BELT GRINDER FOR SHARPENING PIPES

The subject of the invention is a belt grinder for sharpening pipes in accordance with generic term of the patent claim 1.

Sharpening of pipes, in particular pipes from stainless steel with a disc grinder or with a belt grinder also straight running Trumen is possible. The work leads to an unsatisfactory result. With these machines no circle-arc-shaped erosion and from it a surface, whose Schleifbild is irregular, result. Besides it is not possible, with an abrasive, which is induced in one level to produce a clean cross section on a tubular body because always only an essentially linienförmiger contact exists.

It is also already a Rohrschleifer well-known, which works with a sanding belt, which rotates roles arranged of this, which roles sit relatively to each other at the ends of two around the axis of rotation of the drift role tiltable thigh from a drift role at the driving motor propelled around two beabstandet. To working on a pipe the latter against the Trum of the sanding belt between the two relatively to each other mobile roles led and thus partly umschlungen. Looping is the larger, the smaller the spreading angle of the two thighs is. The sanding belt keeps the two thighs spreading feather/spring strained at each time.

At this device the spring action increasing with increasing Umschlingungswinkel of the sanding belt by the pipe which can be worked on, which can be overcome again only by an appropriate increase of the contact pressure of the volume to the pipe which can be worked on, is unfavorable. This has the consequence that the pipe is on one side subjected with higher contact pressure to the sanding belt and thus an again uneven Schleifbild causes. In the further the forces, which are necessary, are to be received in order a sufficient looping of the pipe which can be worked on, more highly than for the treatment necessary tracking force of the sanding belt. They lead to the fast fatigue of the operator. The high contact pressures, which are necessary for large looping, cause on the other hand an accordingly large resistance at the sanding belt, and as consequence a increased engine performance becomes necessary for the drive, which leads to an increase of the total weight of the grinding machine.

Task of the available invention is the creation of a belt grinder, with which with small energy expenditure a looping of approximately 180 degrees of angle of a pipe is possible, without thereby a substantially increased drive power is necessary.

This task is solved by a belt grinder in accordance with the characteristics of the patent claim 1.

Succeeds by the arrangement of the rocker at a being certain lever to make the sanding belt length available without substantial increase of the tape tension, necessary in the case of the rear-end collision into the workpiece for looping. Additionally this approximately linear tape tension is supported by the use of an elbow lever, by which Kraft of the feather/spring receives an essentially linear process. The distance between the role can be adapted by the adjustableness of the length of the first being certain arm at the end of the tiltable lever arm and the role on the first ascertainable lever to the diameter of the workpiece which can be worked on. The arrangement of the handle at the mobile poor in the end of a lever makes it possible to the operator to swivel the mobile arm actively without increasing the tracking force of the sanding belt to the workpiece substantially.

On the basis an illustrated remark example the invention is more near described. Show

Figure 1

a schematic representation of the well-known belt grinder with two V-shaped arranged relatively to each other tiltable swivel arms,

Figure 2

a side view of the grinding machine according to invention except interference with the workpiece and

Figure 3

a side view of the grinding machine according to invention in interference with the workpiece.

In figure 1 the represented from the state of the art belt grinder 1 is on the right side the power supply unit 3, e.g. an electric motor or a pneumatic motor admitted as rectangle represented. By the inlet 5 the appropriate energy (electricity or air) is supplied. With a switch 7 the power supply unit 3 can be switched on and off. At the front side end of the power supply unit 3 a drift role 9. sits in the further is fastened to the power supply unit of 3 two swivel arms 11 and 13, of which at least one is tiltable stored around the axis of rotation A in the proximity of the drift role of 9. At the 3 arm 11 connected with the power supply unit a far handle 15 is firmly fastened, to which the operator holds the machine 1 with the second hand. The swivel arm 13 is forced away by spreading a working feather/spring 17 by the being certain arm 11 (arrow P). At the ends of the two arms 11.13 detour wheels 19.21 are put on, which carry an endless sanding belt 23 rotating around these two detour wheels 19.21 and the drift role of 9.

In the figure 1 the well-known grinding machine is represented during the sharpening procedure, i.e. between the two detour wheels 19.21 the sanding belt 23 loops a tubular workpiece 25 in an angle beta of less than 180°. In relaxed condition the Trum 26 of the sanding belt 23 tangential from the detour wheel 19 to the detour wheel 21 runs. By the Umschlingungswinkel beta are against each other-led the two detour wheels 19.21 against Kraft of the feather/spring 17. The Umschlingungswinkel at the workpiece 25 is determined by Kraft F, with which the operator presses the belt grinder 1 against the workpiece 25.

In the arrangement according to invention of the belt grinder 1 in accordance with the figures 2 and 3, in which for same parts the same designations and reference symbols are used as in figure 1, again the drift role of 9 sits at the end of the power supply unit 3, and being certain first, that is fastened detour wheel 19 basic arm 11 to it. The tiltable arm 13, which carries the detour wheel 21, is not linked and around the axis of rotation of the Umlenkrades 21 tiltable, contrary to the state of the art, close at the power supply unit 3, but at the end one with this likewise firmly connected second arm 27. At the end of this second arm an additional detour wheel 29 is fastened. The handle 15 is taken up in the execution according to invention at the tiltable arm 13. This handle 15 sits at the end one winkelig at the swivel arm 13 of fastened arm 31. In the further an elbow lever arm 33 is fastened or trained to the swivel arm 13, at whose end the feather/spring 17 attacks. The second end of the feather/spring 17 is fastened to the second being certain arm 27. In a preferential arrangement of the invention the elbow lever arm 33 essentially right-angled to the axle F of the feather/spring 17 extends. The first being certain, the detour wheel 19 basic arm 11 can exhibit a firm length or, as represented in the example in accordance with the figures 2 and 3, when telescope arm implemented its, so that its length L, i.e. the distance of the axis of rotation of the role are changeable 19 to the axis of rotation A of the drift role of 9 and concomitantly the distance to the guide roller 21 for adjustment to the diameter D of the workpiece 25.

In the following the function mode of the belt grinder according to invention 1 is more near described. In the no-load operation position in accordance with figure 2 the Trum 26 tangential from the detour wheel 21 to the detour wheel 19 extends. The sanding belt 23 is kept strained in this position by the feather/spring 17 between the four detour wheels 9.19.21.29. Lowers now if the operator, who holds the grinding machine 1 with a hand to the power supply unit 3 and with the other one to the hand grip the 15, the sanding belt 23 from above on the tubular workpiece 25, then the initially straight-lined running Trum 26 around the workpiece 25 is led around (Umschlingungswinkel beta). By the arc-shaped process of the sanding belt 23 the distance between the two detour wheels 19 and 21 is shortened. The shortening takes place via active swivelling of the swivel arm 13 with a hand the operator the counterclockwise around the axis of rotation of the Umlenkrads 29. The detour wheel 21 approaches therefore the detour wheel 19 on an circle-arc-shaped course, which deviates only insignificantly from a straight line. With increasing angle of traverse of the swivel arm 13 the angle between the axle of the feather/spring 17 and the elbow lever arm 33 becomes larger. This leads 17 on the swivel arm 13 to a continuous decrease Kraft of the feather/spring. Despite the detour of the sanding belt of 23 over approximately 180 degrees of angle, the traction power on the sanding belt 23 remains essentially unchanged and thus the contact pressure in the entire looping range beta approximately same, independently of whether the diameter is D of the workpiece large or small. This independence is made possible by the fact that the detour wheel is 19 at the first being certain arm 11 relative the detour wheel 21 adjustable. During processing a larger diameter D is the distance between the detour wheels 19.21 in the no-load operation more largely, accordingly is already the basic distance for the treatment of a smaller pipe (see figure 3) already smaller before beginning of the work. The attitude of the distance takes place before the beginning of the treatment.

The arrangement of the handle 15 at the tiltable arm 13 and besides at the end of the arm for 31 possible makes it to release the lagging of the arm 13 not only by the relative motion of workpiece 25 to the machine 1 to support but actively by swivelling the arm 13 with the arm 31.