Cutting – Processes – With subsequent handling
Reexamination Certificate
2000-01-27
2001-10-02
Ashley, Boyer D. (Department: 3724)
Cutting
Processes
With subsequent handling
C083S054000, C083S076800, C083S080000, C083S111000, C083S182000, C083S277000, C083S364000, C083S365000, C083S367000, C083S370000, C083S409000, C083S412000, C083S437100, C083S452000
Reexamination Certificate
active
06295906
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the field of specification tube cutting machinery and methods used to produce tubes and tubular pieces from longer stock tubes and, more particularly, to an apparatus and method for advancing and cutting a long tube and ejecting the remaining scrap tube from the cutting machine after the last specified piece is cut, thereby increasing the efficiency of the cutting operation and eliminating a time consuming and dangerous work step from the tube cutting process. In particular, the invention provides a gripper for securely holding the tube during the cutting operation. The gripper is attached to a carriage which is horizontally translatable with respect to the cutting apparatus. Additionally, a pusher is provided for automatically ejecting the last piece of cut tubing from the machine. The pusher is mounted on the carriage and reciprocates forward once the last specified piece of tubing has been cut in order to eject the end piece of tubing from the cutting machine. Preferably the tube cutting machine described herein is used in combination with a shear cutting device, although other methods of cutting tubing are known and would be considered operable in the present invention.
Methods for cutting long tubular stock into pieces of specified length are known. For example, in U.S. Pat. No. 2,837,156 to Brehm a conventional machine for cutting continuously advancing tubing is disclosed. This method, known as the Brehm method, is an example of a cutting method that is useful with the invention disclosed herein. In brief, the Brehm method involves the use of two dies, an inner die for contacting the inner surface of the tubing to be cut and an outer die for contacting the outer surface of the tubing to be cut. In order to cut the tubing, one die (generally the outer die) is moved with respect to the other die thereby “shearing” the tubing. This method for cutting tubing is preferred over other prior art methods that involve “sawing” the tubing because very little of the tubing is destroyed. Furthermore, the use of the Brehm method creates tube ends that are generally smooth and burr free.
Over the years, there have been many attempts to improve on the Brehm method in order to improve the quality and efficiency of the cutting process. For example, U.S. Pat. No. 4,205,569 to Horn et al. discloses a tube cutting apparatus using the Brehm method wherein multiple tube segments may be cut in a single shearing operation. After the tubing is cut, the slices of cut tubing are advanced onto an ejector rod that is then retracted to allow the cut tubing to fall into a collection bin. Additionally, the Horn et al. patent discloses dies that define inclined planes in order to cut tubes on a bias.
Similarly, U.S. Pat. No. 5,406,870 to Suitts et al. also discloses an improvement to the basic Brehm method in which the loader and feeder mechanisms for the cutting machine are integrated into one piece of equipment. In particular, in the Suitts et al. patent, a method and apparatus for cutting tubing is disclosed using the shear cutting method wherein the tubing is fed automatically to the cutter and is gripped and advanced to the cutting station. The cut tube is advanced along an arbor and is dropped off into a bin at the end of the arbor. The cutting machine of the Suitts et al. patent is equipped with an infrared sensing system that works in conjunction with computer programming to discard the scrap materials separately from the specification milled tubing without the need for a mechanical stop finger to determine the tube cutoff length.
Thus, while several prior art methods exist for continuously loading and cutting tubing while discarding any scrap created thereby, these methods tend to be complex and expensive, requiring the use of infrared sensing equipment, etc. Additionally, they also require the use of an arbor that extends past the end of the die and various forms of expensive and elaborate equipment add ons.
Accordingly, there exists a need for a method and apparatus for cutting tubing and automatically ejecting any leftover scrap tubing after all of the usable tubing has been cut that is mechanically simple and relatively inexpensive to fabricate and operate and which does not require the use of overly expensive or elaborate equipment to implement.
SUMMARY OF THE INVENTION
The present invention is an improved method and apparatus for advancing and cutting tube blanks into desired lengths and ejecting the unusable piece of tubing remaining after all of the usable cuts have been made. The machine for cutting the tubes of the present invention is preferably a standard supported shear type cutting machine.
In a preferred embodiment, the present invention consists of a cutting machine, such as a supported shear type cutting machine, for cutting a tubular workpiece and a base upon which the cutting machine is mounted. A carriage is mounted either on the base, or in close proximity thereto, in a manner that allows the carriage independent movement with respect to the base. The carriage is operatively connected to a motor, preferably a stepper motor, so that the carriage may be automatically moved precise distances during the cutting process. The carriage is also equipped with a device, such as grippers, for securing and advancing the tubular workpiece with the carriage. A pusher, shaped to engage the end of the tubular workpiece, is mounted on the carriage for reciprocal movement with respect to the carriage. The pusher includes a sensor, such as a contact switch, positioned on a portion of the carriage so that the position of the pusher with respect to the carriage may be ascertained at at least one point along the reciprocation route of the pusher.
The tube advancer, cutter, ejector of the present invention is preferably operated by selecting a tubular workpiece to be cut and positioning the workpiece on a cradle in the base in alignment with the cutter. After the cutting machine is programmed to make cuts at the desired lengths, the machine is activated. The carriage then begins to travel forward, thereby contacting the pusher with the back end of the tubular workpiece. The contact of the pusher with the tubular workpiece causes relative rearward movement of the pusher with respect to the carriage while the carriage continues to move forward. During this time the grippers, in an open position, continue to move with the carriage in a position coaxial with the tubular workpiece. Then, after the grippers have traveled a predefined distance down the length of the workpiece whereby they can securely grip and advance the workpiece, a sensor is activated sending a signal to activate the grippers to grip the tube and stop the pusher from further relative rearward movement with respect to the carriage. This signal can be sent via an infrared sensor or the like, but preferably is activated by a contact on the back of the pusher.
The carriage continues forward, now with the workpiece secured thereto, a designated cutting length and stopped. This length can be controlled using a stepper motor, various sensors, or other methods known in the art. The cutting machine is activated to make the desired cut and the carriage is moved again the designated length and the desired cut is made. This process continues until all of the desired lengths of tube have been cut from the tubular workpiece. The controller for the carriage, having calculated the number of cuts that have been made, then deactivates the grippers, thereby releasing hold of the remaining scrap piece of the tubular workpiece. The opening of the grippers signals the pusher to stroke forward, thereby ejecting the remaining piece of the workpiece through the cutting machine. The carriage then cycles back to the rear end of the base and is reset to cut another workpiece.
Accordingly, it is an object of the present invention to provide a tube advancer, cutter, ejector for cutting tubes of desired lengths from tubular workpieces which is mechanically simple and relatively inexpensive to fabricate and ope
Ashley Boyer D.
Production Tube Cutting, Inc.
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