DK178219B1 - Rotary abrasive grinder moving in a reciprocating movement across the workpiece - Google Patents

Abstract

An abrading machine is disclosed for abrasion of substantially plane items by use of rotating abrading discs (5,5'), which are moved simultaneously forwards and backwards transverse to the item and which preferably has downward extending abrasive lamellae. <??>The machine also preferably comprises one, typically two, opposite rotating abrading cylinders (7,7') fitted with elongated abrasive elements radially mounted on the abrading cylinder and has abrasive lamellae extending outwards from the cylinder. <??>By moving the abrading discs in a reciprocatory movement (4) transverse to the direction of feed (A) of the items it is achieved that traces etc. from the different abrasive properties of the abrading discs are eliminated as well as all parts of milled out areas etc. are evenly abraded, particularly if the abrading device is designed for using abrading discs with abrasive means comprising abrasive lamellae made of abrasive cloth and which extend downwards from the face of the abrading disc. <IMAGE>

Description

Grinding machine with rotary grinding wheels that are moved in a forward and reverse direction

BACKGROUND MOVEMENT ACROSS THE SUBJECT

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a grinding machine for grinding substantially flat blanks using rotary grinding wheels which simultaneously reciprocate, i.e. are moved back and forth, across the workpiece, and which preferably have downwardly abrasive slats.

It is preferred that the machine further comprises one, typically two, opposite rotary grinding cylinders, which are provided with elongated grinding elements radially mounted on the grinding cylinder and whose grinding slats extend radially from the cylinder.

BACKGROUND OF THE INVENTION

For grinding workpieces with a flat surface, a grinding belt mounted on a belt grinder is often used. However, this grinding method is only suitable for grinding completely flat surfaces, as cuts in some form of surface profiling will be '' smoothed out '' and the recessed surface will not be sanded by the grinding belt. At the same time, the precision of the grinding is thereby also not satisfactory in relation to many grinding tasks. This means that this grinding method is unsuitable for many grinding tasks within e.g. the furniture industry where gentle but complete grinding is needed. Similarly, the ffa metal industry is known to have complete deburring and abrasive or polishing surface treatment of punched, milled and laser-cut blanks, as well as from the manufacture and finishing of so-called "solid surface" blanks.

Within furniture production There are many different grinding tasks depending on the size and shape of the workpiece. Over the past decades, there has been a significant automation of the production of wood products within, among other things. furniture industry, and this also places new demands on the grinding tools. From, among others, WO 01/76824 and US-A-6,267,660, a rotary grinding tool is known in the form of a roller with grinding elements, a so-called grinding cylinder, which is suitable for grinding profiled or flat parts. Here, the flat piece is passed through the grinding system on a conveyor belt, roller table or the like in a continuous movement. The roller is rotated about its longitudinal axis and the rotary grinding tool is brought into contact with the surface, whereby a gentle grinding can take place. This grinding method is gentle due to a low grinding pressure, but can be a slow grinding process compared to grinding tasks on a generally flat surface exhibiting profiling, e.g. a door. In this case, it is necessary to move the grinding tool in a complicated movement around the profiles to ensure a complete grinding thereof. In this connection, it is also crucial which direction of rotation the grinding tool has in relation to the profile curves. As a result, the execution of the grinding task becomes slow and can at the same time be difficult to fully automate, which also makes the tool ineffective from a consideration of production costs.

Therefore, in order to achieve an efficient workflow by grinding items with profiling or other cutting in a substantially planar surface, one may be relied upon to apply a strip grinding to the planar surfaces and a rotary grinding tool to the profile areas where the grinding tool is moved around along the profiles.

It is therefore an object of the present invention to provide a grinding device which accommodates the disadvantages of the prior art, as described above, by enabling an efficient, simultaneous and uniform grinding or machining of a workpiece surface.

EP 1 175 961 A2 discloses a grinding device for grinding substantially planar blanks which comprises a means for feeding the blanks in a feeding direction, suspending means for suspending a plurality of grinding wheels for grinding one side of the blanks, means for rotating the grinding wheels about axes substantially perpendicular to the side of the blanks, and means for driving the grinding blades in a reciprocating motion across the blades direction of movement. The grinding device may further comprise a grinding cylinder which extends across the feed direction of the workpieces, where a choice can be made between using the grinding cylinder and the plurality of grinding wheels to grind one side of the workpieces, depending on the type of the workpieces. Thus, the grinding device can be used for several different types of workpieces.

Brief Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding device for grinding substantially planar blanks, comprising a means for feeding the blanks in a feeding direction, suspending means for suspending a plurality of grinding wheels for grinding one side of the blanks, means for driving rotation of the grinding wheels about axes substantially perpendicular to the blanks and means for driving the grinding wheels in a reciprocating movement across the conveying directions of the blanks, the grinding device further comprising at least one grinding cylinder, preferably two counter-rotating grinding cylinders arranged for grinding one side of the workpiece after being abraded by the abrasive discs, and preferably comprising abrasives extending radially from an elongate core, which abrasive cylinders extend across the direction of rotation and are driven to rotate about. their longitudinal axes.

A rotating grinding wheel grinding will be relatively aggressive as some cross-grinding of the workpieces occurs, and the device is typically designed for a relatively high grinding pressure and low rotational speeds of the grinding wheel so as not to deform any. profiles in the workpiece. Therefore, some "wild" grinding scratches will occur due to the rotation, but they will be removed by the two or more grinding cylinders, which will typically be fitted with a coarser grain size than the grinding wheels.

By moving the grinding wheels in an oscillating or reciprocating motion across the feed direction of the workpieces, it is partly achieved that tracks etc. from the abrasive disc's different abrasive ability across the diameter of the disc is eliminated, and on the other hand, all parts of the cutters are further smoothly decided, especially if the grinding device is preferably adapted to use abrasive discs comprising abrasive blades of a grinding sheet such as grinding sheets , the front of which has abrasive properties and which extends beyond the surface of the grinding wheel. Such abrasive wheels are described, for example, in US-A-4,493,170, in DE-A-24 11 749 and in EP-A-0 922 535.

The suspending means for suspending the abrasive discs are preferably one structure, so that the reciprocating movement of all the abrasive discs can be driven by the same member (s). Typically, this or these means may be an electric or hydraulic motor driving a shaft with an eccentric connection to the suspension means, but may, for example, consist of a resilient suspension of the suspension means and an electromagnet that turns on and off at a given frequency. of a relay, thereby exerting regular alternating forces between the suspending means and a stationary part of the grinding device.

The reciprocating movement across the feed directions of the workpieces may be a purely transverse movement, but may also comprise, for example, a circular or elliptical movement of the grinding wheels, provided that the movement pattern contains said transverse reciprocating movement. The reciprocating motion of the abrasive discs preferably has a stroke length of 40-100%, preferably 60-85%, of the diameter of the discs to eliminate the tendency for groove formation. Stroke is the distance between the two outermost positions in the transverse direction of the center axis of a grinding wheel.

It is preferred that the suspending means are arranged for hanging abrasive discs with abrasives extending from the surface of the abrasive disc, such abrasive discs as are known, for example, from EiS-A-4,493,170, from DE-A-24 11 749 and from EP-A 0 922 535, are particularly well suited for grinding recesses in the surface, such as cut-outs or breakthroughs. However, abrasive disks with flat abrasives can also be used in the device according to the invention, such as a resilient disc mounted with a grinding ring or abrasive paper, which can be varied in hardness according to the task.

The grinding device may advantageously comprise a plurality of abrasive discs with lower-cut grooves for receiving and retaining profile moldings which form part of elongated abrasive elements comprising abrasives, which grooves preferably extend in a substantially radial direction on the surface of the abrasive disc. Thereby, the abrasive discs can accommodate elongated abrasive elements, which consist of abrasives in the form of abrasive slats, the front of which has abrasive properties and the back of which is supported by support elements which are elastic in the direction of movement of the belt, so that the front of the abrasive canvas is pressed into systems with a relatively high abrasive pressure. with the surface to be decided, and the grinding can thereby partly take place at low feed rates of the grinding element, ie. low rotational speed of the wafer so that no impact occurs during the transition between surfaces and profiles, and partly so that the front of the abrasive canvas is kept in constant contact with the surface of the workpiece to be sanded so that a smooth and complete grinding is achieved. The support elements are preferably carried out by brushes, for example, natural brushes extending from the belt at a distance shorter than the abrasives, so that the support elements do not normally come into contact with the workpiece. The abrasives and support members are secured in a profile rail having a cross-section corresponding to the cross-section of the grooves so that the abrasive elements can be easily slid into and retained by the grooves and can also be easily removed from them, thereby replacing worn abrasive elements or changing the device. for another type of machining with other abrasive elements can be easily done. A suitable type of abrasive elements is described, for example, in WO-A-01/76824.

Further, restraint elements may be arranged between the abrasive elements so as to limit the deflection of the abrasives. The abutment elements act in such a way that the abrasive means, at a certain deflection thereof, engage with the backrest restraint element, which gives an increased stiffness to the abrasives and thus requires greater force for further bending. The abutment elements preferably comprise an abutment brush which exhibits a shorter length than the abrasive elements and which is mounted in a profile strip which is accommodated in a correspondingly cut groove on the abrasive disk.

It is further advantageous that the means for driving the rotation of the abrasive disks are arranged so that adjacent abrasive disks are rotated in the opposite direction, which, in conjunction with the reciprocating movement of the abrasive disks, results in smoother abrasions of all parts of the workpiece surface than if they rotates the same way. However, the latter is also an option of the present invention.

Alternatively, the machine may be constructed with an additional corresponding module of a plurality of abrasive discs so that it is possible to omit the abrasive cylinders.

Brief description of the drawing

A preferred embodiment of an abrasive device according to the invention is described below with reference to the accompanying drawing, in which

FIG. 1 shows the abrasive device from above with the series of parts removed so that the abrasive parts are exposed,

FIG. 2 shows a part of the abrasive device seen from the feed end in a vertical section through the abrasive discs, where the abrasive discs, their sled and drives are illustrated,

FIG. 3 is a side elevational view of the grinding device, and

FIG. 4 shows a grinding wheel, the grinding wheel's sled as well as their suspension and drive seen from the side in a partial section.

Detailed description of a grinding device according to the invention In the following, as an example of the invention and to illustrate it, a preferred embodiment of a grinding device according to the invention is described. The example is not to be construed as limiting the invention, and from the description and claims of the person skilled in the art, a variety of alternative devices can be made, all of which will be within the scope of the invention.

The abrasive device 1 comprises a conveyor belt 2 driven continuously or stepwise by a motor 3 and used to pass substantially flat parts through the abrasive device 1 from a feed end 4 in a feed direction indicated by arrow A shown in FIG. 1. The top of the workpiece then encounters six grinding wheels 5 arranged on a row transverse to the direction of the workpiece, the grinding wheels 5 being rotated alternately clockwise and counterclockwise, so that two adjacent grinding wheels 5 rotate in their respective directions as indicated. of the arrows BG in FIG. 1. Alternatively, the drive of the grinding wheels 5 can also be arranged so that all the grinding wheels 5 rotate in the same way. The abrasive discs 5 are mounted on a carriage 10 which during operation is moved in a reciprocating motion as indicated by the arrow H in FIG. 1, wherein the movement has a stroke such that the outermost positions of each of the abrasive discs 5 center positions in the reciprocating motion with a mutual distance of 75% of the abrasive discs 5. Each abrasive disc 5 consists of a disc 6, which has a plurality of undersized, radially extending grooves (not shown) on the underside facing down the workpiece, in which abrasive elements (not shown) are included which comprise a profile list holding a series of abrasive lamellae which have abrasive properties on their front and the back of which is supported by a series of support brushes. The abrasive members extend downwardly from the disc toward the workpiece substantially perpendicular to the rotational plane of the disc. A suitable type of such abrasive elements consisting of profile moldings, abrasive blades and brushes is described, for example, in WO-A-01/76824. The abrasive elements are oriented such that the front of the abrasive blades with abrasive properties are in the front direction of rotation. The abrasive elements are retained on the disc by the interaction between the profile molding and the undercut grooves having a dovetail-shaped cross-section of the opening, as well as by a ring extending around the periphery of the disc and closing the open end of the grooves at the periphery of the disc. This ring can be removed, after which the abrasive elements can be pushed out of the grooves and new abrasive elements can be pushed in. After passing the grinding wheels 5, the blanks of the conveyor belt 2 are further passed under two opposing rotating grinding cylinders 7, 7 'which remove any scratches in the blanks surface and give the surface the final finish. The grinding cylinders 7, 7 'are driven by associated motors 8, 8'. Suitable abrasive cylinders are described, for example, in WO-A-01/76824. The conveyor belt 2 then carries the items out of the grinding device at its outlet end 9.

The grinding wheels 5 are, as shown in Figs. 2-4, mounted on a common carriage 10 movable in transverse direction relative to the feed direction of the workpiece, the carriage 10 comprising two rails 11 running in three sets of wheels 12 fixedly mounted on a transverse beam 13 which Each of the abrasive washers 5 is mounted on a vertical shaft 15 which is mounted in the carriage 10 with bearings 24 so that it can freely rotate its vertical axis with minimal friction. The shaft 15 extends through the carriage 10 and has at its upper end a pulley 16 for cooperating with a V-belt 17 to drive the rotation of the grinding wheels 5. All abrasive discs 5 are driven by a motor 18 mounted on the carriage 10 and which has mounted on its pull shaft 19 a pulley 20. In FIG. 3 and 4, the extent 21 of the abrasive blades is also indicated in the vertical direction

The carriage 10's reciprocating movement across the feed directions of the blanks is driven by a separate motor 22 via an eccentric mechanism 23.

Claims (11)

An abrasive grinding device for substantially flat blanks, comprising means for feeding the blanks in a feeding direction, suspending means for suspending a plurality of grinding wheels for grinding one side of the blanks, means for driving rotation of the grinding wheels about axes substantially perpendicular to the side of the blanks, and means for driving the grinding wheels in a reciprocating movement across the blades direction of movement, characterized in that the grinding device further comprises at least one grinding cylinder arranged to grind a grinding wheel. side of the workpiece subsequently being abraded by the abrasive discs, and preferably comprising abrasives extending radially from an elongate core, the abrasive cylinder extending transversely of the feed direction and driven to rotate about its longitudinal axis. A grinding device according to claim 1, wherein the suspending means are arranged for hanging abrasive discs with abrasives extending from the surface of the abrasive disc. An abrasive device according to claim 1 or 2, comprising a plurality of abrasive discs with lower sheath grooves for receiving and retaining profile moldings forming part of elongated abrasive elements comprising abrasives, which grooves preferably extend in a substantially radial direction on the surface of the abrasive disc. . A grinding device according to any one of claims 1-3, wherein the means for driving the rotation of the grinding wheels are arranged so that adjacent grinding wheels are rotated in the opposite direction. A grinding device according to any one of claims 1-4, wherein the reciprocating movement of the grinding wheels has a stroke length of 40-100%, preferably 60-85%, of the diameter of the discs. A grinding device according to any one of claims 1-5, comprising a plurality of abrasive discs with abrasives comprising abrasive lamellae of an abrasive sheet, such as abrasive cloth, the front of the abrasive having abrasive properties and extending from the surface of the abrasive disk. An abrasive device according to claim 6, wherein the abrasive means comprise an elastic support member, preferably support bristles, which support the back of the abrasive slats, which support member is substantially the same length as the slats. An abrasive device according to claim 6 or 7, wherein the abrasive means are arranged in elongated abrasive elements which extend in a substantially radial direction on the surfaces of the abrasive discs. An abrasive device according to claim 8, wherein the abrasive elements comprise profile strips in which the abrasive means are secured and which are accommodated in lower-slit grooves in the abrasive discs. A grinding device according to claim 8 or 9, wherein retaining elements are arranged between the grinding elements. An abrasive device according to claim 10, wherein each of the abutment elements comprises a abutment brush which exhibits a shorter length than the abrasive elements and which is mounted in a profile strip accommodated in a corresponding undercut groove.