[Document Type] Specification [Title of the Invention] Chip Discharge Conveyor System Equipped With a Filtration Device [Detailed Description of the Invention] [0001] [Technical Field of the Invention] During a metal working or a resin finishing process such as cutting or grinding performed by a machine tool, a machine tool discharges coolant and chips of assorted sizes, including cutting or grinding chips of iron-, aluminum-, or copper-based metal or resin that are discharged from the machine tool. The present invention relates to a chip discharge conveyor system equipped with a filtration device, wherein dirty coolant containing chips of assorted sizes is charged into a treatment tank comprising a hinged belt type conveyor provided in the treatment tank such that the hinged belt conveyor runs and circulates; and whereby chips are separated from coolant and only the chips are removed and transported by the conveyor to a chip discharge portion to discharge them out from the treatment tank, and wherein coolant filtered by a filtration drum provided inside the conveyor is drained in the lateral outward direction of the treatment tank.

[03302] [Prior Art] When a machine tool cuts or grinds metal or resin material, a coolant such as cutting oil or lubricant dissolved in water is used to cool the cutting or grinding tool, or a workpiece. Conventionally, a chip discharge conveyor system wherein a hinged belt conveyor removes only chips out from dirty coolant discharged from a machine tool and discharges such chips out from a treatment tank while clean coolant filtered by a filtration drum is discharged in the lateral direction of the treatment is publicly known (for example, Japanese Unexamined Patent Application, First Publication, 2000-202215, Patent Gazette).

[0003] Figures 9 and 10 show a part of a conventional chip discharge conveyor system.

A conventional chip discharge conveyor system 11, in general, comprises a dirty coolant treatment tank 12, a hinged belt type conveyor 14 provided in the treatment tank 12, and a filter drum 15 provided inside the conveyor 14.

[0004] The conveyor 14 is equipped with an endless hinged belt 13 and a side chain 13a, which circulate and make a turn at a conveyor tail portion A and a chip discharge portion (not shown in the figures) in the treatment tank 12. In this case, the side chain 13a is wound around a driven tail disk 14c for slidable contact at the conveyor tail portion A, and is wound around a driving sprocket (not shown in the figures) at the chip discharge portion. It should also be noted that 13b in Figure 10 is an outer cleat attached to an outer circumferential surface of the hinged belt 13.

[0005] The filtration drum 15 is provided between a discharge belt 14a which is a portion of the hinged belt, the hinged belt serving to transport and discharge chips and running at the top, and a return belt 14b, the return belt being a portion of the hinged belt and functioning as a return portion of the hinged belt while running at the bottom.

Additionally, a bottom plate of the treatment tank 12 is formed by a horizontal bottom plate 12 provided in the longitudinal direction aligning in a row with a curved cover 12a provided on the conveyor tail portion A and a hollow-ground bottom plate 12c having a circular shape to allow the filtration drum 15 to be provided underneath. For the hollow-ground bottom plate 12c, an inclined wall surface plate 12d is provided, extending to the chip discharge portion (not shown in the figures) located diagonally upward.

[0006]<BR> In the chip discharge conveyor system 11, when dirty coolant containing chips<BR> of assorted sizes is charged into the treatment tank 12 from above, large chips kl (metal or resin chips such as long chips, curled chips, or solid dumpling-like chips where such long or curled chips accrete) are caught by the discharge belt 14a of the conveyor 14, and then transported to and discharged at the chip discharge portion located above the treatment tank 12, while the filtration drum 15 filters dirty coolant to make filtered clean coolant which outflows from a coolant discharge opening 15a down to a coolant tank E located downward or laterally to the treatment tank 12 and is returned back to the machine tool for recycling.

[0007] In this case, chips which are not caught by the discharge belt 14a, but have precipitated onto the bottom plate are scraped out and transported to the conveyor tail portion A by the outer cleats 13b of the return belt 14b. When the return belt 14b makes an upward turn at an upturn belt section, the chips are scooped by the outer cleats 13b and are transported by the discharge belt 14a to discharge.

[0008] [Problems to be Solved by the Invention In a conventional chip discharge conveyor system as mentioned above, when small chips which pass through a clearance between two adjacent hinged plates are caught on an inner circumferential surface of the return belt which runs at the bottom, the chips are transported to the conveyor tail portion A.

However, when the return belt makes an upward turn, the chips continuously drop onto the return belt inside the upturn belt section and remain in a cavity inside the upturn belt section, where the chips gradually aggregate to become a sausage-like mass, MI. Then, the mass of chips grown inside the upturn belt section vertically pushes the discharge belt and the return belt, which consequently stops the conveyor in due course.

Whenever the conveyor shuts down due to a mass of chips like this, the conveyor must be detached from the inside of the machine tool for removal of the mass of chips for cleaning of the inside.

[0009] The treatment tank bottom plate where the filtration drum is provided is formed as a circular-shaped hollow-ground plate to allow the filter drum to be located underneath. The uppermost portion of the circular arc of the hollow-ground plate is directly connected to the horizontal bottom plate at an articulated section. As shown in Figure 9, the return belt 14b runs along the bottom plate, therefore, chips dropped from thb filtration drum at the articulated section 12e tend to grow into a mass of chips M2 on the return belt 14b at the articulated section 12e. Once the mass is formed, it further grows, which consequently presses and damages a filter surface of the filtration drum 15.

[0010] It is initially desired for a chip discharge conveyor system to keep dirty coolant level lower than the discharge belt. However, a machine tool uses more than one coolant supply pipe depending on a given purpose. Normally, an appropriate number of pumps are accordingly operated or stopped. However, when a pump starts up, a massive amount of dirty coolant is charged at one time or a massive amount of chips is supplied, which consequently raises the coolant level in the vicinity of an inlet and causes overflow from the treatment tank because flow of dirty coolant to be blocked.

[0011] It should also be noted that the chip discharge conveyor system described in the aforementioned Japanese Unexamined Patent Application, First Publication, 2000-202215, Patent Gazette, a spray nozzle is provided inside the conveyor and sprays filtered clean coolant to wash off chips underneath the return belt. However, when chips are small in size or specific gravity, the chips shoot out and scatter in dirty coolant, enhancing chip density, and promotes clogging of the filter of the filtration drum.

[0012] It is accordingly a general object of the present invention to overcome the foregoing drawbacks of the prior art.

A more specific object of the invention is to provide a chip discharge conveyor system which can prevent chips from remaining inside the upturn belt section at the conveyor tail portion to develop and cause a mass of chips to aggregate when dirty coolant containing chips of assorted sizes is treated, can prevent a filter of the filtration drum from being damaged due to the aggregated mass of chips by hindering chips from remaining on the return belt below the filtration drum to grow the mass of chips, can restrain chips which shoot out or scatter in dirty coolant from adhering to the filtration drum, can retard clogging of the filter of the filtration drum, and can restrain coolant level from raising to prevent overflow even when a massive amount of dirty coolant is supplied at one time, while collecting chips of assorted sizes as well as recovering clean coolant at the same time.

[0013] [Means for Solving the Problem] To achieve the foregoing object, the invention according to claim 1 is a chip discharge conveyor system equipped with a filtration device comprising a treatment tank wherein a hinged belt type conveyor having outer cleats is provided such that the hinged belt conveyor runs and circulates while making an upward turn at a conveyor tail portion, and also provided with a filtration drum disposed within the conveyor, whereby dirty coolant containing chips of assorted sizes are charged into the treatment tank and only the chips of assorted sizes are removed and transported to a chip discharge portion to be discharged outside of the treatment tank, while filtered coolant which is filtered by a filtration drum is discharged to the exterior of the treatment tank, wherein a cylindrical member is provided inside the conveyor tail portion where a return belt of the conveyor makes an upward turn, in the width direction thereof, and a partition plate is provided below a discharge belt of the conveyor in confronted relation to the discharge belt along the length thereof; and a bottom plate of the treatment tank comprises a horizontal bottom plate extending from the conveyor tail portion, a curved bottom plate formed into an approximately circular shape such that the filtration drum will be disposed below the horizontal bottom plate, and an inclined plate having an approximately flat surface and provided between the horizontal bottom plate and the curved bottom. plate gradually inclines upward from the lowermost part of the curved bottom plate toward the horizontal bottom plate; and the filtration drum is provided in a confronted relation to the curved bottom plate via the return belt, such that the return belt runs along the curved bottom plate, the inclined bottom plate, and the horizontal bottom plate of the treatment tank.

The invention according to claim 2 is a chip discharge conveyor system comprising a filtration device according to claim 1, wherein the vicinity of an inlet into which dirty coolant is to be charged is provided with a clearance formed between a side wall of a treatment tank and a corresponding longitudinal edge of a conveyor, whereby dirty coolant outflows by gravity.

The invention according to claim 3 is a chip discharge conveyor system provided with a filtration device according to Claim 1 or Claim 2; comprising inner cleats attached to the inner circumferential surface of the hinged belt type conveyor.

[0014] In the invention mentioned above, for the hinged belt conveyor, the term "discharge belt"is used to refer to the hinged belt which runs at the top, while the term "return belt"is used to refer to the hinged belt which runs at the bottom. It should also be noted that the term"longitudinal direction"is used herein to refer to the direction parallel to the direction that an endless hinged belt runs, while the term"width ditection"is used herein to refer to the direction perpendicular to the direction that the hinged belt runs. For chips of assorted sizes, the term"large chips"is used to refer to those chips whose sizes are big enough not pass through a clearance of a hinged belt but are caught by the discharge belt, while the term"small chips"is used to refer to those chips whose sizes are small enough to precipitate, passing through a clearance between two adjacent hinged plates of the hinged belt, or a clearance of the side chain.

[0015] [Operation of the Invention] In the previously described chip discharge conveyor system, when dirty coolant containing chips of assorted sizes are charged into the treatment tank, large chips are caught on the discharge belt to be transported and discharged. Small chips which are not caught by the discharge belt are accumulated onto the partition plate, are caught on the return belt (on an inner circumferential surface of the hinged belt type conveyor), or precipitate and accumulate onto the bottom plate of the treatment tank.

The small chips which accumulate onto the bottom plate of the treatment tank are scraped by the outer cleats of the return belt which runs at the bottom, and scooped up by the return belt when it makes an upward turn at the conveyor tail portion. The scooped chips are then transported and discharged along with large chips by the discharge belt which runs at the top.

It should also be noted that the small chips caught on the return belt stay on the return belt to be transported to the conveyor tail portion, and, when the conveyor makes an upward turn at the conveyor tail portion, the small chips are transported in a partial circumferential path along the length of the cylindrical member provided at the upturn belt section and then transferred onto the partition plate via a projection of a hinge sleeve which connects two adjacent hinged plates or via the inner cleat. Consequently, such small chips as well as chips caught on the partition plate are transported on and along the partition plate, using the discharge belt and the partition plate, to discharge the chips at the chip discharge portion. In this case, chips precipitated onto the return belt below the filtration drum can be transferred to the conveyor tail portion without a mass of chips growing because the return belt runs along the inclined bottom plate which gradually inclines upward.

Meanwhile, coolant filtered by the filtration drum flows to the outside from one side or both sides of the treatment tank.

[0016] [Embodiments of the Invention] An embodiment of the invention is described in reference to Figures 1 to 8.

As shown in Figure 1, a chip discharge conveyor system 1 comprises a treatment tank 2 for dirty coolant K, a hinged belt type conveyor 4 comprising an endless hinged belt 3 provided inside the treatment tank 2, a cylindrical member 5 provided inside an upturn belt section where a return belt 4b makes an upward turn at a conveyor tail portion A, a longitudinally extending partition plate 6 provided below a discharge belt 4a in a confronted relation to the discharge belt 4a, and a filtration drum 8 provided between the partition plate 6 and the return belt 4b.

[0017] In the chip discharge conveyor system 1, when dirty coolant K containing chips of assorted sizes is charged into the treatment tank 2, only chips of assorted sizes kl and k2 are transported to a chip discharge portion B and discharged to a chip collection box D, while clean coolant C filtered by the filtration drum 8 outflows to a clean coolant storage tank E located below or by the side of the treatment tank 2. F in each Figure denotes the direction for the conveyor to advance.

[0018] As shown in Figures 1 and 2, a bottom plate of the treatment tank 2 is formed by articulating a horizontal plate 2b extending from a cover 2a of conveyor tail portion A, an inclined bottom plate 2c, and a curved bottom plate 2d which is approximately circular in shape to allow the filtration drum 8 to be located below the bottom plate 2b.

The inclined bottom plate 2c is an approximately flat surface plate which is gradually inclined upward from the lowermost part 2d'of the curved plate 2d toward the horizontal bottom plate 2b, or a plate which is slightly curved toward the return belt 4b side. It is preferable to keep angle of incline 0 against the horizontal surface of the inclined bottom plate 2c at 30 degree or less. 2e in Figures 1 and 2 denotes an inclined wall surface plate provided between the curved bottom plate 2d and the chip discharge portion B.

[0019] The conveyor 4 comprises the hinged belt 3 whose side chain 3b is wound around a tail disk 4c at the conveyor tail portion A, and around a driving sprocket 4d at the chip discharge portion B, so that the conveyor 4 can circulate.

[0020] As shown in Figure 4 and 5, the hinged belt 3 is composed of a number of hinged plates 3a connected with one another by belt pins 3c inserted through hinge sleeves 3a'. The hinged plates 3a are longitudinally arranged between a pair of side chains 3b each consisting of a roller chain. The hinge sleeves 3a'each form together with one belt pin 3c a joint portion of the hinged plate 3a, the hinge sleeve projecting outward from both the front and rear surface of the hinged belt 3. The side chain 3b comprises a link plate 3d and a roller 3e, and the roller 3e is rotatably attached to the belt pin 3c.

[0021] Each of the hinged plates 3a has a pair of side wings 3f attached to opposite ends thereof in the width direction of the hinged belt 3. As shown in Figure 3, each of the side wings 3f is composed of a wing plate 3fl and a mounting plate 3f2 and is attached to the hinged plate 3a via the mounting plate 3f2. Adjacent wing plates 3fl of one side wing 3f overlap with each other in the width direction of the hinged belt 3 so that there is no space formed between adjacent two wing plates 3fl even when the hinged belt 3 makes an upward turn at the conveyor tail portion A.

[0022] An outer circumferential surface of the hinged belt 3 has outer cleats 3g which are mounted at intervals of several pieces of hinged plates 3a, while an inner circumferential surface of the hinged belt 3 has inner cleats 3h which are relatively low and mounted, keeping a certain interval (see Figure 3).

[0023] As shown in Figures 3 and 6, the conveyor 4 circulates while making an upward turn at the conveyor tail portion A, wherein a pair of tail disks 4c are provided to wind the side chain 3b of the hinged belt 3, and a cylindrical member 5 composed of a pipe or a tube is provided between the pair of tail disks 4c, namely, along the width direction.

[0024] The cylindrical member 5 functions, as an assistant member, to guide and support the small chips k2 caught on the return belt 4b by means of inner cleats 3h to carry small chips k2 in a partial circumferential path along the length of the cylindrical member 5 to the partition plate 6 when the hinged belt 3 makes an upward turn.

Therefore, the cylindrical member 5 doesn't need to rotate. In Figure 6,2f denotes a return belt track which guides and supports the return belt, while 2g denotes a hold-down track which guides, supports, and holds down the discharge belt.

[0025] The flat surface plate partition plate 6 whose width is approximately the same as that of the hinged belt 3 is provided below the discharge belt 4a of the circulating conveyor 4 in confronted relation to the discharge belt 4a extending over the longitudinal direction (see Figures 1,2, and 7). The partition plate 6 has opposite longitudinal edge portions serving as guide rails for the discharge belt 4a (see Figure 7).

A chip discharge mechanism 7 is provided to the partition plate 5 at the chip discharge portion B to discharge the small chips k2 carried onto the partition plate 6.

[0026] The chip discharge mechanism has a structure wherein chips drop from an opening 7a at the dead end of the partition plate 6 onto a trough-like chute and then slide in an inclined chute 7b which is provided at an outer surface of the side of the treatment tank 2 and is inclined diagonally downward to discharge the chips into a chip collection box D, as shown in Figure 1, or a structure which drops chips into a trough 7'b below an opening 7'a and discharge them by a screw conveyor 7'c as shown in Figure 8. The screw conveyor 7'c is driven by sprocket 7'd which engages with the side chain 3b.

[0027] As shown in Figures 1 and 2, the filtration drum 8 composing a filtration device is provided between the partition plate 6 and the return belt 4b running at the bottom, to be accommodated inside the curved bottom plate 2d wherein the return belt 4b runs diagonally into the treatment tank from above and changes its direction to run in the horizontal direction. Additionally, the filtration drum 8 is driven when sprocket 8 provided at the end of the filtration drum 8 engages with the side chain 3b which runs at the bottom.

[0028] In Figures 1 and 2,8b denotes a coolant discharge opening for clean coolant, and 8c denotes a spray nozzle to wash a filter of the filtration drum 8, which washes off chips attached to the drum filter surface to drop the chips down onto the return belt by clean coolant sprayed through the spray nozzle 8c and transport the chips to the conveyor tail portion A.

[0029] As shown in Figure 7, a clearance G for dirty coolant to outflow by gravity is provided between a side wall 2h of the treatment tank 2 in the vicinity of an inlet for dirty coolant K to be charged and an end 4e of the discharge belt 4a in the width direction thereof, while a deflector plate 2j is provided on the side wall 2h to guide dirty coolant flow onto the return belt 4b. When abnormal conditions arise where a massive amount of dirty coolant K is temporarily charged into the treatment tank 2, the clearance G for dirty coolant to outflow by gravity leads dirty coolant K which flows over a guide member 2i of the side wing 3f to a lower region of the treatment tank, and thus retards coolant level from rising and prevents overflow. It should also be noted that the inlet for dirty coolant may be mounted at any space above either the horizontal bottom plate 2b or the inclined bottom plate 2c.

[0030] In the chip discharge conveyor system as described above, when dirty coolant K containing chips of assorted sizes is charged into the treatment tank 2 from above, large chips kl are caught on the discharge belt 4a, and transported to and discharged at the chip discharge portion B located diagonally above the treatment tank 2 for chip collection by the chip collection box D. The chip discharge belt 4a runs diagonally upward, receiving chips by the action of outer cleats while draining coolant off to discharge only chips.

[0031] Small chips k2 which are not caught on the discharge belt 4a accumulate onto the partition plate 6, or are caught on the return belt 4b (the inner circumferential surface of the hinged belt), or precipitate and accumulate onto the bottom plates of the treatment tank 2, such as the horizontal bottom plate 2b, the inclined bottom plate 2c, and the curved bottom plate 2d. Small chips k2 accumulated onto the bottom plates of 2b, 2c, and 2d are scraped out by the outer cleat 3g of the return belt 4b running along the bottom plates and transported to the conveyor tail portion A, wherein such chips are scooped up by the return belt 4b when the return belt 4b makes an upward turn, and then, the scooped chips are transported and discharged along with large chips by the discharge belt 4a which runs at the top. At this time, some of small chips k2 drop down from the discharge belt 4a and precipitate, and are then scraped again to be transported.

[0032] It should also be noted that the small chips k2 caught on the return belt 4b stay on the return belt 4b to be transported to the conveyor tail portion A, and, when the conveyor 4 makes an upward turn at the conveyor tail portion A, the small chips are transported in a partial circumferential path along the length of the cylindrical member 5 provided at the upturn belt portion and then transferred onto the partition plate 6 via the inner cleat 3h. Consequently, such small chips as well as the chips k2 caught on the partition plate 6 are transported on and along the partition plate 6 to the discharge portion B, using the inner cleat 3h of the discharge belt 4a and the partition plate 6, ensuring that the chip discharge mechanism 7 discharges chips which are collected by the chip collection box.

[0033] In this case, chips k2 precipitated onto the return belt 4b below the filtration drum 8 can be smoothly transferred to the conveyor tail portion A without a mass of chips growing because the return belt 4b runs along the inclined bottom plate 2c which is extends to the curved bottom plate 2d and gradually inclines upward. Consequently, the drum filter can be protected against damage caused by a mass of chips.

[0034] Additionally, when dirty coolant K is charged, the discharge belt and the partition plate 6 alleviate the force of flow created by charged coolant, restraining chips from shooting or scattering between the partition plate 6 and the return belt 4b, which consequently retards rise in chip concentration of dirty coolant flowing into the filtration drum, thereby the frequency of the filter of the filtration drum becoming clogged is reduced.

[0035] Meanwhile, dirty coolant K is filtered by the filtration drum 8, and filtered clean coolant C outflows from a side of the treatment tank 2 into an external clean coolant tank E for collection. In this case, when the filtration drum 8 has the coolant discharge opening 8b provided on both sides thereof, clean coolant can efficiently outflow.

[0036] One embodiment has been explained, but it is not always necessary to provide the inner cleat 3h on the hinged belt 3. Instead of providing the inner cleat 3h, a projection of the hinge sleeve 3a'which connects hinged plates 3a can be utilized as a substitute of the inner cleat 3h. In this case, when the hinged belt 3 makes an upward turn at the conveyor tail portion, chips are transferred via the projection of the hinge sleeve 3a'in a partial circumferential path along the length of the cylindrical member 5 provided inside the upturn belt section and transferred onto the partition plate 6 to be transported on and along the partition plate 6. It should also be noted that the hinged plates may comprise a plane plate with no holes as in the explained embodiment, a plate having a number of small holes or perforations, a dimpled plate having a number of small hollows or dimples in one surface, or any combination of these.

[0037] [Effects of the Invention] As described above, since the hinged belt type conveyor according to the invention has an outer cleat provided on an outer circumferential surface of the hinged belt conveyor, small chips precipitated and accumulated onto bottom plates are scraped off by the outer cleat on a return belt, and scooped up by the return belt when the return belt makes an upward turn at a conveyor tail, and then, the scooped chips can be transported by a discharge belt running at the top to discharge the chips at a chip discharge portion.

[0038] Since a partition plate is provided below the discharge belt of the conveyor in confronted relation to the discharge belt along the length thereof while a cylindrical member is provided inside the conveyor tail portion where the return belt of the conveyor makes an upward turn, in the width direction thereof, small chips caught on the return belt can be transported to the conveyor tail portion, wherein the return belt makes an upward turn, carrying the chips via a projection of a hinge sleeve which connects hinged plates of the hinged belt or via an inner cleat in a partial circumferential path along the length of the cylindrical member provided between the hinged belt and the cylindrical member, whereby chips are transferred onto the partition plate along the cylindrical member. As a result, development of a mass of chips inside an upturn belt section can be prevented, which consequently prevents the conveyor from shutting down due to an aggregated mass of chips, and frequency of maintenance is also decreased thereby.

[0039] It should also be noted that small chips transferred onto the partition plate as described above can be transported together with chips accumulated onto the partition plate on and along the partition plate via the projection of the hinge sleeve which connects hinged plates of the hinged belt or via the inner cleats to the chip discharge portion where chips are discharged.

[0040] Since a filtration drum is provided between the partition plate and the return belt running at the bottom, force created by the flow of charged dirty coolant is alleviated by the discharge belt and the partition plate, which restrains chips from shooting out due to the force created by dirty coolant flowing in the vicinity of the filtration drum, hampers chip concentration from rising due to diffused chips, and consequently prevents the filter of the filtration drum from clogging.

[0041] For a bottom plate of the treatment tank, an approximately flat surface inclined plate which gradually inclines upward from the lowermost part of a curved bottom plate to accommodate the filtration drum is provided toward a horizontal plate extended from the conveyor tail portion, wherein the return belt runs along the inclined bottom plate from the bottom of the filtration drum. Therefore, chips dropped onto the return belt below the filtration drum can be transported onto the return belt to the conveyor tail portion without the chips being retained. Consequently, development of a mass of chips below the filtration drum can be prevented, which consequently protects the drum filter against damage due to an aggregated mass of chips.

[0042] As described above, according to the invention, small and large chips removed from dirty coolant containing chips of assorted sizes as well as filtered clean coolant can be collected at the same time, therefore, one single chip discharge conveyor system can efficiently handle dirty coolant containing chips of assorted sizes.

[Brief Descriptions of the Drawings [Figure 1] Side view of a chip discharge conveyor system according to one embodiment of the present invention [Figure 2] Enlarged side view of the vicinity of a filtration drum of the discharge conveyor system of figure 1 [Figure 3] Enlarged side view of a conveyor tail portion from above [Figure 4] Fragmentary plan view of a hinged belt of the chip discharge conveyor system of figure 1 [Figure 5] Perspective view of a side wing of the discharge conveyor system of figure 1 [Figure 6] Cross-sectional view taken along line X-X'of Figure 4 [Figure 7] Cross-sectional view taken along line Y-Y'of Figure 4 [Figure 8] Plan view of the vicinity of a chip discharge mechanism of the discharge conveyor system of figure 1 [Figure 9] Fragmentary side view of a conventional chip discharge conveyor system [Figure 10] Cross-sectional view taken along line X-X'of Figure 9 [Brief Description of the Reference Symbols] 1 chip discharge conveyor system 2 treatment tank 2b horizontal bottom plate 2c inclined bottom plate 2d curved bottom plate 2d'lowermost part of the curved bottom plate 2e inclined wall surface plate 2h side wall 2i guide member 2j deflector plate 3 hinged belt 3a hinged plate 3a'hinge sleeve 3b side chain 3f side wing 3g outer cleat 3h inner cleat 4 conveyor 4a top discharge belt 4b bottom return belt 4c tail disk 4d driving sprocket 5 cylindrical member 6 partition plate 7 chip discharge mechanism 8 filtration drum 8a sprocket 8b coolant discharge opening K dirty coolant kl, k2 chips of assorted sizes A conveyor tail portion B chip discharge portion E coolant storage tank G clearance for coolant to outflow by gravity