Pressure slip casting apparatus for producing sanitary ware

Abstract: A pressure slip casting apparatus for producing a sanitary ware such as a toilet bowl, comprises lifting means (5) secured to a top member (3) of a stationary frame (4); a pair of suspending devices (9) supported by a plate attached to the lifting means (5); an interlocking mechanism (15, 16) operatively connecting the suspending devices (9) to each other; and a device for moving the suspending devices (9) towards and away from each other through the action of the interlocking mechanism. A bottom mould part (17) and a core mould part (18) are attached to the base (1) of the stationary frame and to the lower surface of the plate, respectively. Side mould parts (19) are suspended by the suspending devices (9) so as to be brought and aligned together when the suspending devices (9) are moved towards each other. The core mould part (18) and the side mould parts (19) in assembled state are adapted to be lowered by the lifting means (5) so that the side mould parts (19) and the core mould part (18) are sequentially assembled with the bottom mould part (17) and then clamped therewith. The apparatus further comprises clamping devices (27) provided on side posts (2) and capable of clamping the side mould parts (19) to each other subsequent to the clamping operation performed by the lifting means (5).

Description: The present invention relates to a pressure slip casting apparatus for producing sanitary ware, for example a toilet bowl. In recent years, a pressure slip casting method has been developed which makes use of a porous-resin mould made of a porous resin with continuous pores defining internal draining passages, as a substitute for the conventional plaster mould method. According to this method, since the slip can be deposited on the porous resin mould under pressure, the deposition time can be remarkably shortened as compared with the case where the conventional plaster mould is used. In addition, the long drying time which is required in the case of a plaster mould for the purpose of dehydration can be eliminated. In the pressure slip casting method, however, the mould has to be strong enough to withstand the high moulding pressure. Such high strength or rigidity can be realized by backing up the porous resin with a backup member supported in a steel frame. In such a case, however, the weight of the mould is increased to undesirably hamper the handling of the mould. DE-A-2 100 868 discloses apparatus for use in providing articles produced by a blow moulding method using thermoplastic synthetic resin. The apparatus comprises a frame with a rail at the bottom. The mould halves are fixed to mould clamping plates which are mounted on wheeled supports which run on the rail. The supports are moved towards and away from each other horizontally by individual servo motors. Syncronism of movement with respect to the blowing plane is achieved by a stationary pinion which meshes with two racks mounted one on each support. A locking mechanism is mounted on one side of the frame and comprises tie rods which in the locking position extend through both mould clamping plates. EP-A-0211653 discloses a pressure slip casting apparatus which comprises an upper mould part, a lower mould part and a pair of side mould parts which are connected to respective rams. After moulding, rams connected to the upper and lower mould parts are retracted to move upwardly and downwardly the upper mould part and the lower mould part, respectively thereby separating the moulded article from the upper and lower mould parts. Subsequently, a trolley with a liftable table is introduced into the casting apparatus and the liftable table is lifted to a level at which the table is just going to contact the lower surface of the moulded article. Then, the rams connected to both side mould parts are retracted to move the side mould parts away from each other to release the moulded article, whereby the moulded article is placed on the table. In this known apparatus, it is difficult to synchronize the releasing motions of both side mould parts because these mould parts are connected to and operated by independent rams, thus posing a risk of deformation of the moulded article during releasing. In addition, connecting and fixing of each mould part to the associated ram are not easy to conduct because the mould part is heavy. Thus, the efficiency of the work is impaired and difficulty is encountered also in attaining alignment between both side mould parts. Furthermore, the rams connected to both side mould parts are required to have a large stroke, because these rams must perform both the mould clamping and releasing actions. This inevitably increases the size of the moulding apparatus, despite a demand for a compact construction of the apparatus. It is also to be noted that a complicated trolley with a liftable table has to be used for delivering the moulded article out of the moulding apparatus, resulting in an increase in the cost. DE-A-2 227 234 discloses apparatus for use in the production of ceramic castings using a mould comprising a base, side parts and a cover. The apparatus comprises a stand with a vertically movable slide carrying horizontally movable arms, for engaging the mould side parts, and a device for engaging and lifting the cover away from the mould side parts. Movement of the various pieces of the apparatus is effected by separate piston and cylinder units. The arms are capable of moving the mould side parts vertically upwardly and downwardly to the base, and horizontally towards and away from each other. Each arm has two pairs of clamping cylinders for engaging a respective grip strip provided on the mould side parts. The mould with the cast product is delivered to the apparatus on a wheeled carriage, and the arms of the apparatus engage the mould side parts, lifting them from the base on the carriage and placing them on a conveyor, and then moving them away from each other horizontally to leave the cast product on the conveyor. The present invention provides a pressure slip casting apparatus for producing sanitary ware comprising: a stationary frame including a base, side posts and a top member; a mould having a bottom mould part, a core mould part and a pair of side mould parts each being formed of a porous body with internal passages; lifting means secured to the top member of the stationary frame; and a pair of suspending devices supported by a plate attached to the lifting means; the side mould parts being suspended by the suspending devices so as to be brought and aligned together when the suspending devices are moved towards each other, the core mould part and the side mould parts in the assembled state being adapted to be lowered by the lifting means so that the side mould parts and the core mould part are sequentially assembled with the bottom mould part characterised by an interlocking mechanism for operatively connecting the suspending devices to each other; means for moving the suspending devices towards and away from each other through the action of the interlocking mechanism; the bottom mould part and the core mould part being attached to the base of the stationary frame and to the lower surface of the plate, respectively, the core mould part being assembled with the side mould parts assembled with the bottom mould part, merely by lowering the plate and clamped to the side mould parts under the action of the lifting means; and clamping devices provided on the posts and capable of clamping the side mould parts to each other subsequent to the clamping operation performed by the lifting means. After casting of the slip, the operation of the clamping devices is terminated and the core mould part is raised apart from the side mould parts by the operation of the lifting means. Subsequently, the suspending devices are raised to lift the side mould parts away from the bottom mould parts so that the moulded article is lifted while being retained between the side mould parts. Then, the trolley is moved into the casting apparatus and set underneath the moulded article. Then, the suspending devices are moved away from each other so as to release the side mould parts from the moulded article, whereby the moulded article is placed on the trolley. In the accompanying drawings, Figure 1 is a front elevational view of a pressure slip casting apparatus; Figure 2 is a side elevational view of the pressure casting apparatus with a part of a stationary frame of the apparatus being omitted; Figure 3 is a front elevational view of the pressure casting apparatus in a state in which mould parts have been assembled together; Figure 4 is an enlarged plan view of a pressure casting apparatus as viewed in the direction of line 4-4 in Figure 1; Figure 5 is a front elevational view of the portion of the pressure casting apparatus shown in Figure 4; Figure 6 is a sectional view of a bottom mould part showing a detail of the construction of this mould as an example of the construction of the mould parts used in the described pressure casting apparatus; Figure 7 is a front elevational view of another pressure casting apparatus; and Figure 8 is a schematic illustration of a mould in the assembled state and a compressed air line for blowing compressed air into the mould cavity. Referring to Figure 1 and 2, a pressure slip casting apparatus for forming a sanitary ware, for example a toilet bowl, has a stationary frame 4 including a base 1, side posts 2 and a top member 3. Lifting hydraulic cylinder devices 5 are fixed to the top member 3 of the frame 4 so as to be situated on the vertical central plane of the frame 4. Each of the lifting hydraulic cylinder devices 5 has a piston 7 which is provided with a supporting plate 6 fixed to the lower end thereof. Travelling guide rails 8 are provided on the front and rear ends of the supporting plate 6. Left and right suspending devices 9 are provided on both sides of the hydraulic lifting cylinder devices 5 and have wheels 10 by means of which these suspending devices travel along the travelling guides 8. Each suspension device 9 has a pair of suspension frames 12 arranged at front and rear sides of the device 9 and connected to each other through a connecting member 11. Figures 4 and 5 show a hydraulic cylinder device 13 which is fixed to the upper side of the supporting plate 6 and has a piston 14 which is connected to the connecting member 11 of one of the suspending devices 9. Extension of the piston 14 causes this suspending device 9 to move along the travelling guides 8. There is provided an interlocking mechanism which is adapted to cause movement of the other suspending device 9 in a direction different from that of the movement of the first-mentioned suspending device 9. As shown in Figure 1, the interlocking mechanism includes sprocket wheels 15 rotatably mounted on both ends of the travelling guides 8, and chains 16 having one end secured to one of the suspending devices 9 and the other end secured to the other suspending device, the chains 16 passing around the sprocket wheels 15. Thus, the pair of suspending devices 9 are connected to each other through a pair of chains 16. When the hydraulic cylinder device 13 is operated to retract its piston 14, the suspending device 9 connected to this piston 14 is moved towards the center of the moulding apparatus. Consequently, one of the chains 16 moves around the sprocket wheels 15 clockwise as viewed in Figure 1 so as to cause the other suspending device 9 to move towards the center of the apparatus by the same amount as that of the movement of the first-mentioned suspending device 9. Conversely, when the piston 14 is extended to displace the associated suspending device 9 outward of the apparatus, the other of the chains 16 moves Counterclockwise around the sprocket wheels 15, so that the other suspending device 9 also moves outwardly of the apparatus by the same amount. The casting apparatus has a mould which includes a bottom mould part 17 fixed to the center of the base 1 of the stationary frame 4, a core mould part 18 stationarily fixed to the lower surface of the supporting plate 6, and a pair of side mould parts 19 which are suspended by the respective suspending devices 9 and spaced by a predetermined distance from the core mould part 18. The suspension of each side mould part 19 from the associated suspending device 9 is realized by engagement between projections 20 projecting from the front and rear ends of the side mould part 19 and hooks 21 provided on the lower ends of the suspending frames 12. The construction of the mould parts will be explained with reference to Figure 6 showing the bottom mould part 17, by way of reference. The bottom mould part 17 includes a reinforcing steel frame 22, a continuous-pore type porous body 24 having internal hollow passages 23, and a backup member 25 supported in the reinforcing steel frame 22 so as to support the porous body 24. A sealing resin layer 26 is interposed between the porous body 24 and the backup member 25 so as to seal the porous body 24. Means for clamping the side mould parts 19 includes a pair of hydraulic presses 27 which are provided on the base portion of each post 2 of the stationary frame 4. Obviously, screw-type presses can be substituted for the hydraulic presses. A slip supply pipe 28 connected to a source (not shown) of slip and a slip discharge pipe 29 are connected to a charging opening 30 formed in the bottom mould part 17. These pipes 28 and 29 are respectively provided with a supply valve 31 and a discharge valve 32. A slip stop valve 33 is provided in the slip supply pipe 28 at a position upstream of the supply valve 31. A slip pressurizing device 34 is connected to a portion of the slip supply pipe 28 between the valves 31 and 33. The slip pressurizing device 34 comprises an expandable pressurizing vessel 35 formed from a rubber bellows and a hydraulic cylinder 36 for expanding and contracting the pressurizing vessel 35. It is of course possible to use other suitable slip pressurizing devices. The casting apparatus is provided with a support pedestal 37 adjacent to the base 1 of the stationary frame 4. A pair of rails 38 are laid on the base 1 of the stationary frame 4 and the supporting pedestal 37 along both lateral sides of the bottom mould part 17. A trolley 39 is so constructed as to straddle the bottom mould part 17 and has wheels which travel on the rails 38 so that the trolley 39 is movable between the support pedestal 37 and the base 1. Figure 7 shows another casting apparatus. This apparatus is substantially the same as the previously described one except that a plugging mould part 41 is disposed on the end of the apparatus opposite to the support pedestal 37. The plugging mould part 41 is secured to the piston of a hydraulic cylinder device 43 mounted on a support frame 42, and forms a part of the mould. It is assumed here that the core mould part 18 and the side mould parts 19 have been raised with respect to the bottom mould part 17 and both side mould parts 19 have been moved away from each other. In this state, as the hydraulic cylinder device 13 is operated to retract its piston 14, both suspending devices 9 are moved along the travelling rails 8 towards the center of the apparatus by the operation of the chains 16 so that the side mould parts 19 which are suspended from the suspending devices 9, are brought together at the central vertical plane of the apparatus. Subsequently, the lifting hydraulic cylinder devices 5 are operated to extend the pistons 7 so that the core mould part 18 and the side mould parts 19 are lowered towards the bottom mould part 17. During this downward movement, the side mould parts 19 come to rest on the bottom mould part 17 at positions between the hydraulic presses 27 so as to be assembled together with the bottom mould part 17 and then the core mould part 18 rests on the side mould parts 19 so as to be assembled with these mould parts 19. Then, the hydraulic cylinder devices 5 are operated to clamp the core mould part 18, side mould parts 19 and the bottom mould part 17 in the vertical direction. In the case of the apparatus shown in Figure 7, the plugging mould part 41 is advanced in this state to be fitted to and clamped against the side mould part 19. Thus, the mould is ready for the casting operation. The stop valve 33 and the supply valve 31 of the slip supply pipe 28, as well as the discharge valve 32 of the slip discharge pipe 29, are opened so that a new batch of slip is supplied from the slip source so that the old slurry stagnant in the slip system is replaced with fresh slip. Then, the discharge valve 32 is closed and the slip is charged into the cavity in the mould through the slip charging opening 30 in the bottom mould part 17 so as to fill the mould cavity with the slip. At the same time, slip is allowed to flow into the pressurizing vessel 35 of the slip pressurizing device 34 communicating with the slip supply pipe 28. Then, the slip pressurizing device 34 is actuated to extend its piston so as to apply a predetermined pressure to the slip in the pressurizing vessel 35 for a predetermined time. As a result of the pressurizing of the slip, the water in the slip is forced into the pores of the porous bodies 24 of the mould and discharged outside the mould through the internal passages 23, whereby a moulded article is deposited on the surfaces of the mould cavity presented by the porous bodies 24. The pressure in the internal passages 23 may be actively reduced to promote the movement of the water into the mould parts. After a desired thickness of the slip has been deposited on the surfaces of the mould parts defining the mould cavity, the supply valve 31 is closed and the operation of the hydraulic cylinder devices 5 is stopped. Then, the discharge valve 32 is opened and a valve 45 in an air line is opened so that compressed air is supplied into the mould cavity, whereby surplus slip in the mould is discharged through the slip discharge pipe 29. As shown in Figure 8, the valve 45 is provided in an air line 44 which is connected to a source of compressed air (not shown) and which communicates with the mould cavity. After completion of the discharge of the slip, the discharge valve 32 and the valve 45 are closed and a valve 46 in the air line 44 is opened so that pressurized air is supplied into the mould cavity for a predetermined time to promote the movement of the water in the moulded article 48 into the porous bodies, until the moulded article becomes rigid enough to permit the separation. After a predetermined time has elapsed, the valve 46 is closed and the slip valve 32 is opened to allow the mould cavity to communicate with the atmosphere. A check valve 47 is provided in the air line 44 between the valves 45 and 46 and the mould parts 17, 18 and 19 to prevent slip from flowing back into the valves 45 and 46. A description will now be given of the releasing operation for allowing the moulded article to be taken out of the mould. The clamping force is released by relieving the hydraulic pressure in the lifting hydraulic cylinder devices 5 and the hydraulic presses 27 and also in the hydraulic cylinder 43 for the plugging mould part 41 in the apparatus shown in Figure 7. Then, compressed air is supplied from the exterior through the internal passages 23 into the plugging mould part 41 so that the water in the porous bodies 24 is forced back to the boundary between the moulded article and the surfaces of the mould cavity, thus forming a water film along the boundary to facilitate release of the moulded article 48 from the mould part. Then, the hydraulic cylinder 43 is retracted to separate the plugging mould part 41. Subsequently, the hydraulic presses 27 are completely extracted and compressed air is introduced from the exterior through the internal passages 23 into the core mould part 18 so that the water in the porous body 24 is forced back to the boundary between the moulded article and the mould cavity surface, thereby forming a water film along this boundary to facilitate release of the moulded article from the mould part. The lifting hydraulic cylinder devices 5 are then actuated to lift up the core mould part 18, while raising the suspending devices 9. In this state, however, the side mould parts 19 have not been suspended yet by the suspending devices 9. Namely, the retracting motion of the lifting hydraulic cylinder devices 5 is temporarily stopped at a moment immediately prior to the lifting of the side mould parts 19 by the suspending devices 9, and compressed air is supplied from the exterior through the hollow passages 23 into the bottom mould part 17 so as to force the water in the porous body 24 back to the boundary between the moulded article 48 and the surface of the bottom mould part, thus forming a water film thereby facilitating the separation of the moulded article from the bottom mould part. Then, the retracting operation of the lifting hydraulic cylinder devices 5 is re-commenced to raise the suspending devices 9 so that the side mould parts 19 with the moulded article 48 are suspended by the suspending devices 9 so as to be moved upward apart from the bottom mould part 17 thus separating the moulded article from the bottom mould part 17. After the lifting hydraulic cylinder devices 5 have reached the limit of their upper stroke so completely suspending the side mould parts 19, the trolley 39 carrying a support plate 47 is moved into the moulding apparatus. Then, the lifting hydraulic cylinder devices 5 operate again to lower the side mould parts 19 until the bottom surface of the moulded article 48, still clamped between the side mould parts 19, just contacts the supporting plate 47, for example, to a level at which the bottom surface of the moulded article is about 1 to 2mm above the surface of the supporting plate 47. Then, compressed air is supplied from the exterior through the internal passages 23 into the side mould parts 19 so that the water in the porous bodies 24 is moved to the boundaries between both side mould parts and the moulded article 48 so as to form water films in these boundaries, thus facilitating the separation. Then, as the hydraulic cylinder device 13 is extended, the suspending devices 9 are moved away from each other by the action of the chains 16 and both side mould parts 19 are moved apart to release the moulded article 48 so as to allow the moulded article 48 to rest on the supporting plate 47. Finally, the trolley 39 is driven out of the moulding apparatus onto the support pedestal 37, thus completing the take-up of the moulded article 48. Aligning and releasing of the side mould parts is effected by a single hydraulic cylinder device mounted on a support plate carried by lifting hydraulic cylinder means, while the clamping of the side mould parts is conducted by stationary clamping devices. Thus, the stroke of the clamping devices can be reduced to enable the apparatus to have a compact design. Furthermore, since the side mould parts are suspended from a supporting plate through suspending devices which are movable laterally towards and away from each other, replacement of the mould parts and adjustment of the mould parts for alignment are facilitated. Furthermore, since the assembling and separation of the core mould part and the bottom mould part can be effected only by the lifting hydraulic cylinder devices, the mould assembling and releasing operations are simplified to shorten the time required for the releasing of the mould. The bottom mould part is fixed to the base of the stationary frame while the oore mould part and the side mould parts in assembled state are moved up and down between the clamping devices by the operation of the lifting hydraulic cylinder devices, and the trolley is moved into and out of the moulding apparatus while the core mould part and the side mould parts are in the raised positions. With this arrangement, it is possible to simplify the construction of the whole apparatus, thus contributing to the reduction of the size of the whole apparatus. Furthermore, since both side mould parts are brought into alignment with each other and moved apart from each other by the operation of a single hydraulic cylinder device through the action of the interlocking mechanism, both side mould parts are moved strictly at the same speed in synchronization with each other, whereby the assembly of the side mould parts and separation of these mould parts from the moulded article can be conducted smoothly.

Claims: A pressure slip casting apparatus for producing sanitary ware comprising: a stationary frame (4) including a base (1), side posts (2) and a top member (3); a mould having a bottom mould part (17), a core mould part (18) and a pair of side mould parts (19), each being formed of a porous body (24) with internal passages (23); lifting means (5) secured to the top member (3) of the stationary frame (4); and a pair of suspending devices (9) supported by a plate (6) attached to the lifting means (5); the side mould parts (19) being suspended by the suspending devices (9) so as to be brought and aligned together when the suspending devices (9) are moved towards each other, the core mould part (18) and the side mould parts (19) in the assembled state being adapted to be lowered by the lifting means (5) so that the side mould parts (19) and the core mould part (18) are sequentially assembled with the bottom mould part (17); characterised by an interlocking mechanism (15,16) for operatively connecting the suspending devices (9) to each other; means (13,14) for moving the suspending devices (9) towards and away from each other through the action of the interlocking mechanism (15,16); the bottom mould part (17) and the core mould part (18) being attached to the base (1) of the stationary frame and to the lower surface of the plate (6), respectively, the core mould part (18) being assembled with the side mould parts (19) assembled with the bottom mould part (17), merely by lowering the plate (6) and clamped to the side mould parts (19) under the action of the lifting means (5); and clamping devices (27) provided on the posts (2) and capable of clamping the side mould parts (19) to each other subsequent to the clamping operation performed by the lifting means (5). A pressure slip casting apparatus according to claim 1, further comprising a plugging mould part (41) and a device (43) for aligning the plugging mould part (41) and clamping it to the side mould parts (19) and the core mould part (18) after the side mould parts (19) and the core mould part (18) have been clamped to the bottom mould part (17).

Inventors: HISAEDA MASANOBU, OGATA MASAHIRO, SAITOU SATORU, HISAEDA, MASANOBU, OGATA, MASAHIRO, SAITOU, SATORU
Applicants: TOTO LTD, TOTO LTD.
Application year: 1990
Main classification: B28B1
IPC codes: G06F17, B28B1, B28B13