The present invention relates to apparatus, including a cartridge adapted to be removably mounted to the apparatus, for severing a tubular workpiece.
Tube cutting apparatus employed to sever sections of a continuous length of tubing or similar elongated stock fed from a source thereof such as a mill is known. Tube cutting apparatus in which a cut-off die set, driven by a ram assembly and clamped to the continuous length of tubing prior to and during the severing operation is exemplified by U.S. Pat. 4,653,368 issuing Mar. 31, 1987 to Riera et al., the disclosure of which being incorporated by reference herein. Riera discloses a tube cut-off die set including mechanism for providing a horizontal notching cut in a tubing wall followed by a vertical severing cut as the tube is fed through the set. The tub cut-off die set includes a movable upper shoe, a stationary lower shoe, guide posts and associated bearings affixed to the shoes and a ram providing the relative reciprocation between shoes. A tube holding arrangement therein comprises two axially spaced pairs of complementary die jaws being mounted on the lower die show for releasably clamping the tube. Downward reciprocation of a cam driver extending from the upper die shoe engages a pair of cam rollers associated with the lower die shoe to drive the die jaws about the tube and the blades between the jaw members.
The die set is used to cut sections of tubing as the tube is continuously manufactured. While suitable for its intended operation, the above-referenced die set does not allow for rapid adjustment of the die jaws so as to change their grip about the tube, and does not permit rapid replacement of the die jaws to accommodate different tube sizes and shapes. Since each tube diameter and cross section requires different jaw members it would be desirable to have jaw members that can be replaced and preset at a location spaced from the die set so that there would be no downtime of the tube-cutting apparatus. Further, a more compact jaw mounting arrangement would be desirable to reduce the overall size of the die set.
It is an object of this invention to provide a tube cut-off machine that maximizes the ease with which die jaws are replaced, to accommodate different tube diameters, without stopping the machine operation, and provide the user with an adjustment arrangement whereby the clamping force by the die jaws on the tube can be easily adjusted. Advantageously the use of a self-contained cartridge that includes the jaw members, cam followers and adjustment arrangement would allow the user to keep the machine cutting one particular diameter size while other cartridges are retrofitted with the appropriate jaw members, thereby reducing downtime of expensive machinery when it is time to change the jaws.
Part of the setup time of jaw members associated with the Riera machine was removing the cam driver prior to removal of jaw holders and then remounting the jaw holders and cam driver. This arrangement has an element of machine downtime. It would be desirable to provide rapid connecting and disconnecting arrangement for the cam driver. Desirably, such an arrangement would associate the desired jaw member spacing with the cam driver.
A further object of this invention is to provide a replaceable kit for use in a tube cutting machine which is simple, has jaw holders and jaw members preset, and is insertable as a unit. Advantageously, because the costs associated with the downtime of a machine is high and the costs of a cam driver relatively small, teardown and setup costs can be more than justified by such a kit. In this regard the kit advantageously permits only minimal downtime between removing cartridges and associated jaw holders when different tube diameters are to be cut.
One problem sometimes experienced in connection with tube severing machine is that the severed tube end portion is locally deformed and has what are termed "dimples." Tubes that are so formed are waste and thus costly. While the Riera construction including a horizontal notching blade cantilevered at the end of a cross slide in connection with the vertical severing blade has worked well in most situations, tube dimpling with some cross sections and tube thicknesses results. A tube severing arrangement which does not produce deformed cross sections would be desirable.
Another object of this invention is provision of a tube severing arrangement that permits severing of thicker and larger diametered tubes without breaking the blades or increasing the size of the machine into which they are mounted. Further, configuring the notching blade so as to have an offset portion surprisingly allows such tube cross sections to be cut.
The foregoing objects and advantages are accomplished by a tube cut-off machine for severing elongated material moving continuously longitudinally of its length, comprising relatively reciprocable upper and lower die shoes, one shoe mounting a tube cut-off blade and a cam driver, and tube clamping means for releasably clamping the tube during the severing operation. The tube clamping means includes two laterally spaced jaw holders each carrying a jaw member and positioning the tube clamping surfaces of the jaw members in confronting relation and a cam follower operably connected to one jaw holder.
In accordance with this invention, the tube clamping mans is characterized by a compact, self-contained, cartridge that is removably mounted to the die set as a single by replaceable unit. The cartridge comprises a carriage adapted to be mounted on the mounting surface of the lower die shoe so as to be stationary relative thereto, a pair of laterally spaced cam followers each being mounted on a cam holder one and the other follower being a roller and a replaceable wear pad, the two jaw holders and cam follower holders, respectively, being laterally spaced and slidably disposed on the carriage in confronting relation, bias means for laterally biasing the jaw holders apart, and adjustment means including a frame having an adjustment screw and operably associated with the carriage for adjusting the relative lateral separation between the jaw members, the frame maintaining the holders in side-by-side relation and the screw adjusting wear in the wear pad.
Advantageously the holders are separately manufactured and thus the assembly is less expensive because the need for a "beefed up" carriage construction is minimized. Separate parts weigh less, thus reducing forces needed during clamping/unclamping of the tube to overcome friction and inertia. Advantageously, the wear plate absorbs shock loads which might otherwise shear the pivot pin supporting a cam roller for rotation, resulting in costly repair and machine downtime.
A kit adapted to be mounted on the die set comprises the cam driver being operably disposed within the cartridge between the cam followers and their spacing preadjusted so that the jaw members are at their desired separation for clamping about the tube. The kit is mounted separately to the machine and requires minimal assembly time.
In accordance with one mounting arrangement, the cartridge is slid beneath a pair of gibs to secure the cartridge to the lower shoe, a dowel pin in a driver holder is connected to the upper shoe, and a pair of driver clamping plates on the driver holder are tightened behind the cam driver.
The cam driver has compliant load bars adapted to engage both cam followers to reduce uneven loads placed on the cam followers.
Further in accordance with this invention, the die set includes four bushings with their vertical axes disposed in a rectangular array with first, second and third adjacent pairs being secured together, respectively, by a first tie bar, a second tie bar and rail mounting plate, and the horizontal notching blade is vertically adjustable relative to a holding bar adapted to move between vertical planes including the first and third pair of bushings. Advantageously, a stiffening arrangement including three guide bushings including the second tie bar and rail mounting plate, the bashing axes forming a right triangular array, can stiffen the die set to obviate wobble of the notching blade.