Metal working – Plural diverse manufacturing apparatus including means for... – Separate tool stations for selective or successive operation...
Reexamination Certificate
1999-07-02
2001-07-10
Briggs, William (Department: 3722)
Metal working
Plural diverse manufacturing apparatus including means for...
Separate tool stations for selective or successive operation...
C029S03300H, C029S795000, C226S076000
Reexamination Certificate
active
06256862
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to apparatus for forming wooden frames and the like, and more particularly, to providing discrete connector plates from a coil of connector plate stock.
Connector plates having integrally formed nail-like teeth depending from a surface are used to fabricate various wooden frames, crates, trusses, and the like. Connector plates are used because of the ease and speed of fabrication which translates to lower costs. Typically, wooden members are placed on a jig table, and positioned in the form of the desired frame. Then, connector plates are positioned on opposite sides of the frame joints. The teeth of the connector plates are then embedded into the wooden members, usually, with a press.
To improve efficiency, at least some known presses include feed systems that index a desired length of connector plate coil stock into the press machine. The machine cuts a connector plate from the coil, positions the plate over the frame joint, and then presses the connector plate to embed the teeth of the connector plate into the wooden members. An example of such a press is described in U.S. Pat. No. 3,913,816.
The press described in Pat. No. 3,913,816 includes a coil feed assembly that advances two coils into the press. The coils are typically fabricated from an elongate strip of sheet metal connector plate coil stock having a plurality of spaced open slots formed by pre-punched, integrally formed elongate nail-like teeth extending from one surface of the connector plate stock. The first coil supplies connector plates for the top side of the frame joint and the second coil supplies connector plates for the bottom side of the frame joint. The connector plate coil stock is advanced into the press by a slide block coupled to an air cylinder. Additional air cylinders move clamps into engagement with the coils of connector plate coil stock to hold the coil stock to the slide block as the slide block advances the coil stock into the press. The clamps are released by retracting the air cylinders and then the slide block is moved back to its original position by retracting the air cylinder. The process is then repeated for the next pair of connector plates. This press relies on the action of air cylinders to move the coil stock into the press. As air cylinders wear they become less reliable and sometimes stick in one position. A buildup of dirt on the cylinder rod may prevent the rod from moving smoothly through the cylinder seals and may cause the cylinder rod to stick or move slowly. The 3,913,816 press includes air cylinders for advancing the first coil, and air cylinders for advancing the second coil. If any one cylinder moves slower than the others or sticks, the press could malfunction and jam.
It would be desirable to provide a connector plate coil advance drive that is reliable to smoothly advance connector plate coil stock into a press without the use of hydraulic or air cylinders.
SUMMARY OF THE INVENTION
These and other objects may be attained by a coil advance drive apparatus for connector plate coils. The coil advance drive apparatus includes a frame, a motor coupled to the frame, at least one elongate coil support member coupled to the frame, and at least one drive wheel operatively coupled to the motor. Each drive wheel is configured to engage the connector plate coil stock.
Particularly, the coil support member includes a plurality of grooves extending longitudinally in one surface of the support member. The grooves are configured to receive the pre-punched teeth extending from the connector plate coil stock. The drive wheel includes a plurality of teeth extending from a circumferential surface of the drive wheel. The teeth are configured to engage the open slots in the connector plate coil stock so as to move the coil stock along the support member as the drive wheel rotates. An elongate coil guide cover is coupled to the surface of each coil support member above the grooves. The coil guide cover is configured to at least partially cover the surface of the coil support member to form a channel. The channel is configured to permit the connector plate stock to move along the surface of the support member with the teeth located in the grooves and the coil stock prevented from bending up off the coil support by the coil support cover.
The apparatus also includes at least one coil mounting arm coupled to the frame of the apparatus. Each coil mounting arm includes an elongate portion mounted at one end to the frame and includes a coil mounting hub located at the other end of the elongate portion. The coil mounting hub is configured to rotatably mount a coil of connector plate stock.
A magnetic proximity switch is operatively coupled to at least one drive wheel to count the revolutions of the drive wheel. This information permits indexing and cutting the proper length of connector plate stock from the coil to form the desired length connector plate.
In operation, the coil advance drive apparatus is typically attached to a shear for cutting the connector plates to length or a combination shear/press that cuts the connector plate from the coil stock and presses the connector plate into wooden members of a frame to join the members together in one operation. A coil of connector plate stock is mounted on a coil mounting arm of the drive apparatus. Specifically, the coil is mounted on the coil mounting hub of the mounting arm. The coil stock is them fed into the drive apparatus so that the coil stock slides through the coil support member with the nail-like teeth of the coil stock located in the grooves of the support member. The drive wheel engages the coil stock with the teeth extending from the drive wheel engaging the open slots of the coil stock. As the drive wheel rotates, the coil stock is advanced by the action of the rotating teeth engaging the coil stock in the slots of the coil stock. The coil stock is advanced through the channel formed by the support member and the coil support cover.
The proximity switch counts the revolutions of the drive wheel so that the drive wheel can be stopped when the desired length of connector plate coil stock is advanced into the shear to be cut. After the shear has cut a connector plate from the coil, the drive motor can be re-energized to advance another length of connector plate coil stock into the shear for cutting.
The above described coil advance drive apparatus smoothly advances connector plate coil stock into a press The drive wheel that advances the coil stock through the apparatus is reliable and does not have the inherent problems of hydraulic or air cylinders, such as sticking in one position or slow movement of the cylinder rod due to dirt buildup.
REFERENCES:
patent: 3577851 (1971-05-01), Detheridge
patent: 3580018 (1971-05-01), Gott
patent: 3806014 (1974-04-01), Bulli
patent: 3895708 (1975-07-01), Jureit et al.
patent: 3910089 (1975-10-01), Meier
patent: 3913816 (1975-10-01), Jureit et al.
patent: 3970386 (1976-07-01), Wohlrab
patent: 4670976 (1987-06-01), Stridsberg et al.
patent: 4887452 (1989-12-01), Bakermans
patent: 5019209 (1991-05-01), Hiraide et al.
patent: 5725140 (1998-03-01), Weber et al.
patent: 2033789 (1981-10-01), None
Jin Kathy Liuhui
Olden Michael Marc
Briggs William
MiTek Holdings, Inc.
Senniger Powers Leavitt & Roedel
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