Turning – Process of turning
Reexamination Certificate
2000-09-08
2003-05-06
Tsai, Henry W. H. (Department: 3722)
Turning
Process of turning
C082S124000, C082S118000, C082S127000
Reexamination Certificate
active
06557443
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates generally to an automatic feeder for feeding bars of raw material, i.e., bar stock to a machining tool. More particularly it relates to an automatic feeder for feeding bars to a machining center whether the bar stock is vertically oriented or horizontally oriented and for gripping and holding the bar stock during machining thereof. The present invention also provides for control interfacing of a bar stock feeding and holding mechanism with the control system of an automated machining center, such as a CNC machine either directly or by means of a sequencer system, to enable controlled actuation of the bar stock feeder and holding mechanism by the programmable control system of the machining center and to thus permit sequential machining of multiple parts from the multiple bar stock sections being supported for machining by the machining center.
2. Description of the Prior Art
When processing a plurality of raw material bars or bar stock with an automated programmable machining center, such as a CNC mill, a machine, operator in charge of the machining process must mount each of the sections of bar stock individually for processing by the machine. In many cases the machine operator must position each bar for machining after a preceding part has been completed and cut from the bar. This means that a machine operator must be attending the machine very regularly in order to machine a number of parts from a group of bars. Otherwise the mill or other machine will stand idle for significant periods of time and the bars will not be timely machined and the productive capacity of the machine will not be fully utilized. Many machined parts, require a number of different tool configurations. Since each part is individually machined from the bar stock, the number of tool changes required to make a chosen number of parts is the number of chosen parts times the number of different tooling configurations. All of the tooling changes can greatly increase the amount of time required to make the requisite parts.
Therefore, there is a need to provide an automatic bar feeder for feeding bar stock to a machining center and for supporting the bar stock during machining activity so that a user only has to set up the system and the feeder will continue to process a plurality of bars until the bar of raw material has been exhausted. Optimally, the system can also be set to process the bars as a group, performing each step on all of the bars present prior to changing the tooling, thereby significantly decreasing the machining time necessary. When the machines are CNC machines, set for milling operations, it is desirable that the bar stock be supported in vertically oriented fashion and movable by the computer controlled bed or work support table of the machine. It is also desirable that a milling head having multiple tools thereon be indexed to machining position for machining of parts from the bar stock. Unfortunately, to the detriment of CNC milling operations, the presence of a work supporting and positioning table beneath the machine support and positioning turret required the bar stock to be relatively short as compared to bar stock utilized in horizontal lathe type machines. This requirement typically causes a machine operator to make frequent bar stock changes, thus causing the productivity of the machine to accommodate the operator time that results from these frequent bar stock changes. Thus, it is desirable to minimize the operator time that is normally involved to install new bar stock at the end of a part machining cycle and thus enhance the productivity of the machine.
SUMMARY OF THE INVENTION
In keeping with the foregoing discussion, the objective of the present invention is to provide a bar feeder system having multiple work positioning stations for automatically feeding bars to a machining center. The bar feeder system of the present invention provides a plurality of mechanized chuck mechanisms for simultaneously holding a plurality of bars, four bars in the example shown, of raw material. Though the bar feeder system is designed for and discussed herein as having four work feeding and supporting chuck devices, such is not intended to be considered limiting of the spirit and scope of the present invention. The bar feeder system may more than four or less than four work supporting chuck mechanisms if desired. For positioning of the bar stock for machining, a spring loaded lifter mechanism is mounted to the machine turret and, when positioned above and in registry with the bar stock, is operated along the Z axis to grasp the upper end of a selected bar and to raise it as the bar is released by its chuck, after which the bar is again gripped by the chuck mechanism for that particular bar. As the positioned bars are machined, the mill completes each step of the machining process serially on each chuck supported bar prior to switching tooling to perform the next part machining step, thereby minimizing the time for the tool positioning sequences of the tool support and positioning turret of the machine and significantly decreasing the time necessary to complete a plurality of parts.
In keeping with the above discussion, the present invention takes the form of a machining center controlled bar feeding and holding mechanism having a base plate, which is mounted to the machine table. Attached to the base plate is a pedestal having a bar feeder top plate attached thereto. A plurality of clamping units, each being in the form of a mechanized collet chuck such as a pneumatically actuated chuck, is mounted in each corner or at other selected locations on the top plate. Each clamping unit is configured to hold a bar of raw material during machining thereof and to release the bar stock to permit its movement to a selected position relative to its chuck or to permit its replacement by fresh bar stock. Other objects and advantages of the invention will no doubt occur to those skilled in the art upon reading and understanding the following detailed description along with the accompanying drawings.
The bar feeder of the present invention is designed to allow automatic bar feeding and machining in vertical machining centers (VMCs) and horizontal machining centers (HMCs). The bar feeder may be used with machining centers in which the table rotates or is translated along X and Y move axes to position the work for machining and where the milling head either moves or is indexed to position selected machining tools for machining of the bar. The system could even be designed to rotate on the table top. A quick connect or other style connection or umbilical cable is used to connect control cables between the control of the machining center to the bar feeder to thus permit control of the chuck mechanisms of the bar feeder by the programmable control of the machining center. As necessary or desirable, an electronically controlled sequencer unit having electrical controls and electrically controlled pneumatic valves is controlled by the machining center to provide for selective actuation of the bar stock clamping mechanisms The bar feeder has a pedestal mounted on a base plate that can be bolted to a machine's table. The pedestal has an upper pedestal plate, to which is attached a bar feeder top plate to the pedestal. The bar feeder top plate has clamping units at each of the four corners. Collets in each clamping unit allow bar stock to be loaded, four bars at a time, one bar in each corner. The air-operated collet closers are independently controlled by the machine's programmed M functions. Currently, electro-pneumatic
5
C collet closers are used, which are capable of receiving and supporting bar stock up to one inch in diameter, however, any other suitable collet or clamp may also be used for feeding and support of bar stock of lesser or greater dimension. The collets of the chuck mechanisms may be changed out as desired for adapting the clamping assemblies for differing sizes of bar stock.
On a typical vertical machining cent
Andrews & Kurth LLP
Jackson James L.
Tsai Henry W. H.
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