EP2476512B1 - Strip blow off device - Google Patents

Description

Technical area

The invention relates to a Bandabblasvorrichtung for a grinding belt in a processing machine, which is intended for the machining of workpieces, which are preferably made of wood, wood-like materials and / or metal.

State of the art

The operation of belt grinding machines produces dust when grinding workpieces. This dust contaminates the workpiece and also the abrasive belt. This dust interferes with the further processing of the workpiece and also affects the grinding performance of the grinding belt. To clean a workpiece was in the DE 42 328 30 C5 proposed to provide a blow-off and suction device which is suitable for removing a workpiece from the dust, and which comprises a plurality of outlet openings on a plurality of blowing devices, which are distributed over the working width of the grinding machine. These blowing devices are individually controllable, so that each for a blowing device or a group of blowing devices, a control valve and a sensor is provided which detects the contour of the workpiece to be machined and provides information to a control unit, according to the contour of the individual blowing devices or a Group of adjacent blowing devices drives.

While such a device is capable of reducing the amount of air required, it does not achieve an improved cleaning effect over a perpetual blow-off device.

To get better results when cleaning the sanding belt, use the EP 0724933 A1 a nozzle assembly which reaches the entire abrasive belt gapless and over the entire width by a movement of the nozzle assembly. Also in the CH 405975 A For this reason, a nozzle arrangement oscillates back and forth across the width of the grinding belt. However, such a movement of the nozzle assembly requires a more complex construction. In addition, the way that the nozzle assembly is moved in these embodiments is also very large, so that a high frequency, with which the movement is usually performed, lead to a very high mechanical wear and the components must be replaced more often.

Presentation of the invention

The present invention is based on the problem that the cleaning effect of some of the conventional blow-off devices are indeed sufficient for the cleaning of a workpiece, since there are usually smooth surfaces, but provide only insufficient performance for the cleaning of an abrasive belt. Although other conventional blow-off devices can adequately clean an abrasive belt, these devices have very high mechanical wear due to the high operating frequency.

It is therefore an object of the present invention to provide a tape blowing apparatus which is less worn than the conventional apparatus but at the same time capable of sufficiently cleaning an abrasive aggregate.

This object is solved by the features of claim 1. Further features embodying the invention are contained in the subclaims.

A belt blowing device according to the invention for cleaning a grinding unit with a revolving grinding belt for grinding a workpiece comprises a nozzle arrangement with a plurality of nozzles for blowing air, which are arranged in the direction across the grinding unit and directed to this, wherein the nozzle arrangement at least one interface and conduit means directing air from the interface to the nozzles, and wherein the interface directs the air into the conduit means, control means for controlling the blowing out of air through the nozzle assembly, the nozzle assembly having a plurality of multi-nozzle nozzle rows , Wherein at least two of the rows of nozzles are arranged offset to one another and the control device is arranged so that the individual rows of nozzles can each be operated independently of each other. The arrangement of several rows of nozzles, which are operated independently, the cleaning effect is increased by the motion simulation of the Bandabblasvorrichtung, so that can also be used for a sanding belt. At the same time, wear of the device is reduced by the fact that there is no strong movement.

The individual rows of nozzles are preferably operated sequentially one after the other. As a result, the cleaning result of the abrasive belt is further improved.

Further, the nozzle assembly is preferably made in a continuous casting of aluminum or plastic, so that the lines and interfaces more preferably all can be configured integrally with the nozzles. Further preferred is the nozzle arrangement, preferably the Entire Bandabblasvorrichtung, movably arranged. This movement again preferably takes place in a plane parallel to the running direction of the grinding belt, more preferably in a direction parallel or perpendicular to the running direction. The movement is preferably carried out at a frequency of 0.1 Hz to 1.5 Hz, but preferably at 0.5 Hz. This further increases the cleaning effect, in particular together with a sequential control of the nozzle rows.

In this case, the nozzles of the individual rows of nozzles are each offset so that the staggered nozzle rows are substantially on a straight line connecting. That is, the offset distance of each row of nozzles to the next row of nozzles is always constant, preferably about 30 mm. Again, an improved cleaning effect is achieved by the arrangement of the obliquely offset rows of nozzles.

The nozzles of one or more nozzle rows are preferably inclined obliquely to the grinding belt, in particular to the side.

A grinding unit or the belt blow-off device is preferably used in a processing machine, which also has a conveyor for workpieces.

Brief description of the figures

• FIG. 1 shows a schematic structure of a processing machine having a tape blowing apparatus according to the present invention and a grinding unit;
• FIG. 2 shows a nozzle assembly as aluminum extruded profile according to the present invention;
• FIG. 3 shows a first possible control of the nozzle rows, in one embodiment with three groups of nozzle rows.
• FIG. 4 shows a second possible control of the nozzle rows, in one embodiment with three groups of nozzle rows
• FIG. 5 shows a nozzle assembly in an enlarged view with three rows of nozzles;
• FIG. 6 shows a nozzle assembly in an enlarged view with four rows of nozzles in which the nozzles are inclined to each other.

Description of the preferred embodiment

In FIG. 1 is a processing machine to see a conveyor 5 with a conveyor belt 6, on which a workpiece 4 is located, a rotating grinding unit 2 with and a Bandabblasvorrichtung 1 has. The workpiece 4 is transported by conveyor 5 on the conveyor belt 6 to the grinding unit 2 and processed there by this grinding belt 3. The revolving grinding unit 2 in the present embodiment is a grinding belt 3, since this is a commonly used grinding unit 2. Other moving grinding units are included in the invention. The grinding dust produced during grinding then settles both on the workpiece 4 and on the grinding belt 3. Although the following description describes embodiments of a belt blowing device, this belt blowing device is in principle suitable for being used also for the cleaning of workpieces. In such a case, the design of the Bandabblasvorrichtung relative to the grinding unit, the funded workpiece to bezieher.

The tape blowing apparatus 1 has a nozzle assembly 8 and a control device (not shown).

In FIG. 2 a Bandabblasvorrichtung 1 can be seen, which includes three nozzle rows 10. A nozzle row 10 consists of a continuous casting profile with a plurality of individual nozzles. The term "nozzles" in the simplest form also includes mere holes or holes in the continuous casting profile through which the air is expelled. Preferably, however, the nozzles are additional elements designed specifically for directional ejection of the air. Such nozzles are exemplary in the FIGS. 5 and 6 to recognize. In the present embodiment, special nozzles are threaded into a continuous casting profile containing compressed air lines connecting the nozzles 12 together. The nozzles 12 are screwed into receptacles 9 provided for this purpose. However, the individual nozzles 12 need not be screwed into a continuous casting profile, they can also be connected with a simple plug connection, welded or be formed integrally with the continuous casting profile. The continuous cast profile itself is again preferably made of aluminum, a steel or a plastic.

The individual rows of nozzles 10 may each be designed as individual continuous casting profiles, or may be formed in one piece, so that two or more rows of nozzles are formed in a single continuous casting profile. The individual rows of nozzles 10 can preferably be stackable in a modular manner, so that further rows of nozzles 10 can be easily attached to the existing nozzle arrangement 8. A nozzle arrangement 8 comprises at least two rows of nozzles 10, but preferably three, four or even more, which are arranged one above the other, ie offset in the z-direction. More preferably, the rows of nozzles 10 are offset in the x-direction to each other by a distance v, the ideally 25th mm to 35 mm, more preferably 30 mm. The distance v is preferably constant, so that the individual nozzle rows 10 are offset from one another by the same distance and the corresponding nozzles 12 of the different groups G1 G2, G3 lie on a straight line. In this case, the nozzle arrangement 8 has one or more interfaces 11 via which compressed air is introduced from an external compressed air line or a compressed air suction device (not shown). The compressed air introduction is preferably determined by a solenoid valve unit which controls the air supply in the various compressed air lines by opening and closing the corresponding valves.

It should be noted that while compressed air is the preferred fluid for use with the present invention, it is contemplated that various fluids or gases best suited to the particular purpose and environment may be used. For use of the present tape blowing device in woodworking, humid air may also be used which, for example, may additionally have a humidity of from 20% to 80%, allowing the blown-off dust to bind in the moisture and therefore be easier to remove.

In principle, it is preferable to use continuous casting profiles in which the compressed air lines to the nozzles 12 are already integrated, but it is possible to implement the basic principle of the invention with simple pressure hoses, each leading to one or more nozzles 12 (eg Multi-ported hose to which the nozzles 12 are attached) or to supply each nozzle individually with compressed air through a hose.

The nozzle assembly 8 is arranged so that it is directed to the sanding belt 3, more specifically, that the nozzles 12 of the nozzle rows 10 are directed to the sanding belt 3, ie the ejected air can hit the sanding belt 3. Generally is in FIG. 5 An embodiment is shown in which the orientation of the nozzles 12 is formed perpendicular to the abrasive belt 3. However, an orientation is preferred in which the nozzles 12 are aligned obliquely to the grinding belt 3 (see FIG. 6 ). Slanting may theoretically mean in any direction, for example, in one direction in or against the direction of travel of the abrasive belt 3 during operation, which corresponds to alignment in a yz plane, but is preferably oriented in the xy plane, as in FIG FIG. 6 is shown.

The inclination of the nozzles 12 is preferably in a range of about 25 ° to 55 ° to the side, preferably 30 ° to 40 ° and more preferably about 35 ° to a straight orientation, as in FIG. 5 you can see. Of course, the nozzles 12 may be inclined in the same direction both in the x-direction and in the y-direction. Further, the inclination of the nozzles 12 is preferably made to be alternate, so that the individual nozzle groups G1, G2, G3 are inclined in opposite directions.

It is also possible to make the entire nozzle arrangement 8 movable or rotatable, so that an inclination can be provided which is opposite or in the running direction L, in FIG FIG. 1 indicated by an arrow, tilted. Such a tendency is as a dashed design in FIG. 1 shown. In general, however, an alignment parallel to the sanding belt 3 is preferred, in which the nozzle assembly 8 is arranged across the sanding belt 3 and, as mentioned above, perpendicular to the sanding belt.

The nozzle assembly 8 or the entire Bandabblasvorrichtung 1 is further preferably also mounted linearly movable. The movement is preferably in a plane E, which extends parallel to the grinding belt 3, in a preferred embodiment, the movement is transverse or parallel to Running direction L in the plane E. The movement takes place in a frequency of 0.1 Hz to 1.5 Hz, preferably at 0.5 Hz.

The movement is generated, for example, by an oscillating cylinder (not shown), which controls the nozzle arrangement or even only the nozzle rows (the
Continuous casting profile) can move and is stored even outside the arrangement, or outside the nozzle rows. Preferably, this oscillating cylinder has a coupling which is arranged between the cylinder and the respective moving element and can compensate for mechanical stresses.

The control of the individual nozzle rows 10 or the individual nozzles 12 is generally independent of each other. This means that, for example, a valve on the
Interface can be provided which can cut off the supply of compressed air into the pressure lines of the nozzle rows 10, so that the nozzles 12 of the corresponding row of nozzles 10 do not expel air. It is also conceivable that each individual nozzle is provided with a valve, but preferably the line of the entire row of nozzles 10 is provided with only one valve and so all the nozzles 12 of a row of nozzles 10 are controlled simultaneously. Another possibility is stop valves, which can be provided in the pressure lines, so that only a part of a row of nozzles 10 from a respective group can blow out air (eg only the left half or the left third). Alternatively, it can also be provided on both sides of the nozzle assembly 8, an interface for the supply of compressed air, so that both sides can be controlled and the left or right half each individually blow air. Of course, this approach is not on "halves." limited, but the stop valves, the nozzle rows each divide into thirds or quarters. In the extreme case, each nozzle can be controlled individually. A fairly simple realization of a stop valve could be single blind plugs inserted into a nozzle hole instead of a nozzle can be used and then block the compressed air line, so that the air flow is interrupted. Such blind plugs can be made, for example, of rubber and in a form which is adapted to the respective pressure line.

Since the nozzles could possibly be damaged by the sanding belt, for example if the sanding belt gets into contact with the nozzles during a change or a malfunction occurs, a web can be provided around the nozzles and / or between the nozzles or the nozzle rows Surface of the nozzle assembly on which the nozzles are arranged, lifts, so that the nozzles are protected. For example. could this web between the nozzle rows protrude vertically, so that an oblique orientation of the nozzle as in FIG. 6 can blow out the air without being obstructed by the bridge. The web is preferably slightly higher than the nozzles protrude.

The FIGS. 3 and 4 show preferred activations of the nozzle rows 10. The individual nozzle groups have a preset actuation time t1, t2, t3 within one cycle. One cycle describes the activation of the groups G1, G2, G3, which repeats itself again and again. The drive timing marks the beginning of the ejection of air from the nozzles of the corresponding group. The duration for which the respective group is activated, ie air inflates, can be adjusted. In the FIGS. 3 and 4 Examples of a nozzle arrangement are shown which shows three groups whose activation time, that is to say the time duration for which a group blows out air, is preferably distributed uniformly over one cycle. If several four or more rows of nozzles are present, they are also preferably driven uniformly over one cycle. Basically, one can say that in the preferred embodiment, one cycle with the drive time of the first driven group (here G1 begins, and ends with the switching off of the last controlled group (here G3).

By way of example, the control for the in FIG. 3 shown embodiment described with three rows of nozzles. The solenoid valve of group 1 is driven for a certain time, preferably one turn of the belt 3 (for example 1 sec at a belt revolution of 2 m / sec and a belt length of 2 m), and blown out air from group 1. Immediately after switching off group 1, group 2 is switched on for the same time. The same happens after switching off the group 2 with group 3. In the present embodiment, with three rows of nozzles 10 after switching off the group 3, so after a cycle, again group 1 is activated and the process repeated. With more groups or with fewer groups, the procedure is analogous, with the first group being switched on again when the last group is switched off. However, the method described above is merely preferred and various modifications are possible. For example, the subsequent group could not be activated directly after the preceding group was switched off, but simultaneously with the shutdown. Or the operation of the individual groups can also overlap. Also, the control can generally be done in any order. For 3 groups, this may only lead to a reversal of the control, but in four groups the order can also be G1-G3-G2-G4 or G1-G2-G4-G3. In addition, the activation of different groups can also take place simultaneously. For example, if there are six rows of nozzles 10, group 1 and group 4 would blow out simultaneously for the six groups, group 2 and group 5, and group 3 and group 6.

By the alternating control of the nozzles 12, an oscillation movement of the system can be simulated, so that kept the air consumption as low as possible, a homogeneous Cleaning the sanding belt 3 achieved while a fixed system can be used.

The length of the control can be adjusted via an operating terminal. To simplify this, a cycle whose duration can be set separately and preferably as a function of the grinding belt length and / or the grinding belt speed is assumed to be 100% or 1. Accordingly, in FIG. 3, the length of the nozzle operation of the individual groups G1, G2, G3 is set to 33.3% and 1/3, respectively. Thus group 2 switches on simultaneously with the disconnection of group 1. Preferably, an overlap of the control of the individual group can be set, so that, for example, group 1 is switched off only after half of the Zeitimoulses of group 2, while simultaneously or directly after group 3 is switched on. In FIG. 4 is an example of a setting of 66%, or 2/3 shown. This overlap can be adjusted until all nozzle rows 10 run at 100%, or 1 at the same time. As a result, the maximum cleaning effect is deployed. With three groups and an operating time of a group of less than 33.3%, or 1/3, there is a short break between the groups. However, this can already be sufficient for a light cleaning of, for example, very smooth surfaces and thus further reduce the air consumption. In an exemplary embodiment, there are 5 stages to which the drive time of 20%, 33%, 50%, 66% and 100% are incrementally assigned from 1 to 5. A stepless adjustment is also possible.

In a further embodiment, the time period that a group is driven is also set as a function of the grinding belt speed. As a result, a shorter pulse length for the individual groups could be sufficient given an increasing grinding belt speed.

In order to further increase the cleaning effect, which is greatly improved by the motion simulation, the nozzle assembly 8 itself may also be designed to be movable, as already mentioned above. However, such an oscillation of the nozzle assembly 8 can be much lower than in the prior art.

In a further preferred embodiment, a suction device 13 is provided around the nozzle assembly 8, which can absorb and carry away the dust which is blown by the abrasive belt 3.

Claims (14)

1. Belt blowing device (1) for a grinding unit (2) having a grinding device (3) for processing a workpiece (4), comprising:

   a nozzle arrangement (8) having a plurality of nozzles (12) for blowing out air and which is arranged transversely over the grinding device (3) with regard to its direction of travel (L) and is directed towards the grinding device (3), wherein the nozzle arrangement (8) comprises at least one pipe device which passes compressed air to the nozzles (12); and

   a control device which controls the blowing out of compressed air from the nozzle arrangement (8);

   characterised in that

   the nozzle arrangement (8) has several nozzle rows (10), and

   the control device is equipped to operate at least two nozzles rows (10) independently of one another so that a moving nozzle arrangement (8) is simulated.
2. Belt blowing device (1) according to claim 1, in which the control device is equipped to operate the individual nozzle rows (10) in a predetermined sequence, in particular one after another.
3. Belt blowing device (1) according to one of the preceding claims, in which the nozzle arrangement (8) is produced from an aluminium continuous casting profile or a plastic.
4. Belt blowing device (1) according to one of the preceding claims, further comprising a suction device (13) which is arranged in the region of the nozzle arrangement (8), preferably in at least one blowing out direction of the nozzles (12).
5. Belt blowing device (1) according to one of the preceding claims, in which the nozzle arrangement (8) or the belt blowing device (1) is arranged to be movable.
6. Belt blowing device (1) according to claim 5, in which the nozzle arrangement (8) or the belt blowing device (1) can be moved in a plane parallel to the plane of the grinding device (3), preferably in a direction parallel or vertical to the direction of travel (L).
7. Belt blowing device (1) according to claim 5 or 6, in which the control device moves the nozzle arrangement (8) or the belt blowing device (1) at a frequency of 0.1 Hz to 1.5 Hz, preferably at 0.5 Hz.
8. Belt blowing device (1) according to one of the preceding claims, in which the nozzles of the individual nozzle rows (10) of the nozzle arrangement (12) are at an angle, preferably so that the nozzles of the individual groups (G1, G2, G3) are at an angle alternately in opposite directions.
9. Belt blowing device (1) according to one of the preceding claims, in which the nozzle arrangement (8) or the belt blowing device (1) is aligned at an angle to the grinding device (3).
10. Belt blowing device (1) according to one of the preceding claims, in which at least two nozzle rows, preferably three or more, further preferably all, are offset by an equal distance (v).
11. Belt blowing device (1) according to claim 1, in which of the nozzle rows (10), at least two are offset with respect to one another.
12. Method for cleaning a grinding device (3) or a workpiece (4) using a belt blowing device (1), the belt blowing device (1) for a grinding unit (2) having a grinding device (3) for processing a workpiece (4) comprising:

    a nozzle arrangement (8) having a plurality of nozzles (12) for blowing out air and which is arranged transversely over the grinding device (3) with regard to its direction of travel (L) and is directed towards the grinding device (3), wherein the nozzle arrangement (8) comprises at least one pipe device which passes compressed air to the nozzles (12); and

    a control device which controls the blowing out of compressed air from the nozzle arrangement (8); wherein

    the nozzle arrangement (8) has several nozzle rows (10) of which preferably at least two are offset with respect to one another, and

    the control device is equipped to operate at least two nozzles rows (10) independently of one another, wherein the method has the steps:

    actuation of a first nozzle row (G1) so that air is ejected from the nozzles (12);

    completion of actuation of the first nozzle row, wherein at the same time or immediately thereafter, a second nozzle row (G2) is actuated so that a moving nozzle arrangement (8) is simulated.
13. Grinding unit having a belt blowing device (1) according to one of claims 1-11, comprising a grinding device (3) for processing a workpiece (4).
14. Processing machine having a grinding unit (2) according to claim 13, further comprising
    a conveying device (5) which transports workpieces (4) to the grinding unit (2) so that they may be processed there.

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