Machine tool and method for processing workpieces using a water jet

During the processing of workpieces using a water jet, standstill times or even operating interruptions arise on the machine tools when the processed workpieces are removed and the workpieces to be processed are positioned on the machine. This is made more difficult above all in water-abrasive jet cutting, which is known to be performed on immersed workpieces. Through a water basin, which may be flooded in a simple way and has a foldable side wall having lift-pivot cylinders on its front side, supports may be pushed into and out of the water basin. A loading station, having lifting devices, positioned behind the machine tool allows the preparation of workpieces while the machine tool executes a jet processing. The loading station having a linear drive allows the stacking of prepared supports. According to the method, the flooding of the water basin and the control of the foldable side wall are tailored to the loading station, through which a performance increase of the machine tool arises.

This application claims priority to a European application No. 03 405724.0 filed Oct. 9, 2003.

FIELD OF THE INVENTION

The present invention relates to a machine tool for processing workpieces using a high-pressure water jet and a method for operating a machine tool for processing workpieces using a high-pressure water jet.

BACKGROUND OF THE INVENTION

CNC machines using high-pressure water jet processing, particularly water jet cutting systems having one or more nozzles, are generally known. Thus, for example, a brochure (BYJET, undated) of the firm Bystronic Laser AG, CH-3362 Niederönz shows a universal cutting facility, suitable for pure water jet cutting and for abrasive jet cutting. A CNC-controlled cutting carriage movable over a water basin carries one or more cutting heads which are fed by high-pressure pumps having up to 4000 bar nominal output. Depending on the cutting agent (pure water jet or abrasive-water jet) the cutting is performed over the water surface or under the water surface. For this purpose, equalizing containers are provided which allow level regulation of the water bed and particularly function during loading and unloading of the cutting grate or grid.

This known machine has the disadvantage above all that during the loading and unloading, significant standstill times arise, which massively impair the overall output of the system.

Water jet processing is also increasingly used in mass production, and it has advantages in relation to laser processing, but in contrast thereto, no changes in the microstructure arise at the processing point. In addition, diverse materials, such as plastics and natural materials, foods, etc., can bear no or only a slight thermal stress, so that some advantages, such as performance and precision in laser processing, often do not come into consideration.

SUMMARY OF THE INVENTION

Is therefore the object of the present invention to provide a universal machine tool for water jet processing which allows a performance increase in relation to the machines used until now. In this case, reducing the standstill times of the machine is of special significance. The machine tool is not to take up any additional space in spite of easier charging and simplified unloading, i.e., the space provided for the preparation of loading and unloading is to be usable and easily accessible. The workpieces to be processed are to be positionable using existing and/or commercially available supply stations and the processed parts are to be transportable in the simplest way and/or be available directly for use.

This object is achieved by a machine tool for processing workpieces using a high-pressure water jet, the workpiece to be processed being mounted on a grate-like or grid-like support over or in a water basin, which is cuboid at least in the upper region, and has at least one water jet exiting from at least one nozzle applied to it. This nozzle is numerically controlled in its position at least in a horizontal plane (X, Y) and the distance between the workpiece and the nozzle is kept at least approximately constant or controlled in the vertical direction (Z) and an equalization container is provided in the region of the water basin, via which the level in the water basin is set. At least one side wall on the water basin is designed as partially raisable or foldable, and sliding elements, which allow a frame, having workpieces (W0, W1) positioned on its workpiece supports, to be moved in and out, are positioned on at least the fixed side walls adjoining this side wall.

The corresponding method for operating a machine tool for processing workpieces uses a high-pressure water jet, the workpiece to be processed being mounted on a grate-like or grid-like support over or in a water basin, which is cuboid at least in the upper region, and having at least one water jet exiting from at least one nozzle applied to it. This nozzle has its position numerically controlled at least in a horizontal plane (X, Y) and the distance between the workpiece and the nozzle is kept at least approximately constant or controlled in the vertical direction (Z), and an equalization container is provided in the region of the water basin, via which the level in the water basin is set. In a first method step, the water basin is filled to a lower level (N2). In a second step, with the side flap opened, a frame equipped with workpieces is introduced horizontally. In a third step, the flap is closed tight and the water is let into the water basin until a higher level (N1) results. In a fourth step, the water jet processing is performed. In a fifth step, the water is let out to the lower level (N2) and subsequently the flap is opened until it is in the horizontal setting. In a sixth step, the frame is moved horizontally out of the water basin. In a seventh step, a further frame equipped with workpieces is introduced horizontally into the water basin and the flap is closed tight again.

The raisable or foldable side wall of the present invention is advantageously a front wall having a closable rectangular opening (bulkhead). This opening is dimensioned in such a way that a frame having workpiece supports and workpieces located thereon may be pushed into and out of the water basin without problems manually or through a linear drive known per se.

In this way, completely processed batches (processing units) may be removed and unprocessed batches may be loaded back into the machine in less than two minutes. The standstill times of the machine tool are therefore multiple times shorter than, for example, with loading and unloading on location or if a hoist is used to raise and lower the frame in the water basin. A further advantage is the small space required for the whole and the accessibility during the charging and positioning of the workpieces.

The preparation work on the workpieces, such as placement and adjustment on the supports, is shifted out of the actual machine and may be performed conveniently, accessible from all the workpiece in the Z direction or are also CNC-controlled. sides, on a loading station, also known as a shuttle table.

The operating method according to the present invention is distinguished by its simple and easy-to-control sequence. It originates from a water jet processing machine known per se, whose cutting heads are controllable horizontally in the X, Y direction and either maintain a constant distance to the workpiece in the Z direction or are also CNC-controlled.

Preferred refinements of the object of the present invention are described further below.

Further frames having supports allow “bunkering” of prepared batches in a quantity which is arbitrary per se. Only a lifting device is provided for moving the frames in and out, which receives the frames having the particular processed parts at the correct height and/or provides the frames having unprocessed workpieces.

An equalizing container, which communicates with the water basin and may have a compressed air source applied to it, is mounted in or below the water basin and allows a space-saving arrangement for setting the water level in the basin.

The compressed air source may be a side channel compressor, which is especially advantageous for setting the water level, but its volume flow and pressure curve are ideally suited for driving water out of the equalizing container and therefore for setting the higher level in the water basin.

The attachment of a cleaning station that contains water nozzles and/or compressed air nozzles above the openable side wall is very efficient, since the processed parts may thus be washed and/or dried. This is especially advantageous in the case of abrasive processing procedures, since the processed parts are known to be contaminated with solid particles (garnet sand: Fe3Al2(SiO4)3; olivine: (Mg,Fe)2[SiO4]). The cleaning station allows their direct use and/or their packing without further cleaning procedures.

The use of the compressed air source used for setting the higher water level for blowing off and drying the processed parts is very economical, but this source is not used when the side wall is open, so that the air jet generated there may be conducted to compressed air nozzles connected to the compressed air source connected to the equalization container.

Besides numerous possibilities for pushing the frames having supports and workpieces in and out through linear drives, the use of a chain drive has especially proven itself. This drive is space-saving and may perform the necessary forward and backward movement on the frame economically via simple tappets.

The “driving out” of the water from an intermediate container into the water basin, wherein the upper level (N1) is set in the water container through a compressed air source connected to a closed equalization container and the lower level (N2) is set by turning this source off, may be operated very rapidly and economically; commercially-available level switches actuate a compressor which is used as the compressed air source. As soon as the compressor is switched off, the water flows back into the intermediate container; it then implements the level N3there again.

The cleaning method, wherein the processed workpieces are guided through a cleaning station as the frame is moved out and cleaned and/or dried using water and/or compressed air, is very economical and environmentally friendly. The water washed and/or blown off flows back into the water basin in this case; the solid particles possibly used do as well, so that both components are recirculated.

Stacked frames, possibly reaching up into the supporting frame, may ensure automated operation. It is only important that the height for introducing and removing the frames is approached reproducibly. The frames prepared for processing workpieces may be stacked one under another or one on top of another with their height adjustable. The loading and unloading of the workpieces per se may be performed using conventional means.

In a variation which is not shown, the individual frames are stacked one on top of another, rising above the machine tool, so that the lowermost frame is introduced into the water basin in each case. The finished processed parts are moved away on the same horizontal plane via the loading station in this case, before the next frame is lowered to the same height and introduced into the water basin.

In the following, the present invention is discussed in detail for exemplary purposes on the basis of a machine tool implemented for either abrasive or pure water jet cutting.

DETAILED DESCRIPTION OF THE INVENTION

InFIG. 1, a cutting facility for either pure water jet cutting or water-abrasive jet cutting is identified with1. A loading station2, also called a shuttle table, is placed adjoining and aligned thereto. A cooling device3, having insulated pipelines (not shown) is used for cooling the sensitive components of the facility1, particularly the high-pressure pump facility4placed next to it. An operating pressure of up to 4000 bar exists in the thin, metallic high-pressure lines6. These lines6are guided to a cutting bridge5, cf.FIG. 2, and supply cutting heads S1and S2with pressurized water there.

The cutting bridge5is constructed in a known way over a water basin9, and is linearly movable over its length. Electronics cabinets11, which also contain the computer for the CNC controller in addition to the power supply for all control and auxiliary devices, are located behind the water basin9. An operating station16, which is mounted on a stand15whose height is adjustable and also has a display screen, is positioned in front of the basin9.

Furthermore, a base frame2′ of the loading station2and lifting devices14band a discharge throat7for used solid particles are visible inFIG. 1.

The top view inFIG. 2additionally shows a mobile sand bunker12, which contains the clean solid particles necessary for the abrasive cutting. A fixed high-pressure line is identified with18and electrical channels are identified with19and20.

A catch container8for the slurry containing the solid particles, which is charged via a drag conveyor known per se and via the discharge throat7, is aligned on the face and to the central axis of the water basin9. The water basin itself is enclosed by a base frame9′. A support10for workpieces W1is located above the water surface—identified with H2O.

On the face of the water basin9diametrically opposing the loading station2, a foldable side wall22having associated lift-pivot cylinders is indicated.

The loading station2has, adjoining the cutting facility1, a chain drive21(drive motor having chain wheels). The supports10equal to the cutting facility1extend—as therein—over the entire surface and are implemented in the form of grating slabs, also known per se. Workpieces W0intended for processing are laid on these grating slabs and are also clamped, depending on the object.

Three lifting devices14aand/or14b, which are in turn coupled to one another by three mechanical connections14′, are attached diametrically opposing the actual shuttle table of the loading station2. This is symbolized by a dot-dash line. In addition, the three cylinders of the lifting devices14aand14bare hydraulically coupled, so that the frames of the supports10may have their heights adjusted absolutely parallel.

FIG. 3shows the inside of the water basin9of the machine1having its associated equalizing basin34, which is separated therefrom via walls33; three water levels N1through N3are shown.

The cutting bridge5having its known components such as equalizing cylinders26, individually controllable cutting heads S1and S2, a line duct28for power and signal supply of the cutting bridge5, and an expansion bellows27, also typical, are mounted on the base frame9′. The equalizing cylinders26are used, as is also known, for weight equalization in the Z direction.

Slide rails100are indicated in the water basin9, above its highest level N1, attached around the edge to diametrically opposing fixed side walls35. Cutting nozzles29having well-known height scanners30, illustrated here in the operating position, are also shown.

A pressurized air source, a commercially available side channel compressor101(Ernst Häusermann & Co. AG, CH-8010 Zurich: two-stage side channel compressor of the type DORA SAP 300) is placed on the bottom left side, beside the facility1. Outgoing feed lines N and R are indicated by arrows. Line N is guided to a connection31of an air supply line31′. The compressed air exiting from the supply line31′ increases the air cushion existing in the equalizing container, through which the water present here flows out via ascending pipes32in the direction of the arrow via the cover32′ into the water basin9. The water level may thus be set at the preselected height N1in a simple way—with throttle valves interposed. The cover32′ is used as a slurry protection and only has lower slots for the water to flow through; see arrows.

In order to lower the water to the level N2, the pressure source101is switched off, through which the water flows back and finally the level N2or N3results. In this time, the pressure source may be switched over and guided via the second line R to a cleaning station to be discussed later.

FIG. 4shows the loading station2in the center, which supplies the workpieces W0to be processed by a pivot lift or60having a gripper61, via vacuum bell jars62. The chain drive21, the base frame2′, guide rollers43, and side jaws48are visible here. Floor plates17, which allow the operating height to be equalized to the machine tool1, are also visible.

It may be seen fromFIG. 4athat the rollers43are mounted on the base frame2via a roller support45so they are rotatable. A profiled slide rail46engages on the rollers43, which carries a frame42,42′ via first side jaws47, in which grating slabs are suspended that are used as the supports10.

On the diametrically opposing side, seeFIG. 4b, the rollers are dispensed with, the frame42,42′ is attached here to second side jaws48and slides on profile49.

The support10, the grating slabs, includes a stirrup frame38having suspension wings36and projecting cams37. The actual support is a reinforced rubber lip39which is inserted replaceably into the frame38.

FIG. 6shows the end region of the water basin9in simplified form: one may again see rollers43and the frames42running thereon here, as well as lower guide rails44. A cleaning station40, which contains water nozzles41and air nozzles50, is installed above the water basin9at the end.

The water nozzles41are connected to the fresh water; they are actuated as the frame42is moved out and wash off abrasive material and/or material removed from the workpieces from the finished parts.

The air nozzles50are fed by the pressure source101and additionally dry off the parts. The water flowing off of the parts falls back into the water basin9.

FIGS. 7athrough7cshow details on moving the frame42in and out with its supports. The first side jaws47having rollers43and an angled pushrod51, which engages on a tappet54via a recess52as shown inFIGS. 7band7c, are visible here. This tappet54is placed on a chain link55, which in turn runs over chain wheels53.

The chain links55form an endless chain, over which drive21is guided, cf.FIG. 2. The chain drive21moves the frame42with its supports into the water basin9,FIG. 2, and may move it back out again, into the position shown inFIGS. 7aand7b, by switching over the rotational direction of the drive21.

The illustration inFIG. 8shows the closing mechanism of the foldable side wall22and is constructed like a “bulkhead”. The water basin9is terminated on its face by the side wall22(Pos.1), which has a bearing22ain its upper region and allows the part22′—a flap—to tilt by 90°. A hydraulic cylinder57, which is held at its end on a lower joint58so it is rotatable and engages using its pushrod (via a joint pin) on the flap22′ at an angle22″, is used as a drive.

The opened position of the flap22′ is shown thin and marked as Pos.2; the corresponding positions of the pushrods are identified with59′ and those of the hydraulic cylinder with57′.

For reasons of illustration, showing the necessary sealing elements was dispensed with; the very simply constructed level setting having adjustment screws13and an adjustable support24may be seen in the lower region of the water basin.

The object of the present invention is, of course, also suitable for multiaxis and other processing procedures.

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