working location within that Bridgeport type milling machine 12. Resumption of the milling operation by the Bridgeport type milling machine may thus proceed with its new tool there engaged.

A further embodiment of the drawbar actuator 10 may comprise an empowered pressor pin 90 actuated by a electromechanical, pneumatic or hydraulically operated servo mechanism 100 controlled by a computer or by the machine operator. Such an actuatable biasing mechanism 100 may be thus also be hydraulically, pneumatically or electronically empowered to responsively move the pressor pin 90 downwardly onto the upper end of the drawbar 34 (or hold the upper end of just the drawbar 34 itself) and hold it there for a short period of time, and then release the pressure on the pressor pin 90 and hence also release the pressure on the drawbar 34, permitting it to return to the proper upper “collet-supporting” position.

Claims

1. An actuator mechanism arranged on a top head portion of a Bridgeport-type vertical milling machine, for controlling intermittent, tool-changing longitudinal movement of a collet-supporting drawbar in said Bridgeport-type vertical milling machine, said actuator mechanism comprising: a pressor pin supported on said head portion of said vertical milling machine, said pin arranged in reversibly abutable contact with the upper end of said drawbar; anda biasing member for effecting movement of said pressor pin against said upper end of said drawbar to effect movement of said drawbar and change of a collet and tool thereby.

2. The actuator mechanism as recited in claim 1, wherein said biasing member comprises a pivotable lever swingable on a housing mated on said head portion of said vertical milling machine.

3. The actuator mechanism as recited in claim 2, wherein said lever comprises a manually actuatable lever.

4. The actuator mechanism as recited in claim 2, wherein said lever is actuated by an empowered mechanism.

5. The actuator mechanism as recited in claim 2, wherein said housing encloses an upper portion of said draw bar.

6. The actuator mechanism as recited in claim 2, wherein said housing has a slot in an upper portion thereof, to permit said lever to pivot therethrough.

7. The actuator mechanism as recited in claim 1, wherein said biasing member is resisted by a resistance member arranged thereadjacent.

8. The actuator mechanism as recited in claim 7, wherein said resistance member comprises a spring to push against said biasing member when said biasing member is moved against said pressor pin.

9. A method of changing a tool in a Bridgeport-type vertical milling machine, during a metal working procedure, said method comprising: arranging an actuator mechanism on the upper end of said milling machine, wherein said actuator mechanism is in biasing communication with a collet-engaging draw bar within said milling machine;actuating said actuator mechanism to effect a downward bias on said draw bar to permit the lower end of said draw bar to release a first tool-holding collet engaged within a spindle at a lower end of said milling machine.replacing said released first tool-holding collet with a second tool-holding collet; andresuming said metal working procedure with said second tool-holding collet.

10. The method as recited in claim 9, wherein said actuator comprises a lever biasable against a pressor pin in said mechanism, wherein said pin biases against said upper end of said draw bar.

11. The method as recited in claim 9, wherein said lever is actuated by a servo mechanism to move said draw bar longitudinally for effecting release and engagement of a tool-securing collet at its lower end thereof.

12. The method as recited in claim 9, wherein said lever is manually actuatable by an operator of said machine, to rapidly change tools therefor.

13. An actuator mechanism arranged on a top head portion of a Bridgeport-type vertical milling machine, for controlling intermittent, controlled tool-changing longitudinal movement of a collet-supporting drawbar in said Bridgeport-type vertical milling machine, said actuator mechanism comprising: a vertically displaceable bias member supported on said head portion of said vertical milling machine, said vertically displaceable bias member arranged in reversible communication with the upper end of said drawbar to effect longitudinal movement of said drawbar to effect and permit a change of a collet and tool at the lower end of said drawbar thereby.

14. The actuator mechanism as recited in claim 13, wherein said displaceable bias member comprises a pivotable lever intermittently movable against the upper end of said drawbar, which drawbar supports said tool engaging collet at its lower end thereof.

15. The actuator mechanism as recited in claim 13, wherein said displaceable bias member comprises a servo mechanism arranged in communication with the upper end of said drawbar.