Single shaft chip crusher, chip processing machine, and method of crushing chips

Abstract

A self-feeding chip crusher is provided, which includes a rotatable shaft (12) with a plurality of protrusions (13), a crusher element (17), and a crushing zone (16) between the rotatable shaft (12) and the crusher element (17), in which chips are configured to be crushed, and wherein more than 120° of the rotatable shaft (12) is exposed to chips added to the chip crusher. There is further provided a method of using the chip crusher comprising reuse of cutting fluid. The energy efficiency is improved and it is possible to efficiently reuse cutting fluid.

Description

[0001] SINGLE SHAFT CHIP CRUSHER, CHIP PROCESSING MACHINE, AND METHOD OF CRUSHING CHIPS

[0002] TECHNICAL FIELD

[0003] The present invention relates in general to a self-feeding chip crusher and a chip processing machine including such a chip crusher.

[0004] BACKGROUND

[0005] In the field of metal working and processing, chips / tumings / shavings of various sizes, also referred to as metal swarf, are created as a result of different machining operations, such as milling, turning, or the like. The chips are often bulky and voluminous. In particular, they tend to take up a large space during intermediate storage as well as in transportation to a recycling station. This is clearly inefficient since an unnecessary amount of transport vehicles are involved in this transportation.

[0006] Attempts have been made to provide arrangements that have the purpose of reducing the size of the chips and thereby their volume. However, these so called chip reducers often suffer from several drawbacks. For instance, they are associated with having high tolerance levels, which makes them especially sensitive to wear.

[0007] US 20020175234 Al describes a chip reducer comprising a shearing shaft having protrusions in the form of shearing cutters with a certain sharpness, which are configured to engage between shearing teeth of two shearing rows. As the shearing shaft is rotated, chips fed into the apparatus are cut through engagement by the cutters and teeth. This interaction between the cutters and teeth requires relatively high tolerance levels, which makes this apparatus more sensitive to wear.

[0008] Furthermore, some of the proposed chip reducing arrangements are not able to reduce the size of long and stringy chips. From the above, it is understood that there is room for improvements.

[0009] There is, therefore, interest for development of self-feeding, sturdy apparatus suitable for processing chips of various sizes, including long and stringy. SUMMARY

[0010] An object of the present invention is to alleviate at least some of the problems related to prior art. This object is achieved by means of the technique set forth in the appended independent claims; preferred embodiments being defined in the related dependent claims.

[0011] In a first aspect, a self-feeding chip crusher is provided, which includes a rotatable shaft with a plurality of protrusions, a crusher element, and a crushing zone between the rotatable shaft and the crusher element in which chips are configured to be crushed and wherein more than 120° of the rotatable shaft (12) is exposed to chips added to the chip crusher.

[0012] The crusher is self-feeding because of the protrusions that make the chips entangle on the rotatable shaft and in each other so that the chips are drawn into the device.

[0013] The rotatable shaft is exposed to chips which are intended to be fed into the device. The exposure of at least 120° is determined when looking from a point on the extension of the axis of the rotatable shaft in the direction along the along the center axis of the rotatable shaft. This view is depicted in Fig 7, i.e. looking at the rotatable shaft from the side. The angle is drawn from the center of the rotatable shaft. No obstacles are around the more than 120° of the rotatable shaft. Although not realistic, 360° exposure would mean that the entire rotatable shaft is exposed, i.e. no obstacles are around the rotatable shaft. Obstacles are defined in relation to chips intended to be added to the device. Exposure to chips added to the chip crusher means that no obstacles are in the way for the added chips to reach the rotatable shaft. Then the rotatable shaft is exposed to chips intended to be added to the chip crusher to a degree of more than 120°. This is determined for chips intended to be added to the crusher during operation of the device. In one embodiment more than 140° of the rotatable shaft is exposed. In one embodiment more than 160° of the rotatable shaft is exposed. In one embodiment more than 180° of the rotatable shaft is exposed. In one embodiment more than 200° of the rotatable shaft is exposed. In one embodiment more than 220° of the rotatable shaft is exposed. In one embodiment more than 240° of the rotatable shaft is exposed. The exposure of the rotatable shaft together with the protrusions give a selffeeding effect because of the entanglement.

[0014] The simple design of the self-feeding chip crusher makes it easy to produce, and at a low cost. Moreover, thanks to low tolerance levels, it is particularly resistant to wear in comparison with prior art arrangements that cut chips instead of crushing them (see, for example, US 20020175234 Al). It has turned out that crushing the chips instead of cutting them reduces the overall energy consumption and thereby the total environmental and carbon footprint, in particular in long term use, since cutting devices tend to use much more energy after a while as the cutting tools get less sharp.

[0015] Furthermore, the chip crusher design makes it possible to reuse liquids including for instance cutting liquids, cooling liquids and process liquids which are present on the chips to be crushed. This gives environmental advantages as well as a reduced carbon footprint.

[0016] Also, the chip crusher according to the present invention is beneficial in that it can reduce the volume of chips to be crushed several times their original volume, such as up to about ten times their original volume.

[0017] In an embodiment, the rotatable shaft is elongated and configured to rotate about a rotational axis. This is beneficial in that, as the shaft rotates, chips can be crushed against the crusher element as well as against each other.

[0018] In yet an embodiment, the crusher element extends in parallel to and is arranged at a predetermined distance from the rotatable shaft. This way, a stable construction of the self-feeding chip crusher is provided.

[0019] In a further embodiment, the protrusions protrude radially outwards from an outer circumference of the rotatable shaft. Preferably, the protrusions protrude along the length of the rotatable shaft. More preferably, the protrusions are dispersed along the whole length of the rotatable shaft, such as in a randomized pattern. This is beneficial in that the chips may be entangled on the shaft and more easily crushed against each other as well as in the crushing zone. In particular the chips are entangled on the shaft and thereby the device becomes self-feeding since the chips typically are entangled in each other as well so that all entangled chips are drawn into the rotatable shaft. In an embodiment, the self-feeding chip crusher further comprises a frame that includes the crusher element. Advantageously, the frame upholds the structural integrity of the self-feeding chip crusher.

[0020] In yet an embodiment, the frame further includes at least one supporting member. The at least one supporting member contributes to the self-feeding function of the chip crusher by entangling uncrushed chips on the rotatable shaft for further crushing. Furthermore, the at least one supporting member serves the function of supporting the crusher element on the frame to create a robust structure for the chip crusher.

[0021] In a further embodiment, the at least one supporting member is inclined with respect to the crusher element, which helps in supporting the crusher element. Preferably, the at least one supporting member extends in parallel to the rotatable shaft. This is advantageous to create support over the whole length of the rotatable shaft.

[0022] In a second aspect, a chip processing machine is provided, which includes the self-feeding chip crusher according to the above. A chip processing machine of this kind preferably includes a press chamber for compacting crushed chips into blocks for convenient storage and transport.

[0023] In an embodiment, the chip processing machine further includes a housing with an opening for receiving the chips to be crushed.

[0024] In yet an embodiment, the chip processing machine further includes at least one stir plate, which is beneficial in cases where chips get trapped on inner walls of the housing. The stir plate moves during operation. Thanks to the at least one stir plate, chips may be stirred so that they are pushed down to the crushing area of the chip processing machine, which is where the self-feeding chip crusher according to the above is located.

[0025] In a yet further embodiment, the chip processing machine further includes a cutter housing comprising a drive motor and a miller screw, wherein the cutter housing may have internal spiral grooves. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] By way of example, embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

[0027] Fig. 1 is an isometric view of a chip processing machine according to an embodiment,

[0028] Fig. 2 is a top view of the chip processing machine of Fig. 1,

[0029] Fig. 3 is a side view of the chip processing machine of Fig. 1 and 2,

[0030] Fig. 4 is an isometric view of a chip processing machine according to another embodiment,

[0031] Fig. 5 is an isometric view of a chip crusher,

[0032] Fig. 6 is a side view of the chip crusher of Fig. 5, and

[0033] Fig. 7 is a cross-section view of the chip crusher of Fig. 6 as viewed along the line VI- VI.

[0034] Fig. 8 is an isometric view of the cutter housing 23 comprising the drive motor 24, the miller screw 25, the cutter plate 26 and the tilt cylinder 28.

[0035] DETAILED DESCRIPTION OF EMBODIMENTS

[0036] A chip processing machine 1 will now be described in relation to Figs 1-3. An overall purpose of the chip processing machine 1 is to receive chips from turning or milling processes, crush them into smaller fragments, and finally press them into compacted blocks that are more conveniently transported and stored. The chips fed into the processing machine 1 may be metal chips of materials such as steel, brass or aluminum. Other types of materials that can be processed by the chip processing machine 1 is wood, plastic or composite materials.

[0037] For the avoidance of doubt, crushing according to the present application refers to the act of changing the shape of the chips and / or breaking them into smaller fragments. Chips may be crushed multiple times in the crushing zone as well as against each other.

[0038] Chips fed into the chip processing machine 1 may also be referred to as turnings, filings, shavings, or swarf. In any case, they result from different machining processes. The chips may come in various shapes and forms. For instance, they may be in the shape of particles in the range of a few millimeters, hereby referred to as short chips. Alternatively, the chips may be in the form of long and stringy tendrils, hereby referred to as long chips. Advantageously, the chip processing machine 1 is able to process both short chips and long chips.

[0039] The chip processing machine 1 includes a housing with an opening 2 through which chips are to be fed. In particular, the opening 2 is rather funnel-shaped for the chips to be guided towards the crushing area of the chip processing machine 1. In Figs 1-4, two stir plates 3, 4, also referred to as stir plates, are usable to shake chips that have gotten stuck on the insides of the opening 2 into falling downwards to the crushing area. The stir plates 3, 4 are particularly useful for shaking down short chips. Preferably, the stir plates 3, 4 are actuated by an actuator, such as a hydraulic cylinder or the like. There may be only one stir plate, or more than two stir plates, such as three, four or five stir plates in the chip processing machine 1.

[0040] A feed screw 5 is provided downstream of the crushing area, at the bottom of the funnel-shaped opening 2. The feed screw 5 is adapted to feed crushed chips into a cutter housing 23. In the cutter housing 23 the material further worked and fed into a press chamber 6 located downstream of the crushing area. The press chamber 6 may also be referred to as a compactor since its purpose is to produce blocks of compressed fragmented chips. The chip processing machine 1 further includes an outlet pipe 7 through which the produced blocks are to be ejected.

[0041] The chip processing machine 1 may further comprise a cutter housing 23 comprising a drive motor 24, which may be electric or hydraulic, and a miller screw 25, i.e. a screw providing both a cutting action and a transporting action for items (such as those having been crushed). The miller screw 25 shreds, or cuts, the items (e.g., crushed chips) into acquired sizes against a cutter plate 26 fastened to the cutter housing 23. Chips in the desired size are then forced in the axial direction of the miller screw into the press chamber 6. The miller screw 25 turns the items (e.g., crushed chips) into further finely distributed fragments of more homogenous sizes prior to pressing, leading to high-quality end results exceeding those known in the arts. In addition the miller screw 25 makes it possible to recycle cutting fluid and other fluids to a particular high degree. For the avoidance of doubt, the term ‘a cutting action’ refers to dividing pieces with sharp-edged tools or objects, including trimming or reducing the length by using a sharp implement.

[0042] The cutter housing 23 may have internal spiral grooves. Said grooves may improve the volume capacity and at least to some extent prevent chips from co-rotating with the miller screw 25. This may provide improved volume capacity and capability to efficiently preload the press chamber 6.

[0043] The cutter housing 23 may further comprise an opening 27. If any chip, such as a crushed chip, and / or fragment block the miller screw 25, a tilt cylinder 28 may rotate the cutter housing 23, such that they will not be engaged by the miller screw 25 and the cutter plate 26 and hence be rejectable, e.g. by the force of gravity once the cutter housing 23 has rotated such that the opening 27 points downwards. After the chip and / or fragment has been ejected, the cutter housing 23 will be rotated back to its original position and the process can continue.

[0044] One way of monitoring that a chip and / or fragment has become stuck in the miller screw 25 and / or cutter housing 23 is to monitor the torque applied by the drive motor 24. This monitoring of the torque could be achieved, for example, by monitoring the drive current to the drive motor 24. If the applied torque exceeds a certain threshold value, the above sequence for rejecting a stuck item may be implemented.

[0045] It is advantageous to be able to tilt, or rotate, the cutter housing 23 if an item has become stuck and blocks the miller screw 25. It is also possible to reverse the direction of the miller screw 25 in order to release the too large item having become stuck. Preferably, the feed screw 5 is shut off prior to the cutter housing 23 being rotated in case of a stuck item requiring removal. In one embodiment the cutter housing 23 is adapted to rotate about 100°.

[0046] In another embodiment, there is no tilt cylinder 28 provided for rotating the cutter housing 23; instead, the rotation of the cutter housing 23 is achieved by providing the housing 23 on bearings 29 allowing for rotation and a locking system enabling the cutter housing 23 to be locked in desired positions. If an object has become stuck, the locking system may release the cutter housing 23. Thereafter, the miller screw 25 is rotated in the cutting direction, bringing the cutter housing 23 with it. Once the cutter housing 23 has reached the desired position, the cutter housing 23 is locked and the miller screw 25 is rotated in the opposite direction, i.e. the direction releasing the stuck item, such that the stuck item may be rejected.

[0047] In one embodiment, the processing machine comprises a feeding device, which feeds chips to be crushed from a CNC machine. Examples of feeding devices include but are not limited to a conveyor, and a mechanical arm. A CNC machine is a computer controlled machine (computer numerical control) which is used to process objects. In one embodiment the object is a metal object so that metal chips are treated. Examples of a CNC machine includes but is not limited to a drill, a lathe, a milling cutter. In one embodiment the CNC machine is at least one selected from a a drill, a lathe, and a milling cutter. Preferably the processing machine is placed close to the CNC machine so that the chips easily can be fed directly to the crusher without intermediate storage or handling. In one embodiment, there is a screen filter and a pump adapted to pump cutting fluid from the chip processing machine according to the invention to a CNC machine.

[0048] An another aspect there is provided a method of crushing chips wherein the chip processing machine described above is used and wherein the method comprises the steps of: a) feeding chips to the device, and b) collecting crushed chips form the device.

[0049] In one embodiment of the method the chips are fed from a CNC machine to the device with a feeding device without intermediate storing and wherein a liquid is collected and fed back to the CNC machine. If the chips are fed directly fed to the crusher, then it is possible to reuse coolant / cutting fluid used in a CNC machine such as a drill, a lathe, or a milling cutter.

[0050] In such a CNC machine, when used for metal working a cutting fluid is typically used, which cutting fluid is an emulsion comprising water and a hydrophobic substance such as an oil. When the chips are stored the water in the emulsion evaporates leaving behind either a pure oil phase or an emulsion with less water. When water has evaporated partially or completely, the emulsion cannot be reused anymore and the oil has to be recycled at a certain cost. Further the oil remaining on the chips may make it more difficult to recycle the chips.

[0051] If the cutting fluid is recovered directly it is possible to reuse it so that it is filtered and pumped back to the CNC machine, which is a great benefit both from an economic and an environmental perspective.

[0052] When crushing chips with cutting fluid from for instance a lathe are left to drip of, only a minor part of the cutting fluid can be recovered as evident from the appended examples. When using the present invention is possible to reuse a much higher fraction of the cutting fluid, up to 99 wt%. Without wishing to be bound by any particular theories the inventor believes that two effects contribute to this. A) the rotatable shaft, where chips are entangled and crushed against each other which gives a scraping effect so that cutting fluid is removed from the chips. B) The optional cutter housing 23 with the miller screw 25, where the pieces of material are further scraped and pressed against each other so that further cutting fluid is removed. In the final stage the material is pressed so that additional cutting fluid is removed.

[0053] It is important that the chips are processed without too much delay and preferably directly from the CNC machine. If the there is a delay before the treatment in the crusher according to the invention a part of the water in the cutting fluid will evaporate leaving a much more viscous liquid which is more difficult to remove.

[0054] The chip processing machine 1 shown in Figs 1-3 may also be referred to as a raptor. In particular, it is a raptor with central usage, meaning that the chip processing machine 1 may be free-standing and fed, independently, by any kind of separate feeding mechanism. To this end, the chip processing machine 1 has a cover plate 8 which is pivotally connected to the housing. The cover plate 8 may assume an extended position and a retracted position. Only the extended position is shown in Figs 1-3. However, an arc-shaped guiding groove is shown, which implies that the cover plate 8 may be retracted as well. The extended position is favorable in that feeding of chips is simplified since a larger opening 2 is created. In contrast, the retracted position is favorable in cases where feeding may be put to a halt.

[0055] A similar type of chip processing machine 1 as described in relation to Figs 1-3 is shown in Fig. 4. In contrast, the chip processing machine 1’ of Fig. 4 is a raptor with an integrated function, meaning that the chip processing machine 1 ’ may be integrated in, or part of, an external chip producing apparatus 20, such as an CNC (computer numerical control) machine.

[0056] In one embodiment the self feeding chip crusher is integrated in, or part of, an excavator (not shown).

[0057] The chip producing apparatus 20 may also be referred to as a chip supplier 20. In this case, the cover plate 8 shown in Figs 1-3 is removed to leave a larger opening 2, which in turn enables the chip processing machine 1’ to be more easily integrated with the external chip supplier 20. In Fig. 4, the chip supplier 20 is illustrated as having a chip supply chamber 21. Chips are delivered from the chip supply chamber 21 to the chip processing machine 1’ via a transfer element 22, such as a conveyor belt. Since the chips are delivered directly to the crushing area of the chip processing machine 1’, there is no need for stir plates 3, 4 in the chip processing machine 1’ shown in Fig. 4.

[0058] Apart from the cover plate 8 and the stir plates 3, 4, the chip processing machine 1’ shown in Fig. 4 contains all features of the chip processing machine 1 shown in Figs 1-3. It is clear that the cover plate 8 is beneficial since it enables transformation of the chip processing machines 1, 1’ from central usage to integrated usage by simply adding or removing the cover plate 8.

[0059] In the crushing area of the chip processing machine 1, 1’ shown in Figs 1-4, a chip crusher 10 is shown, which will now be described in more detail in relation to Figs 5-7.

[0060] Fig. 5 illustrates the chip crusher 10 which is configured to crush the chips fed into the chip processing machine 1, 1’. The chip crusher 10, which may also be referred to as a shredder, includes a rotatable shaft 12 having a plurality of protrusions 13 on its outer circumference. The rotatable shaft 12, hereby referred to as shaft 12, is rotatable about a rotation axis A, which in turn corresponds to a longitudinal axis A of the chip crusher 10. Moreover, the shaft 12 is elongated and has a substantially cylindrical shape. The chip crusher 10 also includes a frame 11, which is built up by several parts, including for instance a bearing 14, and preferably also a crusher element 17 as well as supporting members 18, 19 therefor (see Figs 6 and 7). The shaft 12 may be described as having a length extending between the ends of the shaft 12, i.e. between the end plates numbered 11 in Fig. 5. As shown in, for example, Figs. 1 and 2, the chips crusher 10, may extend across the width of the chip processing machine, such as across the width of the opening 2.

[0061] The chip crusher 10, may also contribute to feeding the feed screw with chips, such as crushed chips, which in turn feeds the press chamber 6, or the miller screw 25 (when applicable).

[0062] Moving on to Fig. 6, the chip crusher 10 is illustrated from a side view. The protrusions 13 protrude radially outwards from the outer circumference of the shaft 12, along the longitudinal axis A of the chip crusher 10. Put differently, the protrusions 13 project in a direction substantially perpendicular to the rotation axis A of the shaft 12. In particular, the protrusions 13 protrude along the length of the shaft 12. In particular, the protrusions 13 form part of a rugged surface of the shaft 12. A main purpose of the protrusions 13 is to entangle and crush chips against each other, as well as against the crushing element 17. The entanglement makes the crusher self-feeding. As shown in the drawings, the protrusions 13 are shaped as knobs. Therefore, the protrusions 13 will in the following be referred to as knobs 13. Other shapes are feasible, as long as they have a crushing ability.

[0063] The chip crusher 10 includes the crusher element 17, which may also be referred to as a crusher plate 17, a crushing plate 17, or a crushing element 17. As illustrated in Fig. 6, the crusher plate 17 is elongated and extends in parallel to the shaft 12, along the longitudinal axis A of the chip crusher 10. Furthermore, the crusher plate 17 extends perpendicularly with respect to the longitudinal axis A of the chip crusher 10. The crusher plate 17 is also substantially planar, having a crushing edge facing the shaft 12 (see Fig. 7), configured to crush chips. The crusher edge may be substantially smooth facing the surface of the shaft 12. Preferably, the crusher plate 17 is configured to act as a counter plate or a counter steel. Moreover, the crusher plate 17 is arranged at a predetermined distance from the shaft 12, and in particular at a predetermined distance from a center core of the shaft 12.

[0064] As illustrated by the dark boxes 16 in Fig. 6, the distance between the crusher plate 17 and the shaft 12 differs along the rotation axis A. This is because the crusher plate 17 is stationary during use, whereas the shaft 12 is configured to rotate about the rotation axis A. Due to the provision of knobs 13 on the surface of the shaft 12, these knobs 13 will sometimes be closer to the crusher plate 17, or further away from the crusher plate 17, than neighboring knobs 13 along the longitudinal axis A of the chip crusher 10.

[0065] The dark boxes 16 represent the area in which the chips are to be crushed, which will hereby be referred to as a crushing zone 16. This crushing zone 16 is located between the shaft 12 and the crusher element 17. In Fig. 6, the higher the dark box is, the bigger the distance is between the crusher plate 17 and the shaft 12. Conversely, the shorter the dark box is, the closer the shaft 12 is to the crusher plate 17.

[0066] In general terms, the crushing zone 16 represents a gap between the shaft 12 and the crusher plate 17. The crushing zone 16 may be described as an area in which the crusher plate 17 is adjacent to the shaft 12 including the knobs 13. In use, when the shaft 12 is rotating, this gap enables the chips to get crushed towards the crusher plate 17. Furthermore, the gap enables the chips to get crushed against other chips. This way, the gap reduces the wear on the different parts of the chip crusher 10. As a non-limiting example, the gap between the crusher plate 17 and the shaft 12 may be in the order of one tenth of a millimeter to tens of millimeters 0.2 - 8 mm, such as 0.3 - 8 mm for instance about 0.5 mm such as 0.2 - 0.8 mm, such as 0.3 - 0.8 mm.

[0067] The rotatable shaft 12 is driven by a motor 15, such as an electric or hydraulic motor. Preferably, the chip crusher shaft 12 is rotatable both clockwise and counterclockwise. The direction of rotation is determined based on the (hydraulic) pressure exhibited on the shaft 12 as the chips are crushed in the crushing zone 16. For example, once the pressure exhibited on the shaft 12 is high, such as in the occasion that chips get stuck or somehow lead to blockage, then the shaft may counter-rotate and resume its rotation. As mentioned, the knobs 13 protrude radially outwards from the shaft 12. The shaft 12 may be considered as being divided into a number of concentric, substantially circular-shaped segments abutting each other, side by side, in the direction of the longitudinal axis A. Preferably, a number of knobs 13 are provided and spaced equidistantly from each other in each segment. The segments may be separate and joined together for instance by welding. Alternatively, the shaft 12 may be molded as one unit without requiring joining of separate segments. To enable efficient winding and entanglement of chips on the shaft, the knobs 13 exhibit a randomized pattern along the shaft 12, in the direction of the rotation axis A.

[0068] Fig. 7 illustrates a cross-section of the shaft 12 shown in Fig. 6, where three knobs 13 are spaced equidistantly apart from each other along the outer circumference of the shaft 12. There may be less than three knobs, such as one knob or two knobs in each segment of the shaft 12. Alternatively, there may be more than three knobs in each segment of the shaft 12, such as four, five or six knobs. In Fig. 7, the crushing zone 16 is indicated by a dotted area, indicating that the crushing zone 16 is rather a volumetric space in which the chips are crushable, rather than a sharp edge against which chips are sliced or cut. As can be seen, the crushing zone 16 is delimited by the distance between the crusher plate 17 and the shaft 12, as well as the tilted supporting members 18, 19 provided on the frame 11.

[0069] The supporting members 18, 19 are shaped as longitudinally extending plates (see Figs 5 and 6) that are inclined with respect to each other. In particular, the supporting members 18, 19 are angled with respect to the crusher plate 17. Together, the supporting members 18, 19 are angled by a respective angle a to form a tip which is directed towards the center core of the shaft 12 (marked by a dot in the center of the shaft 12 in Fig. 7). More specifically, the supporting members 18, 19 are in abutment with the crusher element 17. Optionally, the supporting members 18, 19 may be referred to as being angulated.

[0070] There are several advantages associated with the inclination of the supporting members 18, 19 with respect to the crusher plate 17. For instance, the supporting members 18, 19 support the crusher plate 17 in a way such that the crusher plate 17 can resist the power exerted on it by the crushing of chips. Furthermore, the supporting members 18, 19 may act as sliding members so that deflected chips that have been crushed can be directed to the area of the feed screw 5 (see Figs 1-3).

[0071] More importantly, the supporting members 18, 19 may be considered as guiding plates. They contribute to a self-feeding mechanism of the chip crusher 10 by guiding partially crushed chips back into the crushing zone 16 for further crushing. During use, chips located in vicinity of the crushing zone 16 tend to be pushed back into the crushing zone 16, and onto the rotating shaft 12 as a result of a high-pressure zone that is created in the crushing zone 16. Put differently, as the chips arrive in the crushing zone 16, the angulation of the supporting members 18, 19 creates a force that draws the chips into the crushing zone 16. In the crushing zone 16, the chips may be pressurized both between the knobs 13 and the crushing plate 17, but also against other chips. The pressure exerted on the chips leads to the crushing of the chips.

[0072] Chips that have been crushed and are small enough to pass through the gaps in the crushing zone 16 proceed downstream through the chip processing machine 1, 1’, more specifically into the area of the feed screw 5 for further transport into the compactor 6 (see Figs 1-3). Conversely, chips that have not diminished enough in size will be pulled into the crushing zone 16 towards the crushing plate 17 by means of the supporting members 18, 19, i.e. the chips will be self-fed back into the chip crusher 10, and wound on the rotatable shaft 12 with help of the knobs 13. The chips may be turned several times around the shaft 12 before they reach the crusher plate 17 for crushing into smaller fragments. Thus, depending on the dimension of the chips, the redirected chips may have to pass through at least one rotation cycle of the shaft 12 before re-entering the crushing zone 16. In some cases, the chips are even crushed against each other before they are rotated down to the crushing zone 16. Moreover, long chips tend to tangle up by themselves. Thus, when long chips get tangled up on the shaft 12, the shaft 12 pulls all long chips in a direction towards the center of shaft 12. This behavior also forms part of the self-feeding mechanism of the chip crusher 10.

[0073] The flatter the angle a of the supporting members 18, 19, the more self-feeding of chips is achieved for the chip crusher 10. Explained differently, the drawing force against the crusher plate 17 is comparatively higher in the crushing zone 16 for a relatively flatter angle a than if the angle a were more acute. Preferably, the supporting plates 18, 19 extend in parallel to the rotatable shaft 12, in the direction of the longitudinal axis A. The supporting members 18, 19 need not be plate shaped, as long as they fulfil their purposes of self-feeding and supporting of the crusher plate 17 as described above.

[0074] Fig. 8 illustrates an isometric view of the cutter housing 23 comprising the drive motor 24, the miller screw 25, the cutter plate 26 and the tilt cylinder 28. The motor is placed on one end of the cutter housing 23 and drives the miller screw 25.

[0075] The crushing ability of the chip crusher 10 is based on the principle that the crusher unit 10 has an open design in which chips can move freely around the shaft 12. As the shaft 12 rotates, chips get tangled up on the rotatable shaft 12. The knobs 13 contribute to the entanglement and to drawing of the chips into the crushing zone 16 where the chips are crushed against the crusher plate 17. As mentioned, the chips may as well be crushed against each other along the shaft 12, which reduces the wear on the chip crusher 10. Thus, the chip crusher 10 is self-feeding without the need for external equipment, thanks to its open design.

[0076] As mentioned above, the chip crusher 10 possesses low tolerance levels, i.e. loose tolerance compared to a cutter. In prior art apparatuses, such as those of the cutting type, high tolerance, i.e. tight tolerance or strict tolerance is necessary so that the process and / or apparatus do not stop functioning. In the present application, however, high tolerances are not necessary. One reason for this is believed to be due to the gap between the crusher element 17 and the rotatable shaft 12 in the crushing zone 16, where the gap provides that these parts are not impacting or colliding into each other, reducing the wear on the different parts of the chip crusher. A certain torsion twist along the rotatable shaft 12 may also be tolerated as the outer diameter of the protrusions 13 do not collide into the crusher element 17 due to the gap. Low tolerance levels may also be referred to as ‘loose tolerance’.

[0077] For the avoidance of doubt, the term ‘open design’ refers to a design where at least one side is open. Preferably, two circumferential sides or more are open. This design is believed to lead to higher exposure to chips, making it easier for the shaft to entangle further chips (of any size) and / or for chips, such as those already entangled on the shaft, to entangle with further chips. This design is also believed to contribute to the low tolerance levels obtained. This design is further believed to contribute to the selffeeding mechanism of the invention.

[0078] For the avoidance of doubt, the term ‘self-feeding’ refers to the ability where there is less and / or no need for actively (either manually or automatically) feeding chips to the crusher. In other words, the term refers to a process where the crusher is feeding itself with chips with less and / or no external interference.

[0079] Moreover, the chip crusher 10 according to the above may be considered to provide a passive crushing of chips. This is in contrast to prior art suggestions where chips are immediately cut, actively, by a cutter. By having a passive crushing of the chips, a comparably larger amount of chips may be fed into the chip processing machine 1, 1’, where uncrushed chips are eventually self-fed into the chip crusher 10. This is less energy-consuming than having to actively feed and cut chips.

[0080] From a commercial point of view, the chip crusher 10 according to the above may be sold separately or in conjunction with the chip processing machine 1, 1’. In the drawings, only one chip crusher 10 is shown in relation to the chip processing machines of Figs 1-4. It is appreciated that it may be feasible to provide a chip processing apparatus that contains more than one chip crusher 10 of the type described above.

[0081] In summary, the chip crusher 10 is self-feeding, meaning that the gap 16 in relation to the knobs 13, provides an efficient self-feeding mechanism for the chip crusher 10, whereby chips can be crushed against the crusher plate 17 as well as against other chips. Both long and stringy chips as well as shorter chips can be crushed, or fragmented, in the chip crusher 10. The supporting member 18, 19 contribute to the selffeeding mechanism of the chip crusher 10 in that they force chips to get tangled around the shaft 12, between the knobs 13, as well as in between the knobs 13 and the crusher plate 17. Moreover, a good grip is achieved as chips are rotated in between the knobs 13. Furthermore, new chips are efficiently fed into the crushing zone 16 by the open deign of the chip crusher 10.

[0082] Examples

[0083] Example 1 (comparative, not according to the invention) Chips from a lathe with cutting fluid were left to drip off. It was measured that approximately 20 wt% of the cutting fluid dripped off and was possible to reuse.

[0084] Example 2

[0085] When chips from a lathe with cutting fluid as in example 1 were treated in a device according to the present invention the cutting fluid was possible to reuse to about 99 wt%. The chip processing machine according to the invention was the version comprising a cutter housing 23. The chips were taken directly from the lathe without storage and were processed directly so that the cutting fluid was not allowed to dry or so that the water did not evaporate to a significant extent.

[0086] Example 3

[0087] Chips from a lathe and chips from a milling cutter both comprising cutting fluid were processed with a chip processing machine according to the invention, which machine comprised a cutter housing. In this particular example it was possible to reuse 0.45 liter of cutting fluid per kg of cutting chips from the lathe and about 0.50-0.55 liter of cutting fluid per kg of cutting chips from the milling cutter.

[0088] The invention has mainly been described with reference to a few embodiments. However, as is readily understood by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended claims.

[0089] In the claims, the term "comprises / comprising" does not exclude the presence of other elements or steps. Additionally, although individual features may be included in different claims, these may possibly advantageously be combined, and the inclusion in different claims does not imply that a combination of features is not feasible and / or advantageous. In addition, singular references do not exclude a plurality. The terms "a", "an", "first", "second" etc. do not preclude a plurality. Reference signs in the claims are provided merely as a clarifying example and shall not be construed as limiting the scope of the claims in any way.

Claims

CLAIMS1. A self-feeding chip crusher, comprising a rotatable shaft (12) having a plurality of protrusions (13), a crusher element (17), and a crushing zone (16) between the rotatable shaft (12) and the crusher element (17), wherein chips are configured to be crushed in the crushing zone (16), and wherein more than 120° of the rotatable shaft (12) is exposed to chips added to the chip crusher.

2. The self-feeding chip crusher according to claim 1, wherein the rotatable shaft (12) is elongated and configured to rotate about a rotational axis (A).

3. The self-feeding chip crusher according to claim 1 or 2, wherein the crusher element (17) extends in parallel to and is arranged at a predetermined distance from the rotatable shaft (12).

4. The self-feeding chip crusher according to any one of the preceding claims, wherein the protrusions (13) protrude radially outwards from an outer circumference of the rotatable shaft (12), preferably wherein the protrusions (13) protrude along the length of the rotatable shaft (12).

5. The self-feeding chip crusher according to any one of the preceding claims, wherein the chip crusher (10) further comprises a frame (11), wherein the frame (11) comprises the crusher element (17).

6. The self-feeding chip crusher according to claim 5, wherein the frame (11) further comprises at least one supporting member (18, 19).

7. The self-feeding chip crusher according to claim 6, wherein the at least one supporting member (18, 19) is inclined with respect to the crusher element (17), preferably wherein the at least one supporting member (18, 19) extends in parallel to the rotatable shaft (12).

8. The self-feeding chip crusher according to any one of the preceding claims, wherein the crushing zone (16) represents a gap between the shaft (12) and the crusher element (17).

9. The self-feeding chip crusher according to claim 8, wherein the gap is from 0.3 mm to 8 mm.

10. The self-feeding chip crusher according to any one of the preceding claims, wherein the chip crusher shaft (12) is rotatable both clockwise and counterclockwise.

11. The self-feeding chip crusher according to anyone of the preceding claims, wherein the crusher element (17) is substantially planar, having a crushing edge facing the shaft (12), wherein the crushing edge is substantially smooth.

12. A chip processing machine comprising a self-feeding chip crusher (10) according to any one of claims 1-11.

13. The chip processing machine according to claim 12, further comprising a housing with an opening (2) for receiving chips to be crushed.

14. The chip processing machine according to claim 12 or 13, further comprising at least one stir plate (3, 4).

15. The chip processing machine according to any one of claims 12-14, further comprising a cutter housing (23) having internal spiral grooves, wherein a miller screw (25) is housed in said cutter housing (23) and driven by a drive motor (24), and wherein the cutter plate (26) is fastened to said cutter housing (23).

16. The chip processing machine according to any one of claims 12-15, further comprising a tilt cylinder (28) configured to tilt, or rotate the cutter housing (23) enabling the removal of an item that has become stuck and blocks the miller screw (25).

17. The chip processing machine according to any one of claims 12-16, further comprising monitoring the torque applied by the drive motor (24) by monitoring the drive current to the drive motor (24).

18. The chip processing machine according to any one of claims 12-15, wherein the housing (23) is provided on bearings allowing for rotation and a locking system enabling the cutter housing (23) to be locked in desired positions.

19. The chip processing machine according to any one of claims 12-18, wherein the processing machine comprises a feeding device, which feeds chips to be crushed from a CNC machine.

20. A method of crushing chips wherein the chip processing machine according to any one of claims 12-19 is used and wherein the method comprises the steps of: a) feeding chips to the device, and b) collecting crushed chips form the device.

21. The method according to claim 20, wherein the chips are fed from a CNC machine to the device with a feeding device without intermediate storing and wherein a liquid is collected and fed back to the CNC machine.

Images