EP1656237B1 - Control of a grinding device with grinding rollers on winding shafts - Google Patents

Abstract

The invention describes a control unit for a sanding machine, which winds and unwinds the abradant paper over a contact device. This control unit continuously detects the position of one or more of these sanding machines, the abradant unwinding, the movement of the transport system and the position of the workpiece. These parameters are used to regulate the sanding machine(s) in such a way that the workpieces are fed through and the sanding operation executed without interruption.

Description

The invention describes the method for controlling a grinding device with rollers, which are unwound to obtain the results of grinding on winding shafts and an intermediate contact device. Such a device is out WO-A-02/02270 known. It shows how the feeding of workpieces can be carried out continuously and the grinding processes can be carried out in a continuous sequence. This both when the direction of rotation of the abrasive carrier is relevant as well as if this is irrelevant.

To illustrate this invention serves
1, with the elevational view of a form of conventional sanding with flexible abrasives, comprising an endless sanding belt (11), which via a contact device (12) along the workpiece transport (13) to a drive roller (14) and a guide roller ( 15) rotates
the drawing 2 with the outline illustration of the invention underlying type of grinding, comprising a roll of flexible abrasive (16) lying on a transversely to the workpiece transport and in the feed direction r rotating unwinding shaft (17), a parallel to her rotating take-up shaft (18) and one between the two shafts, also transversely to the workpiece transport (13) extending contact device (12) with pre resp. downstream deflection rollers (19, 20), a feed system (21), and at the machine inlet with a by the control unit described in the invention (23) controlled barrier (22).

The conventional form of continuous surface grinding with flexible abrasives makes use of the endless belts, usually in an arrangement as shown in drawing 1. The disadvantages of endless belts are their relative cumbersome and costly packaging, its bulky shape during transport and storage, its limited service life due to its limited dimensions and its qualitative imperfections, due to the joint and the rapid repetition of any grain defects on the workpiece. The fact that their use could still not be dispensed with on the one hand was due to the requirement of relatively high grinding speeds for the most common materials and thus the need for correspondingly fast, continuous provision of grains for the grinding process, and secondly to the impossibility of conventional materials in the event of changes in grinding direction to achieve qualitatively identical results (in wood, for example, due to its fibrous structure). Only the continuous development of the sanding belt also allowed an equally continuous workpiece loading.

The invention is based on a Abwickelwelle (17) on which a roll (16) of abrasive on carrier material, usually an abrasive paper is applied, a contact device (12) and a take-up shaft (18) which receives the unwound abrasive again , The contact device is usually a contact roller or a continuous or composed of individual segments beam, ie a so-called sanding pad. Until the complete use of the abrasive, the sandpaper is wound back and forth again and again, after each pass, the take-up shaft respectively to the unwinding shaft and the unwinding shaft again to the take-up shaft. The principle of such grinding devices is described by Paul Ernst (Patent GB 1484851, 08.09.77 ) and Hans Rudolf Kündig ( WO 02/02270 A, 10.01.02 ). So far, however, the process for the continuous feeding of these devices and thus the grinding in constant succession was not solved.

The subject of the present invention is the combination of the grinding device described above with a controller (23), which solves the problem of discontinuities in feeding and the grinding process. The grinding device in the form known by the Paul Ernst patent In practice, it can only be used for grinding small batches or individual pieces. After reaching the end of the abrasive roll, this device is temporarily not available for feeding with workpieces until the direction of rotation is reversed. For materials that always have to be ground to feed in the same direction due to their structure (eg wood, as a rule, in the opposite direction), the rewinding process of the entire abrasive roll must first be awaited for such materials. At the usual cutting speeds for conventional materials (eg wood about 20 m / sec.) And the common abrasive roller lengths (around 50-200 meters), such a device experiences an interruption in the charge approximately every 2 to 8 seconds. This restriction is likely to be the reason that devices of this type have so far found no distribution.

The present invention now takes into account, on the one hand, the changing requirements of novel materials, surfaces and grinding processes. These (for example, the sanding of painted surfaces) often refer to homogeneous surfaces on which consistent sanding results even with opposite sanding directions. On the other hand, significantly lower removal rates are required, which are expediently achieved with lower grinding speeds (eg 5 m / sec.) And thus longer unwinding times. Furthermore, and above all, however, the control of the machine feed in function of the provision of abrasives by means of electronic controls is detachable, ie the bridging of discontinuities in the grinding operation has become manageable.

The controller (23) forming an integral part of the invention can manage various parameters, namely (the following list is not exhaustive):

I. the direction of rotation of the winding shafts

If it is not important for the grinding result, whether transverse or longitudinal or whether it is ground in co-rotation or counter-rotation to the direction of passage, it is sufficient to arrange the winding shafts as shown in drawing 2 and to redirect only the direction of rotation when reaching the sandpaper roll end. This procedure is sufficient for many homogeneous, d. H. non-fibrous materials.

II. The location of the grinding device itself

Is the grinding direction of concern, resp. if this must be maintained for all workpieces in a series, then the entire grinding device is turned after reaching the end of the sanding paper roll, in order to then take their course in the same direction again. In the arrangement shown in drawing 2, the rotation for this purpose is done by 180 degrees about the axis a of the grinding device. In principle, however, the grinding device, whether transversely or obliquely or longitudinally arranged, can also be rotated at any other angle.

III. the use of individual modules

If, in turn, the grinding direction is of concern, then several grinding devices - referred to below as assemblies - can also be used. Alternating are the one assembly in the grinding process, the other (after reaching the roll end) in the rapid return of the abrasive or the turning of the assembly. The controller assumes the appropriate allocation of the module functions to the grinding insert resp. the return or the turning.

IV: the position of the workpiece

Mechanically, visually or otherwise, the position of the workpiece is determined and its feed is controlled into the device itself or under the contact device (12). This, for example, by a correspondingly controlled barrier (22) at the inlet (in function of the winding progress) and / or by acting on the conveyor device itself.

V. the passage speed of the workpiece

Depending on the position of the workpiece to the winding device of the abrasive, the feed rate of the feed system (21) must be controlled accordingly, d. H. increased / reduced / stopped / started.

VI. the winding of the abrasive

The control system determines the remaining amount and time of abrasive material until it is reversed and initiates the optimal deceleration time of the winding and correspondingly the use of the individual assemblies (see III.). The controller can use the winding speed to optimize the usable time for the grinding process.

Only the combination of a grinding device on the principle of the winding shafts with a control described here brings a striking, practice-relevant improvement in the economics of the grinding process.

Claims (1)

1. Process to control a sanding machine, which winds and unwinds the abradant roll over a contact device (12), whereby the continuous monitoring, control and optimisation of the position of one or more of these sanding machines, the abradant winding, the feed movement and the position of the worked piece (13), enables the continuous feed of the device and non-stop sanding, thereby characterised in that the control system (23) makes a distinction between the following cases:

   a) if the sanding result is not affected by the direction of sanding with respect to the feed direction (longitudinal or lateral), or whether the sanding occurs in or against the direction of feed, the direction of rotation is reversed when the abradant roll reaches the end;

   b) if the sanding direction is of significance to the result, then either the entire sanding machine is turned at the end of the abradant roll, or a device with the required correct sanding orientation is chosen from a number of such devices.

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