Paring device

Details Paring device Paring device

2001-06-05

2003-04-01

Watts, Douglas D. (Department: 3724)

Cutlery

Means for cutting elongate, strand-encircling sheath

Longitudinally

C030S090100

Reexamination Certificate

active

06539634

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
Applicants claims priority under 35 U.S.C. §119 of German Application Nos. 100 27 315.7, 100 27 316.5 and 200 09 868.3, all filed Jun. 5, 2000.
1. Field of the Invention
The invention relates to a paring device for cylindrical objects, in particular for plastic tubes, comprising a plurality of rollers assembled to form a running trough; at least one paring knife; and at least one paring head having a guide roll; as well as a spindle drive connecting the running trough and the paring head. The spindle drive includes a spindle guide provided with a slot-shaped opening and a spindle rotating in the opening and having an actuation handle, whereby the paring head and the running trough, between which the cylindrical object can be fixed, can be driven against each other.
2. The Prior Art
The surfaces of tubes, cables or cylindrical rods frequently have to be worked before they are processed further. For example, it is necessary to remove an insulation layer from cables. Also, before welding plastic tubes, the surface of the tubes have to be pared. This process removes dirt accumulated from the manufacturing process, as well as material changes caused by aging, which may appear on the surface, for example due to damage caused by UV-radiation or weathering. Otherwise inadequate welding would result.
To remove a surface layer that is as thin as possible from the object to be worked in an exact manner, the cutting depth of the knife has to be exactly adjusted. This adjustment of the knife, which is required when the cutting depth is changed or when the knife is exchanged, requires skill and much experience on part of the machine operator. If the knife is aligned incorrectly, only inadequate quality of the treatment is frequently achieved. Either too much material is removed from the objects to be worked, which for tubes may reduce the remaining cross section to an inadmissible extent, or surface layers damaged by age or inclusions of dirt are not removed completely. If the knife is aligned in an inclined manner, it is possible that undesirable scores or grooves remain on the object to be pared, which may impair the welding process.
Products with rolled shoulders exhibit a certain ovality conditioned by the manufacturing process, which appears even in tubes with a large diameter due to longer storage periods. Such ovality of tubes is deemed undesirable during paring because with a fixed spacing between the running rollers and the knife on the paring head, such ovality causes the machining process to become irregular and unclean, so that it is not possible to obtain satisfactory treatment results. In extreme cases, areas of the tube may remain unworked, whereas other areas of the tube are pared to an impermissible depth.
For removing a surface layer from tubes or similar objects, a paring device of the type specified above is known, for example from DE 93 05 220 U, in which the paring knife is connected with the paring head in a fixed manner. In this paring device, the cutting depth of the paring knife has to be exactly adjusted in order to exactly pare from the object to be treated a surface layer that is as thin as possible. This exact adjustment is required whenever the cutting depth is changed, as well as with each exchange of the knife in order to avoid obtaining a treatment that is poor in quality due to incorrect alignment of the paring knife.
Furthermore, it is known in connection with paring knives to align the guide roll with a slanted setting in relation to the direction in which the running rollers of the running trough are running, in order to drive the paring device in the axial direction of the object to be pared, such as a tube or the like. The paring device can be guided in this way around the object with a helical movement, whereby the pitch associated with the slanted position of the guide roll has to be adapted to the diameter of the object, as well as to the width of the paring knife.
For special applications such as, for example for attaching tube clamps for drilling, or tube junctions to plastic tubes, it is necessary to pare only half of the circumference of the tube. However, with the conventional paring device described above, it is possible only to continuously pare the entire circumference of the object to be treated without discontinuing the treatment, and to axially displace the paring device on the object to be pared. Paring only half of the circumference of the tube, thus a saddle zone on the tube, is difficult to achieve with the known paring device. Furthermore, space is limited on construction sites, particularly in construction pits when drilling clamps have to be mounted or tube branches attached at a later time, to the extent that a conventional tube scraper cannot be employed in most cases.
Therefore, the problem of the invention is to provide a paring device that, in addition to treating the entire circumference of the object to be pared, is suited for treating saddle zones on a cylindrical object as well, without deteriorating in this way the handiness or the quality of the treatment process.
SUMMARY OF THE INVENTION
This problem is solved according to the invention in that at least one guide roller rotates freely about its own axis in a bearing block mounted on the paring head. The bearing block is freely pivoted about an eccentric axis perpendicular to the guide roller axis. As the paring device moves around the cylindrical object to be pared, the axis of the guide roller swivels to an angle relative to the axis of the object, so that the paring device moves helically around the cylindrical object. When the direction of movement of the paring device is reversed, the bearing block pivots as well, so that with an alternating movement of the paring device around half of the circumference of the cylindrical object, the paring device is always advanced in the same axial direction. It is thus possible with the paring device as defined by the invention to pare also the area of a cylindrical object required for drilling clamps or tube branches without having to work the complete circumference of the object. It is therefore possible to distinctly reduce the time required for working a cylindrical object without any change in the quality of the treatment when only the required surface areas are scraped off. Because the center of rotation of the bearing block is located outside of its center, the entire bearing block, as the paring device is moving, will automatically swivel into a position that effects an axial advance of the paring device on the object to be pared.
Two coaxial guide rollers are preferably supported in the bearing block. Guiding the paring device on the cylindrical object to be pared is enhanced in this way. Inaccuracies caused in the course of the treatment such as paring the same spot a number of times, or the formation of grooves are also avoided.
Furthermore, the bearing block may be elastically secured on the paring head. It is possible in that way for the guide rollers to apply contact pressure on the object to be pared.
As an alternative to the above, it is possible to support the guide rollers themselves in the bearing block in an elastic manner. A constant contact pressure of the guide rollers against the object to be pared can be achieved in this way as well, so that a high treatment quality is achieved through high guiding accuracy.
According to a preferred embodiment of the invention, the axes of the guide rollers can be aligned and fixed in at least one angular position in relation to the axis of the object to be pared. The pitch of the helical movement at which the paring device is driven around the object can thus be adjusted in a fixed manner. The operator is able in this way to assure that the cutting width of the paring knife is not exceeded by the pitch, so that a high treatment quality can be achieved. For differently sized diameters of the objects to be pared, the pitch can be adjusted via the inclined position of the axes of the guide rollers in such a way that optimal cutting

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