EP1074361B1

EP1074361B1 - Device for loading material into the die cavity of a mould, in particular for pressing ceramic tiles

Info

Publication number: EP1074361B1
Application number: EP00202615A
Authority: EP
Inventors: Ermes c/o L.B.-Officine Meccaniche-S.P.A. Bigi
Original assignee: L B Officine Meccaniche SpA
Current assignee: L B Officine Meccaniche SpA
Priority date: 1999-08-02
Filing date: 2000-07-20
Publication date: 2006-08-23
Anticipated expiration: 2020-07-20
Also published as: DE60030217D1; EP1074361A2; EP1074361A3; ITRE990082A0; ITRE990082A1; IT1310965B1

Description

This invention relates to a device for loading material into the die cavity of a mould, in particular for pressing ceramic tiles.
For this purpose, devices have been known for some time comprising a carriage having a loading compartment the lower end of which is open, and, positioned adjacent to and coplanar with the upper surface of the die, a travel surface along which the carriage loading compartment sealedly slides and which closes the lower end of the compartment. The carriage is driven with reciprocating movement in a horizontal longitudinal direction between a retracted position in which the loading compartment is fed with the tile material, and an advanced position in which it lies above the die cavity, into which it releases the material through its lower end and then scrapes it with a suitable scraper means, to make it coplanar with the upper surface of the die.
When in its retracted position, the carriage lies on the travel surface, the lower end of its loading compartment being closed by this surface. When the carriage then slides onto the die, said lower end is closed by the die upper surface.
The amount of material loaded into the carriage at each cycle is necessarily at least slightly greater than the amount which later during the same cycle is released into the die cavity, to ensure that the cavity is completely filled after scraping.
Consequently, after each cycle some of the material remains associated with the scraper means in the carriage loading compartment, causing problems.
One of these problems is that at least a part of this residual material can remain within the carriage for several cycles and can easily be compressed or rolled between the carriage and the surfaces on which this slides, with the result that certain physical characteristics of the material can undergo alteration, in particular its density in the case of atomized material, causing defects within the bulk and on the surface of the final tile.
A further problem arises particularly if the die is loaded with a number of different materials in a determined mutual relationship, for example a first material forming a lower layer and a second material forming the upper layer. In such cases, the residual material of one cycle can contaminate the material of the next cycle. For example, the residual material usually consists of the material of the upper layer (scraped away by the scraper means) and in the next cycle finishes up mixed with the material of the lower layer, causing possible finished product defects.
Moreover, if this material is of the type which softens at relatively low temperature, when it is heated it can soften and, as it collects in the lowest part of the tile, it can soil those machine parts with which it comes into contact, so damaging them.
An apparatus of the above mentioned type is disclosed in the document NL 6807426, having at least one carriage provided with a loading compartment suitable to transfer the powder material from below means for feeding the material into the loading compartment to a position above the mould cavity in which the powder falls within the mould cavity.
The carriage travels onto a surface coplanar with the mould cavity upper surface. At least two carriages can be provided for, to feed two different powder in the same cavity before pressing.
An object of the invention is to provide a device able to overcome said problems in an effective and simple manner.
This and further objects are attained by the device of the invention as characterised in the claims.
The invention is based on the idea of making all or a part of said travel surface movable, in such a manner as to define at least one transverse overflow for the fall of the material, involving the entire width of the carriage loading compartment and of the scraper means. This overflow is automatically opened by suitable means during the carriage return travel, and is closed during its outward travel.
Consequently, whereas the lower end of the carriage loading compartment is closed by the travel surface and by the upper surface of the die during the outward travel, during the return travel the residual material is made to run over the open overflow so as to completely discharge through it with the result that the carriage is completely emptied, including the material scraped away by the scraper means, before receiving a new load of material.
In a preferred (but not exclusive) embodiment, the entire travel surface is movable in a horizontal longitudinal direction between an advanced position in which it is adjacent to the die and a retracted position in which it is distant therefrom so as to leave open at least one transverse region between the front edge of the travel surface and the corresponding edge of the die, to define said overflow for the fall of the material. Means are also provided to move the travel surface synchronously with the carriage movement such that the carriage return travel takes place while the travel surface is in its retracted position, whereas the carriage outward travel takes place while the travel surface is in its position adjacent to the die.
The invention is described in detail hereinafter with the aid of the accompanying figures, which show one embodiment thereof by way of non-limiting example.
Figure 1 is a simplified partly sectional vertical side elevation of the device of the invention applied to a press for pressing ceramic tiles.
Figures 1A and 1B show the same enlarged detail of Figure 1 in two different configurations.
Figure 2 is a section on the horizontal plane II-II of Figure 1.
Figure 3 is a section on the vertical plane III-III of Figure 2.
Figure 4 is a side view in the direction of the arrow IV of Figure 2.
Figure 5 is a section on the vertical plane V-V of Figure 2.
Figure 6 is a section on the vertical plane VI-VI of Figure 2.
The tile pressing mould comprises a die 9 having a flat upper surface 91 in which a cavity 8 is provided, and an upper punch 7 which interacts with the cavity 8 such as to compress a quantity of material within the cavity in order to produce a pressed tile.
The mould can be of multiple type, ie comprise several cavities 8 and a corresponding number of punches 7.
The device of the invention is associated with the mould, in order to load the material to be pressed into the cavity 8.
The device comprises a horizontally extending loading compartment 11 bounded by a lateral frame 12 and having in plan view a shape and dimensions identical to those of the cavity 8 (or group of cavities 8 in the case of a multiple mould), and having its lower and upper ends completely open. The carriage 10 comprises two longitudinal elements 13, which support both the frame 12 and other usual members positioned to the front of the frame, such as a rotary brush 14 for cleaning the upper surface 91, a transverse pusher element 15 for pushing away from the die at each cycle that tile pressed in the previous cycle, and a scraper means 17 positioned in front of the frame 12 to scrape the material discharged into the cavity 8 in order to make it coplanar with the surface 91.
To the side of the die 9 there is a horizontal travel surface 20 (defined by the upper surface of a horizontal table 22) positioned adjacent to and coplanar with the upper surface 91 of the die 9. Along this surface 20 and and along the surface 91 there sealedly slide the frame 12 and scraper means 17, which are driven with reciprocating movement in the longitudinal direction between a retracted position in which the loading compartment 11 is fed with the tile material, and an advanced position in which it releases the material into the die cavity 8 through the open lower end of the compartment 11. The drive means for the compartment 11 (of known type, not shown in the figures) are positioned to the rear of the travel surface 20 and drive the compartment 11 via the longitudinal elements 13.
The travel surface 20 is of such a size as to contain in plan view the entire compartment 11 when this is pulled rearwards into its retracted position.
Above the travel surface 20 there are positioned the means 16 (of known type and shown only schematically in the figures) for feeding the material into the loading compartment 11 when this is in its retracted position.
According to the invention, the travel surface 20 is movable in a horizontal longitudinal direction between an advanced position in which it is adjacent to the die 9 and forms a single plane with the upper surface 91 thereof, and a retracted position in which the travel surface 20 is distant therefrom such as to leave open between the front edge of the travel surface and the corresponding edge of the die 9 at least one transverse region defining an overflow 21 for the fall of the material (see Figure 1).
In the embodiment shown in the figures, there is provided a movable frame 25 upperly carrying the table 22 and supported by and constrained to a fixed frame 30 in such a manner as to be able to slide relative thereto in only the longitudinal horizontal direction.
In detail, the movable frame 25 is rectangular and is positioned just above the fixed frame 30, which is also rectangular and is carried by a base structure 34 resting on the ground.
The movable frame 25 carries on each of its two longitudinal sides 26a a pair of idle wheels 27 of horizontal transverse axis, which rotate against the upper edge of a respective lower horizontal longitudinal rail 32 fixed to a respective longitudinal side 31a of the fixed frame 30. One of the two pairs of wheels 27 possesses an annular groove which engages the upper portion of the cross-section of the rail 32. The other pair of wheels 27, positioned on the opposite side 26a, has a flat profile and rolls on an equally flat rail 32.
The movable frame 25 also carries, on each of its two longitudinal sides 26a, a central wheel 28 which rolls against the lower edge of a respective horizontal longitudinal rail 33 fixed to a respective longitudinal side 31a and positioned above the rail 28. By virtue of the constraint produced by the wheels 27 and 28 in combination with the rails 32 and 33, the frame 25 can slide only in the direction of these rails (ie in a horizontal longitudinal direction).
In detail, in the embodiment shown in the figures, on each side 26a of the movable frame 26 there is positioned a horizontal beam 251 to which a pair of wheels 27 is applied (see Figures 3 and 4). The wheels 28 are carried by two vertical angular plates 252 extending downwards from the lower side of the beans 251. On each longitudinal side 31a of the fixed frame 30 there is positioned a horizontal beam 301 to which a longitudinal element 302 parallel to the beam is fixed and carries on its upper edge the rail 32 and on its lower edge the rail 33.
The movable frame 25 also carries, supported by two central angular plates 252, an idle transverse shaft 35 onto the ends of which there are keyed two gearwheels 36 which engage respective horizontal longitudinal racks 37 fixed to the fixed frame 30 parallel to the direction of movement of the movable frame 25. The constraint provided by the gearwheels 36 acting on the racks 37 ensures that, while moving, the movable frame 25 remains rigorously parallel to itself (translational movement) without even the smallest rotation about the vertical axis of the frame 25.
The device also comprises means for moving the travel surface 20 synchronously with the movement of the carriage 10 such that the return travel of the carriage 10 takes place while the travel surface 20 is in its retracted position, whereas its forward travel takes place while the surface 20 is in its position adjacent to the die 9.
According to a preferred (but not exclusive) embodiment, a pneumatic cylinder-piston unit 41 is provided to move the movable frame 25 relative to the fixed frame 30 along the horizontal longitudinal direction, in order to move the travel surface 20 away from and towards the die 9. In detail, the cylinder-piston unit 41 has a cylindrical body 42 carrying a pair of transverse pins 43 pivoted on elements 44 fixed to the fixed frame 30, and a movable rod 45 hinged on a transverse pin 46 carried by a bracket 47 fixed to the movable frame 25.
In combination with the cylinder-piston unit 41 there operate two pairs of travel stop means 58 and 59 with associated impact dampers 50, to define the advanced and retracted positions of the travel surface 20.
In detail, each travel stop means 58 and 59 comprises two parts, one fixed to the movable frame 25 and the other fixed to the fixed frame 30, they being positioned in mutual relationship such that they abut one against the other to define said advanced and retracted positions. The damper means 50 each comprise a horizontal longitudinal rod 51 carried telescopically by a member 52 fixed to the fixed frame 30, and carrying at its free end a striker member 53 (of elastomeric material) and a compression spring 54 precompressed between the member 52 and the striker member 53. This makes contact with a downwardly projecting stop element 55 fixed to the movable frame 25.
Two of the means 50 operate as decelerators when the frame 25 moves in one direction, the other two operating as decelerators when the frame 25 moves in the opposite direction, and being positioned in such geometrical relationship that the travel surface 20 moves between said two end positions, ie advanced and retracted, defined by the travel limit means 58 and 59, these positions being attained without jolting by virtue of the damping action of the springs 54 and the fluid system contained within the member 52.
In operation, the carriage 10 is firstly brought into its retracted position, completely above the travel surface 20, where it receives the material with which to load the die 9 by the means 16. During this stage the lower end of the loading compartment 11 is closed by the surface 20.
The carriage 10 is then slid into its advanced position above the cavity 8 in the die 9. The travel surface 20 is in its position adjacent to the upper edge of the die 9 and the loading compartment 11 is closed lowerly by the surface 20 and by the upper surface 91 of the die 9. When above the cavity 8 the material falls from the compartment 11 and fills the cavity.
On the return travel of the carriage 10 the travel surface 20 is pulled rearwards into its retracted position, to open the overflow 21. The entire loading compartment 11 and the scraper means 17 therefore slide above the overflow 21 and allow the residual material (which has not been deposited in the cavity 8) to fall through the overflow.
Consequently, at each cycle the loading compartment 11 and the scraper means 17 are completely emptied, as required.
The material which falls through the overflow 21 can be collected, for example by a collection hopper 61, and possibly be recirculated.
Means are provided for sensing the position of the carriage 10 (of known type, not shown in the figures), coordinated with the control means for the cylinder-piston unit 41, to move the travel surface 20 (in order to close and open the overflow 21) synchronously with the movement of the carriage 10.
Numerous modifications of a practical and applicational nature can be made to the device of the invention, but without leaving the scope of the inventive idea as claimed below.
For example, only a portion of the travel surface 20 could be moved to form the overflow. Moreover this portion could rotate instead of translate.

Claims

A device far loading material into the die cavity of a mould (9), in particular for pressing ceramic tiles, comprising a loading carriage (10) having a loading compartment (11) with its lower end open and driven with reciprocating movement in a longitudinal direction between a retracted position in which the loading compartment is fed with the tile material, and an advanced position in which it releases the material into the die cavity through its open lower end, and having a scraper means (17) for scraping the material in the die cavity, and comprising, positioned adjacent to and coplanar with the upper surface of the die, a travel surface (20) along which the carriage loading compartment (11) and the scraper means (17) sealedly slide and which closes the lower end of the loading compartment (11), characterised in that: all or a part said travel surface (20) is movable in such a manner as to define at least one transverse overflow (21) for the fall of the material, involving the entire width of the carriage loading compartment (11) and of the scraper means (17), means (41) being provided for moving all or part of the travel surface (20) in order to open and respectively close said overflow (21), and being coordinated with the movement of the carriage (10) in such a manner that the carriage return travel takes place while the overflow is open, whereas its outward travel takes place while the overflow is closed.
A device as claimed in claim 1, characterised in that the entire travel surface (20) is movable in a horizontal longitudinal direction between an advanced position in which it is adjacent to the die (9) and a retracted position in which it is distant therefrom so as to leave open at least one transverse region (21) between the front edge of the travel surface and the corresponding edge of the die, to define said overflow (21) for the fall of the material, means being provided to drive the travel surface synchronously with the carriage movement such that the carriage return travel takes place while the travel surface is in its retracted position, while the carriage outward travel takes place while the travel surface is in its position adjacent to the die.
A device as claimed n claim 1, characterised by comprising, carrying the travel surface, a movable frame (25) constrained to a fixed frame (30) in such a manner as to be able to slide relative thereto in only the longitudinal horizontal direction.
A device as claimed in claim 3, characterised in that the movable frame (25) carries an idle transverse shaft (35), onto the ends of which there are keyed two gearwheels (36) which engage respective horizontal longitudinal racks (37) fixed to the fixed frame (30), parallel to the direction of movement the movable frame.
A device as aimed in claim 3, characterised by comprising a pneumatic cylinder-piston unit (41) arranged to move the movable frame (25) relative to the fixed frame (30) along the horizonta1 longitudinal direction such as to move the travel surface away from and towards the die, and associated with impact damping means (50) which define the advanced and retracted positions of the travel surface.