Turning – Process of turning
Reexamination Certificate
2000-02-07
2001-09-04
Tsai, Henry (Department: 3722)
Turning
Process of turning
C082S124000, C082S126000
Reexamination Certificate
active
06283000
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to bar stock feed mechanisms, and in particular to a bar puller accessory for mounting upon the rotary turret of a numerically controlled lathe, the magnetic bar holder configured to engage and pull bar stock for machining same on demand.
In the preferred embodiment of the present invention, the bar puller has a body having an engaging end and a mounting end, the mounting end configured to be removeably mounted to a station on the rotary turret.
The bar puller is actuated by fluid pressure from liquid coolant flowing from the cooling system of the lathe, the coolant passing through a longitudinal bore in the body of the unit so as to urge a piston, having a high field strength magnet, to migrate within the longitudinal bore towards the engaging end of said bar holder, so as to provide a magnetic field in the vicinity of the engaging end, to selectively engage a bar or other ferrous object in the vicinity of the engaging end of the bar puller.
A spring is provided to urge the piston away from the engaging end of the bar holder, removing the magnetic field from the vicinity of the engaging end, when fluid pressure ceases due to programmed cessation of flow of coolant through the system.
BACKGROUND OF THE INVENTION
The prior art has contemplated a multitude of bar pullers and magnetic holders or the like, although none are believed to contemplate, teach, or otherwise suggest the device of the present invention.
A list of patents which may have some pertinence to the present invention include:
U.S. Pat. No.
Inventor
Date of Issue
2915682
Bower
12/01/1959
3010054
Goudsmit
11/21/1961
3079191
Engelsted et al
02/26/1963
4401960
Uchikune et al
08/30/1983
4924738
Che
05/15/1990
5080380
Nakagawa et al
01/14/1992
5115702
Link
05/26/1992
5165313
Karr
11/24/1992
5845950
Stowe et al
12/08/1998
5960689
Warren
10/05/1999
U.S. Pat. No. 3,079,191 dated Feb. 26, 1963, teaches a “Permanent Magnet Lifting Device” including a housing having first and second ends, the first end configured to engage a support, the second end configured to form the work piece engagement end. The housing has formed therethrough a bore having slidably situated therein, a magnet housed in a piston (in this case, two bores and two pistons), with a magnetic surface facing the second end of the housing. A cap is provided at the second end to form a work piece contact surface. Further provided is means to motivate the piston/magnet arrangement within the bore to and away from the work piece contact surface at the second end of the housing, so as to engage/disengage the work piece.
U.S. Pat. No. 2,915,682 issued 1959, which also includes spring (30) to provide spring bias to the system. Another example may be found in 4,401,960, entitled “Magnet Assembly”. Lastly, U.S. Pat. No. 5,845,950 teaches a “Pneumatically Actuated Magnetic Article Holder” having some relevance to the above patents, but teaching fluid actuation to motivate the magnet means.
The above patents are distinguishable from the present, searched for invention, as they do not teach a bar puller, although it is possible that one or more of the above devices might be able to be modified to perform as such. For other magnetic holders, see U.S. Pat. No. 5,080,380 for a “Magnetic Chuck” assigned to Murata Manufacturing, Inc., teaching multiple pistons in a housing, the pistons forming magnets, which are motivated to move to and from a work piece surface via compressed air. This patent is relevant in that, in addition to the concept of providing a work piece holder utilizing a piston having a magnet which is motivated to and away from the work surface, this patent also teaches the concept of utilizing fluid pressure to accomplish same.
U.S. Pat. Nos. 4,924,738, 5,165,313, and 5,960,689 provide examples of bar puller patents.
GENERAL SUMMARY DISCUSSION OF THE INVENTION
The present invention teaches a bar puller as may be utilized in a computerized, numerically controlled lathe, milling machine or the like, wherein the unit is preferably mounted to a station on the rotary turret of the lathe, the turret generally having a plurality of stations for the mounting of machine tools thereon, which are selectively utilized by rotating the turret so that the chosen station may be positioned for machining the bar, stock, or other work piece held in position by the lathe's collet or spindle chuck.
The bar puller of the present invention comprises a body or housing having first and second ends, the first end comprising a mounting shank configured to engage a support bracket on the rotating turret of the lathe, the second end configured to form the work piece engagement end. It is noted that the mounting shank may vary depending upon the configuration of the tool mount of the lathe, or may be otherwise mounted to the unit.
The housing has formed therethrough an longitudinal bore, such that the first end further includes fluid engagement means for receiving fluid (coolant) under pressure. Further provided in the bore, slidably situated therein, is a magnet housed in a piston such that a magnetic surface is projected towards the second end of the housing.
The piston has a spring bias provided by a spring situated within the longitudinal bore, the spring having first and second ends, the first end communicating with an anchor pin situated within the bore in the vicinity of the first end of the housing, the second end affixed to the piston. The piston further has a clearance relative to the inner walls of the bore to allow the passage of coolant therebetween.
A cap is configured to cover the second end of the longitudinal bore to form the work piece contact surface, the cap having formed therein a fluid escape passage.
In operation, the bar puller relies upon programmed operation of the CNC lathe to direct the actions involving the unit. The bar puller is mounted to a station in the rotary turret, which is selectively positioned by the operating program directing the lathe to rotate into position, and maneuvering same adjacent to the bar stock. The work piece contact surface is selectively provided with a strong magnetic field by applying fluid pressure into the longitudinal bore of the body of the unit through the mounting shank via coolant flow through the first end of the housing and longitudinal bore, the coolant flow providing a hydraulic pressure sufficient to overcome the spring bias and urging the piston and magnet adjacent to the cap at the second end of the longitudinal bore. The strong magnetic field thereby generated at the cap is adequate to grasp and pull bar stock or the like.
When it is desired to disengage the work piece, fluid pressure is relieved, and the spring bias urges the piston and magnet away from the cap, withdrawing the magnetic field, and releasing the work piece. The fluid passageway formed in the cap not only projects cooling fluid upon the work piece during milling or machining, it also prevents the accumulation of metal shavings or the like on the work piece contact surface, or within the longitudinal bore or magnet.
The unit is easily installed and detached from the turret station, as necessary for use in generally repetitive operations.
While the prior art searched contemplated a variety of bar pullers and the like, most bar pullers utilized clamps or the like for mechanically grasping the bar stock.
Past bar pullers utilizing a magnet have tended to accumulate shavings or metal debris, the devices being ineffective in selectively initiating or deactivating the magnetic field. An exception is electromagnets, but these units require a power supply and switching system, and thereby were more complicated, expensive, and less reliable than the present system.
The present invention thereby provides an easily implemented, cost effective and reliable bar puller which requires little in the way of maintenance or servicing, may be utilized to pull a variety of diameter bars with no damage to the bar or other feed stock, and which can be easily removed or installed as is necessary with little i
Joseph T Regard, LTD, plc
Tsai Henry
LandOfFree
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