Material or article handling – Horizontally swinging load support – Swinging about pivot
Reexamination Certificate
1997-04-21
2001-02-06
Underwood, Donald W. (Department: 2652)
Material or article handling
Horizontally swinging load support
Swinging about pivot
C029S03300H, C198S346100, C269S020000, C269S014000
Reexamination Certificate
active
06183188
ABSTRACT:
BACKGROUND
1. Field of the Invention
The invention relates to a work pallet changer, and in particular to a manually operated work pallet changer system.
2. Background of the Invention
In machine shops using large, expensive automatic machine tools, such as the Vertical Machining Center, the Horizontal Machine Center, and Drilling and Tapping machines, it is desirable to keep the machine tool busy in order to make it an effective and efficient investment. Many machine shops have adopted the use of work pallet changers also known as pallet indexers. The use of a pallet indexer permits a machine tool operator to assemble the work on portable pallets and to efficiently move the work to and from a machine tool work table by transferring assembled work pallets. This procedure avoids unnecessary downtime otherwise required to setup and teardown the work directly on the work table.
Using such an indexer, a new work pallet is setup off line while the machining proceeds on a previously assembled work pallet. The indexer is then used to quickly remove a pallet and its completed work from the machine tool and to replace it with the newly setup work pallet. The machine tool is inoperative only during the short time required to exchange the work pallets. In this way the machine tool is kept busy, and the owner's investment is maximized.
A variety of devices and methods have been proposed for this purpose. Among these devices are a class of pallet indexers which operate on a shuttle or side-by-side principle, as for example the pallet changer illustrated in U.S. Pat. No. 5,156,254. Another popular class of pallet indexers uses a rotary or carousel principle, as illustrated for example in U.S. Pat. No. 5,018,617.
Some indexers are manually operated, while many others are semi-automatic or even fully automatic in operation. Though these pallet indexers achieve the goal of keeping the machine tool busy, they tend to suffer from two major problems which undermine the goal of maximizing the owner's investment.
The first problem relates to the manner in which the side-to-side indexers interfere with a machine tool operator's ability to physically monitor the work in progress. These shuttle-type indexers often include a portion connecting two side units. That portion extends outwardly from the machine tool near a position at which the machine tool operator must stand in order to effectively observe and monitor the machining operation. In such cases, the machine tool operator must lean across this connecting portion in order to observe and listen to the work as it proceeds. Though it is possible for the machinist to work in this manner, the leaning-across increases fatigue and interferes with both his efficiency and his ability to use skills effectively to insure the machining is properly carried out. This shortcoming tends to be present in both the manually operated and the automatic indexers of the side-to-side configuration.
The second common problem relates to the complexity of the automatic and the semi-automatic indexers, and even many of the manually operated devices. These indexers are expensive to purchase and are often costly to maintain. What is gained in efficient machine shop operation, is lost in an increased, and often hidden cost for indexer maintenance and repair. As a result, the apparent savings are somewhat illusory, particularly in the smaller and mid-sized machine shop.
It would be desirable to provide a work pallet changer that is relatively inexpensive to purchase, that provides an increase in productivity by being easy to operate, that is configured to permit the machine tool operator to monitor the work without undue fatigue, and which presents the shop owner with few hidden costs related to upkeep.
SUMMARY OF THE INVENTION
The present invention meets these requirements by providing a manually operated work pallet changer providing simple handling for a pair of work pallets. The pallet changer is inexpensive, is easy to install and to adjust, is easily maintained, and rotates out of the machinist's way once a work pallet exchange is completed.
In a specific embodiment of one aspect of the invention, a manually operated work pallet changer includes a heavy, floor supported base. A horizontal platform is pivotally attached to the base, and defines a primary vertical axis extending through the center of the base. The horizontal platform rotates, with respect to the base and the primary axis, between a work pallet-setup position and a work pallet-exchange position. The horizontal platform extends outwardly from the primary axis in cantilever fashion. The outwardly extending portion of the platform includes a bearing which defines a second vertical axis parallel to the primary axis. A generally rectangular pallet guide platform is rotatably attached at the bearing, above and parallel to the horizontal platform, and is thus able to rotate around the secondary axis. A pair of work pallet guides are aligned in opposite directions on top of the pallet guide platform.
Rotation of the pallet guide platform about the secondary axis by 180° brings first one and then the other work pallet guide into the work pallet-exchange position. Pivoting the horizontal platform around the primary axis shifts the pallet guide platform between the work pallet-exchange position and the work pallet-setup position, away from the machine tool.
In a specific embodiment of another aspect of the invention, an air-bearing work pallet receiver includes a planar top surface having a plurality of small openings connected through an automatic valve to a compressed gas. When the valve is opened, the gas is ejected through the small openings, forming an air-bearing surface which floats the heavy work pallets and facilitates their movement and careful alignment on the machine tool. The receiver also includes a deployable clamping plate which mates with a congruent opening formed on the underside of the work pallet. Once the deployed clamping plate has engaged the opening, the work pallet is retained against the lift of the air-bearing and is coarsely aligned atop the work pallet receiver. Finally, the receiver includes a pair of retractable locating pins which are withdrawn below the air-bearing surface while a work pallet is being moved and adjusted, and which are then extended into corresponding openings on the underside of the work pallet providing a precise and repeatable alignment during the machining operations. The clamping plate is then moved from a deployed receiving position to a work pallet clamping position.
In another embodiment of the invention, a manually operated work pallet changer system includes a pallet changer and an air-bearing work pallet receiver, as described above.
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Midaco's “Side by Side” Pallet System, sales brochure and specifciation, Midaco Corp., 2000 East Toughy Ave., Elk Grove Village, Illinois 60007.
The Siegel Rotary Pallet System, sales brochure, Siegel Systems Div., Macro Tool & Machine Co., Inc., 361 Route 55, LaGrangeville, NY 12540.
The Siegel Shuttle Pallet System, sales brochure, Siegel Systems Div., Macro Tool & Machine Co., Inc., 361 Route 55, LaGrangeville, NY 12540.
Randazzo Steven J.
Solorio Mario F.
Wu Hao
Buckley Robert
Underwood Donald W.
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