DE3428039A1 - Pressure beam for long-belt sanding machine - Google Patents

Abstract

The invention relates to a pressure beam for a long-belt sanding machine which is subdivided into or plurality of pressure-beam members controllable independently of one another and is therefore suitable for so-called "free loading" and in which a flexible and elastic pressure mat presses the sanding belt against the workpiece surface by means of pressure cylinders. In order to reduce the sliding friction between pressure mat and sanding belt, distributor tubes with nozzle screws are fastened to a steel band of the pressure mat. A gaseous lubricant is directed through the distributor tubes via smoothing chambers in the lower bearing surface of the pressure mat between the latter and the sanding belt to form a load-bearing cushion. In addition, in order to ensure that the transition of the pressure mat between lowered and raised pressure-beam members rises gradually, the pressure mat according to the invention is held up against the adjusting elements of the compressed-air cylinders by tie rods and springs. In the process, however, while overcoming the spring preloading, it becomes detached at some of those pressure-beam members which are located in direct proximity to the lowered presure-beam members. The pressure beam can be used in machines for sanding the surface of plate-shaped workpieces which have relatively large deviations from an even surface, preferably in the woodworking industry. <IMAGE>

Description

description

a) Title of the invention pressure beam for long belt grinding machine b) Field of application of the invention The invention relates to the pressure beam of a Long belt sander that uses a variety of compressed air tools along the length a pressure beam carrier and the compressed air cylinder for delivery of a flexible and elastic pressure mat against the inside of a circumferential sanding belt or an additional support band, e.g. a lamella pressure band, is provided are and the sanding belt so against the surface of a on a transport device advanced workpiece is pressed and the control of the compressed air cylinder Above each of the compressed air cylinders assigned scanning elements actuated by the workpiece in connection with a corresponding delay circuit depending on the requirements of the Width or shape and position takes place on the transport of the workpieces to be processed and between the lower boundary surface of the pressure mat and the inside of the circumferential grinding or. Support band a standing under atmospheric pressure gaseous lubricant is supplied.

c) Characteristics of the known technical solutions The feed a pressurized gaseous Lubricant between the inside of a sanding belt and a pressure device is from DE-AS 1120925, DE-AS 2023540 and CH-PS 477263 are known.

In CH-PS 477263 a pressure device is described which the grinding attack on the workpiece edges along the transport direction by adjustable Regulated end pieces. Furthermore, this pressure device is in sections in chambers divided, the support air pressure of which is based on the specific requirements can be adjusted.

With the proposed device, however, can only work pieces of approximately the same width, which corresponds approximately to the length of the pressure device, to edit.

The pressure device also forms independently of its elastic Suspension overall a more or less rigid body, which allows for greater deviations the evenness of the workpiece surface despite the individually adjustable support air unable to adapt.

In DE-AS 2023540 a method and a device is described after which the adjustment of the pressure device during surface grinding by adjustment a higher support air pressure can be achieved compared to grinding to thickness target. This is also due to the more or less rigid pressure device determine that the regulation of the support pressure is not sufficient to achieve a complete Achieve adaptation to the workpiece surface if these deviations are greater of flatness. Although this device allows the processing of different Allows component widths, it can be noted that the workpieces are always on a fixed ruler must be passed under the pressure device and the processing of irregularly shaped workpieces, such as round table tops, not possible.

For machining workpieces with a greater deviation from have the evenness, pressure devices that deal with With the help of a flexible and elastic pressure mat, the Adjust the workpiece surface that deviates from the evenness.

Such devices are e.g. by DE-AS 1502449 DE-AS 2222616, DE-AS 2634829, DE-AS 26354739, DE-OS 284536 or CH-PS 483296 known.

These devices have flexible elastic pressure pads at their lower boundary surface, which is in contact with the rotating sanding belt stands up, so-called sliding linings to reduce friction. However, this means that the be knew disadvantages of sliding friction, such as increased heating and increased energy consumption and constant wear and tear of the leveling surfaces.

Pressure devices of the last-mentioned inventions are guaranteed but due to their subdivision into individually controllable pressure beam members in connection with appropriate scanning controls, the processing of irregularly shaped Workpieces, such as round table tops or the like.

as well as the machining of workpieces at any point within the working width or several workpieces next to each other through the grinding machine can be transported, which is known as so-called "Preie charging".

In the case of pressure beams with flexible, elastic pressure mats, please refer to DE-AS 2222616, DE-AS 2634329 and DE-OS 2635473 these pressure mats on the delivery devices, e.g.

Relieve compressed air zy that the pressure mat on the workpiece or put away, rigidly attached. If there is a workpiece under the pressure beam, the relevant infeed devices are lowered and those outside the longitudinal edges of the workpiece located raised. This can lead to the pressure mat in the transition area an impermissibly strong kink, which after a hurry has an impact on the grinding result can affect the longitudinal edge area.

In DE-AS 1777412 are by the arrangement of drag strips the scanning switches in connection with a corresponding pneumatic control the pressure bar members on both sides outside the longitudinal edges of the workpiece, at least approximately raised continuously to the starting position. This execution requires but not a small additional expense for the towing device and the pneumatic control.

d) Aim of the invention The aim of the invention is to remedy the disadvantages mentioned to eliminate.

e) Statement of the essence of the invention The object of the invention is to create a pressure beam, at the lower boundary surface of which a gaseous one Lubricant is supplied, which is subject to greater deviations from the evenness of the Adjusts workpiece surface, which is suitable for machining irregular workpiece shapes and automatically adapts to any position of the workpieces on the transport and the at the point between lowered and raised pressure beam members a continuous Guaranteed transition and this is realized with relatively little effort.

According to the invention the object is achieved in that above one low elongation band, which is preferably a steel band, with underneath thereon, e.g. by gluing attached elastic support, transversely to its lengthwise expansion and flattened manifolds circuitry associated with each pressure beam member with from below through the low-stretch band and one above on this, e.g. through Glued sealing plate, nozzle screws passing through holes are attached.

Each nozzle screw has a nozzle hole that is connected to the Interior of the manifold and a calming chamber in the elastic pad is in connection, the supply of the gaseous lubricant then taking place, when the associated pressure beam member is lowered.

Further embodiments according to the invention emerge from the characterizing Features in items 1 and 2 of the invention claims.

The invention enables the supply of a gaseous lubricant between the lower boundary surface of a larger deviations from the The elastic pressure mat and the inside of the workpiece adapt to the evenness of the workpiece surface a circumferential sanding or support belt for pressure beams, which is suitable for the so-called. 11Free loading "suitable, enabled.

Regardless of whether a gaseous lubricant is between the lower Boundary surface of the pressure mat and the inside of a circumferential sanding or support band is supplied or not, the object is still thereby according to the invention solved that the pressure mat with the help of each pressure beam member positionally assigned Tie rods and springs are held up against the actuating elements of the compressed air cylinder is detached from the adjusting elements while overcoming the bias of the springs can be. The preload can be adjusted using self-locking nuts so that that this is greater than the force of gravity resulting from the weight of the pressure mat and is about 1.2 to 2 times that.

Further advantageous refinements of the invention emerge from the characteristic features in points 4 and 5.

of the creation claims.

The invention provides a continuous transition of the pressure mat on the pressure beam for low-cost loading between lowered and raised pressure beam sections guaranteed, i.e. the pressure mat rises outside the actual grinding area gradually and continuously, and this can be done with relatively little effort.

f) Exemplary Embodiment The invention will be based on an exemplary embodiment are explained in more detail.

The accompanying drawings show: FIG. 1 a view of the pressure bar a long belt sander viewed in the workpiece throughput direction; Fig. 2 a Section of the pressure bar in the course A - A according to FIG. 1 with the associated workpiece scanning element and schematic control; Fig. 3 shows a partial section of the pressure beam in the course B - B according to FIG. 2; FIG. 4 shows a cut-open detail in the course C - C according to FIG Fig. 3; 5 shows a cut-open detail in the course D - D moderately Fig. 3; w Fig. 6 shows a section on the end side of the pressure bar, where the sanding belt enters in the course E - E according to FIG. 1; 7 shows a partial section analogous to FIG. 6, but on the end side of the pressure beam, where the sanding belt runs out in the course F - F according to FIG. 1; FIG. 8 shows a cut-open detail along the course G - G according to FIG Fig. 6.

In the case of a machine for grinding plate-shaped workpieces 1 regular or irregular shape with corresponding transport 2, such as powered Belts or rolls, and arranged transversely to the feed direction above the same Abrasive belt 3 guided over rollers and additional support belt 4, such as lamellar pressure belt or even without this, there is a pressure bar 5 for pressing the rotating sanding belt 3 provided against the workpiece surface.

On the suspension bolt 6, the pressure beam 5 is not shown in detail Machine body attached (Fig. 1).

The pressure beam 5 consists of a pressure beam carrier 7, in which a Large number of evenly spaced air cylinders 8 are attached with the piston rod 9 pointing downwards. Through this arrangement the pressure beam 5 is functionally divided into individual pressure beam members. On the piston rods 9 is via various intermediate elements 33, 34 the flexible and elastic pressure mat lo attached (Fig. 1 and 2).

In cooperation with each pressure beam member in terms of position and circuitry associated scanning elements 11 and corresponding delay circuit 12 exists the possibility of the pressure mat OK and thus the sanding belt 3 in sections lower at those points and raise again after the grinding process where this required depending on the width or shape and the position of the workpieces 1 on the transport 2 is. For this purpose, according to Fig. 2 in the feed direction in front of the pressure beam 5 is a Follower roller 13 is present, which is raised by the incoming workpiece 1, and thereby the actuation of the proximity sensor 14 by the switching flag 15 triggers. With the actuation a switching signal given which for Activation of the circuit 12, which can e.g. be an electronic pulse counter, leads. After a certain delay time of the delay circuit 12 has elapsed is an output signal for the switching of valves 16,17, which the relevant Bring pressure beam section into working position, used.

At the end of the workpiece, the given switching signal is used to reset the pressure beam members. The delay time for lowering and raising the pressure beam links can be adjusted independently of each other.

The pressure mat lo is according to FIGS. 2 and 3 for the supply a gaseous lubricant set up on its lower boundary surface 13. For this purpose, the low-stretch band 19, which is preferably a steel band is, with underneath it, e.g. by gluing attached elastic pad 20 and on top of it, also e.g. by gluing attached elastic sealing plate 20, flattened distribution pipes 22 transversely to the longitudinal extension of the pressure mat lo attached, each manifold 22 in the relevant pressure beam member positional and is assigned in terms of circuitry. The manifold 22 is from below with the help tightened by nozzle screws 23 to the sealing plate 21 and the low-stretch band 19. As a result, the pressure mat remains flexible in the longitudinal direction, while the distribution pipes 22 have a stiffening effect across it, which is advantageous. The nozzle screws 23 have a nozzle bore 24, which on the one hand into the interior of the distributor pipe 22 and on the other hand in the calming chamber 25 of in the support 20 circular cross-section opens.

Via the supply line 26, an under controllable atmospheric Pressurized gaseous8 lubricant, preferably air, into the manifold 22 and from there passed through the nozzle bore 24 into the calming chamber 25. here the gaseous lubricant can be evenly distributed and then passes over the Annular gap of the calming chamber 25 on the lower boundary surface 18 of the pressure mat 1o with the formation of a stable cushion 27 on the inside of the circumferential belts 3, 4 off. Thanks to the # cushioning 27 of the gaseous lubricant the heating and the energy requirement during grinding are reduced and so is wear switched off by so-called sliding coatings.

The gaseous lubricant is only assigned accordingly Valves 17 as a function of the scanning signals of the scanning elements 11 and associated Delay circuit 12 is supplied when the associated air cylinder the Pressure mat 1o against the sanding belt 3 and thus against the workpiece surface place. This leaves the consumption of the gaseous lubricant on those sections and limited moments where a workpiece 1 is ground.

The spaces between the manifolds 22 above the sealing plate 21 are filled in by strips 28, which are advantageously applied by gluing are. The upper edge of the strips 23 and the manifolds 22 forms because of them at the same height a flat support surface on which an elongated, flattened, the the actual grinding pressure generating hose 29 which can be filled with gas is applied.

The support 20 of the pressure mat lo consists of an elastic gas-impermeable Material, e.g. rubber or plastic and has a coating on its lower side 30 made of friction-reducing material, e.g. made of bonded flake graphite. she serves to ensure that appropriate emergency running properties are guaranteed if excessive local workpiece elevations press over the stable cushion 27 or if with too little overpressure of the gaseous lubricant is worked, or if it to disturbances in the supply of the same.

Wach Fig. 2, the pressure mat lo with the help of the tie rods 31 and the springs 32 to the adjusting screws 33, which are located in the on the piston rod 9 of the compressed air cylinder 8 attached crossbar 34 are held. Included is the bias of the springs 32 with the help of the nuts 35 adjusted so that they is greater than the force of gravity resulting from the weight of the pressure mat lo. It is about 1.2 to 2 times the same.

When lowering the air cylinder 8 according to the extent of Workpieces 1, the pressure mat lo with the lower half of it circumferential sanding belt 3 is fed to the workpiece surface. With the immediate adjacent raised compressed air cylinders 8 detaches the pressure mat lo from the system on the adjusting screws 33 with reinforcement of the preload of the springs 32 from and over as many pressure beam members as the internal stiffness which is still essentially flexible pressure mat 10 is required. The pressure mat 1o comes back to rest on the adjusting screws after a few pressure bar links 33 of the raised air cylinder 8. This is a continuous and gradual one Transition of the pressure mat lo from the lowered to the raised position on both sides guaranteed outside the longitudinal edges of the workpiece (Fig. 1).

The tie rods 31 have a nipple 36 at their lower end, which in Recesses 37 in the retaining strips 38 are non-rotatable but can be inclined by the small angle 39 intervenes. This eliminates jamming of the tie rod 31 in the transition area outside the longitudinal edges of the workpiece avoided (Fig. 1, 2, 3, 4).

The lower part of the pressure mat 1o is above the holding bar 38 Threaded bolts 40 which are inserted into the ends of the sealed manifolds 22 or other Retaining elements are screwed in, attached with the help of nuts 41, being below of the retaining strips 38 a tape 42 extending over the length of all retaining strips 38, the It is preferably a steel band that is enclosed loose but securely in place. Against this Belt 42 is supported by the elongated, flattened one, which can be filled with gas via the connecting piece 43 Hose 29 down towards the top. The gas pressure acting in the hose 29 acts downwards on top of the lower part of the pressure mat lo and is considered more effective Effective grinding pressure because the grinding or

Support band 3, 4 on the workpiece 1 touching the lower part of the pressure mat lo is raised slightly (Fig. 2).

The cross bar 34 has depressions 44 for at its outer ends the inclusion of the springs 32 and slots 45 for hanging the tie rods on (Fig. 2 and 5). As a result, the entire pressure mat lo can relatively quickly from the pressure beam 5 can be detached.

So that the cross bar 34 does not pivot about the piston rod axis can, there are two pins 46 fm on the side of it Pressure beam support 7 attached. The mobility of the cross bar 34 in the direction of the piston rod movement remains fully intact.

The adjusting screws 33 can be used to adjust the pressure mat io can be adjusted accordingly in their vertical position.

There is a holder on each of the left and right outer pressure mat ends 47 with the aid of a clamping plate 48 and clamping screws 49, not shown in detail attached to the low-stretch band 19. The holder 47 has pins on both sides So on, which are arranged at the level of the low-stretch band 19 (Fig. 6 and 7).

On the side where the grinding or support belt 3, 4 runs in, are Rollers 51 are rotatably mounted on the pin So. They attack with enough play into vertical guides 52 of retaining tabs 53 (FIG. 8). This will put the on the pressure mat intercepted longitudinal forces. The point of application of force is at the same time in the neutral zone of the low-stretch band 19, so that vertical force components, which can influence the grinding result, do not arise.

In addition, the end of the pressure mat is at the same height as the adjacent pressure beam members. The elongated pin 50 also protrudes with a correspondingly large play in vertical grooves 54 of the retaining tabs 53. As a result, the vertical movement of the pressure mat end corresponds to the lowered one or limited raised position of the pressure beam members.

The retaining tabs 53 are on the bracket 55, which is on the pressure beam support 7 is attached, mounted adjustable in the direction of the pressure beam longitudinal alignment. The adjustment takes place with the help of the screws 56. This allows the pressure mat Adjust lo so that the manifolds 22 are exactly below the associated compressed air cylinder 8 come to rest. At the same time, the pressure mat can lo exactly in the direction Align the longitudinal pressure beam.

The pressure mat is terminated with the help of tie rods -31 and springs 32 held on AbatEtsplatten 57 in the upper vertical end position by the The preload of the springs 32 is somewhat greater than that caused by the ~ weight of the pressure mat end up conditional gravity, the attachment of the tie rods 31 or springs 32 to the bracket 47 or support plate 57 is carried out in the same way as for the retaining strips 38 or crossbars 34 in the middle part of the pressure mat io.

On the side where the grinding or support belt 3, 4 runs out, is the end of the pressure mat hung in the same way, only with the difference that on the Pin 50 disks 58 are attached, which are attached to lateral guide surfaces 59 of The retaining tabs 60 rest with little play (FIG. 7). This is the side Guide of the pressure mat end secured.

Claims (5)

Invention # sans # ru'che 1. Pressure beam for a long belt sander, of a multitude of compressed air cylinders over the length of a pressure beam carrier and the pressure cylinder for delivery of a flexible and elastic Pressure mat against the inside of a circumferential sanding belt or an additional one Support belt, e.g. a lamellar pressure belt, are provided and the sanding belt thus against the surface of a workpiece advanced on a transport is pressed and the control of the compressed air cylinder over each of the compressed air cylinder assigned by the workpiece actuated scanning elements in connection with a corresponding delay circuit depending on the width or shape and position takes place on the transport of the workpieces to be processed and between the lower Boundary surface of the pressure mat and the inner surface of the circumferential sanding respectively. Support band is a gaseous under atmospheric pressure Lubricant can be supplied, characterized in that above a low-stretch Belt (19), which is preferably a steel belt, with underneath it, e.g. through Gluing attached elastic support (20) transversely to its lengthwise expansion and flattened manifolds circuitry associated with each pressure beam member (22) with from below through the low-stretch band and one above on this, e.g. Sealing plate (21) applied by gluing, passing through bores Nozzle screws (23) are attached and each nozzle tube (23) has a nozzle hole (24) shows which with the interior of the distributor pipe (22) and a calming chamber (25) of circular cross-section in the elastic support (20) in connection stands and each manifold (22) is connected to a supply line (26) and each Supply line (26) has a valve (17) and the valve (17) is then open, when the associated pressure deflection member is lowered and the pressure in the supply line can be regulated and that the spaces between the individual distributor pipes (22) filled above the sealing plate (21) by strips (28) made of elastic material are and the strips (28) on the sealing plate (21), z0B. by gluing and the thickness of the strips (28) corresponds to the height of the distribution pipes (22). 2. Pressure bar according to item 1, characterized in that the elastic Support (20) consists of gas-impermeable material and on its inside the circumferential belts (3, 4) facing side a coating (30) made of friction-reducing Material, e.g. bound flake graphite 3. Pressure beam for long belt sander according to the generic term according to point 1 but regardless of whether a gaseous Lubricant between the lower boundary surface of the pressure mat and the inside the rotating grinding or. Support band is fed or not, characterized in that that the pressure mat (io) is positionally assigned with the help of each pressure beam member Tie rods (31) and springs (32) upwards to the adjusting elements of the compressed air cylinder (8) can be counter-held and overcoming the bias of the springs (32) of the Control elements can be detached and the bias of the springs (32) by self-locking Nut (35) is adjustable so that this is greater than that from the weight of the Pressure mat (lo) resulting gravity and the preload is about 1.2- to 2 times the same. 4. Pressure bar according to item 3, characterized in that the tie rods (31) a nipple (36) is attached below and the nipple (36) in recesses (3) of retaining strips, (38) engages in a rotationally secure manner but tiltable at a small angle (39) and the retaining strips (38) the upper limit of a threaded bolt (40) and nuts (41) which can be clamped between two straps (19, 42) and possibly further elements (21, 22, 28), elongated, flattened and gas-fillable hose (29) forms and the retaining bar (38) on the adjusting screws (33) of a cross bar (34) which is attached to the piston rod (9) of the compressed air cylinder (3) is attached, and the crossbar (34) has indentations (44) in which the springs (32) rest and slots (45) are present, through which the tie rods (31) with the springs (32) can be suspended and the crossbar (34) by pins (46) in the pressure beam carrier (7) against pivoting about the piston rod axis is secured. 5. Pressure bar according to items 3 and 4, characterized in that on left and right outer pressure mat end each have a holder (47) on the low-stretch Band (19) is attached and on the bracket (47) at the level of the low-stretch band (19) protrude laterally pins (50), which on one side, where the grinding or support belt (3, 4) runs in, take up rollers (51) in a rotatable manner and the rollers (51) engage in vertical guides (52) of retaining tabs (53) and those on the other On the side where the grinding or support belt (3, 4) runs out, disks (58) are attached and the disks (58) on lateral guide surfaces (59) of retaining tabs (60) with little play and the retaining tabs (53, 60) on the pressure beam support (7) are attached and in the direction of the pressure beam longitudinal alignment with the help of screws (56) are displaceable and the retaining tabs (53, 60) have grooves (54) into which the extended tenons (So) protrude with a correspondingly large amount of play and the vertical one Movement of the pressure mat ends can be limited and the pressure mat ends with the help of tie rods (31) and adjustable springs (32) on support plates (57) in the upper vertical position can be maintained and the preload of the springs (32) is slightly greater than the force of gravity caused by the dead weight of the pressure plate ends.