阅读说明：本技术 一种透水瓷砖通用胚体及其成型方法 (Universal blank for water permeable ceramic tiles and forming method thereof ) 是由 梁英强 于 2021-07-26 设计创作，主要内容包括：本发明公开了一种透水瓷砖通用胚体及其成型方法,涉及透水瓷砖技术领域,为解决现有的透水瓷砖,在成型加工过程中,其加工步骤较多,使得胚体成型效率与质量下降的问题。包括以下重量百分比组分：煤矸石5-8％；天然砂10-15％；黏土23-36％；长石8-16％；硅藻土5-10％；磷酸盐8-12％；防冻剂2-5％；矿渣8-2％；六亚甲基四胺固化剂0.6-1.3％；粉煤灰5-3％,先是利用混合液罐上的多个注入端,连接多个浆液管,再将处理控制结构上的检修板打开,检修内部情况,更换不同的模板盒,调整PLC控制器参数,控制整体开始运转,浆液进入混合液罐内部,第二电机驱动搅拌杆,将各种不同浆液快速混合搅拌,再经过输料过滤结构内部的多个粗滤网与细滤网,形成制备材料处理,进行深层材料过滤。(The invention discloses a universal blank body for a water permeable ceramic tile and a forming method thereof, relates to the technical field of water permeable ceramic tiles, and aims to solve the problem that the forming efficiency and quality of the blank body are reduced due to more processing steps in the forming and processing process of the existing water permeable ceramic tile. Comprises the following components in percentage by weight: 5-8% of coal gangue; 10-15% of natural sand; 23-36% of clay; 8-16% of feldspar; 5-10% of diatomite; 8-12% of phosphate; 2-5% of an antifreezing agent; 8-2% of slag; 0.6 to 1.3 percent of hexamethylene tetramine curing agent; 5-3% of fly ash, firstly, a plurality of injection ends on the mixed liquid tank are utilized to connect a plurality of slurry pipes, then, an access panel on a processing control structure is opened to examine and repair the internal condition, different template boxes are replaced, parameters of a PLC (programmable logic controller) are adjusted, the whole operation of control is started, slurry enters the interior of the mixed liquid tank, a second motor drives a stirring rod to rapidly mix and stir various different slurries, and then, a plurality of coarse filtration screens and fine filtration screens in the conveying filtration structure are utilized to form preparation material processing and carry out deep material filtration.)

1. The universal blank for the water permeable ceramic tile is characterized by comprising the following components in percentage by weight:

5-8% of coal gangue;

10-15% of natural sand;

23-36% of clay;

8-16% of feldspar;

5-10% of diatomite;

8-12% of phosphate;

2-5% of an antifreezing agent;

8-2% of slag;

0.6 to 1.3 percent of hexamethylene tetramine curing agent;

5-3% of fly ash.

2. The method for forming the universal blank for water permeable tiles according to claim 1, comprising the following steps:

step 1: firstly, connecting a plurality of slurry pipes by using a plurality of injection ends (2) on a mixed liquid tank (1) on a forming device, opening an inspection plate (15) on a processing control structure (4), inspecting the internal condition, and replacing different template boxes (28);

step 2: adjusting parameters of a PLC (programmable logic controller) (5), controlling the whole to start to operate, enabling the slurry to enter a mixed liquid tank (1), driving a stirring rod (20) by a second motor (19), rapidly mixing and stirring various different slurries, and enabling the slurries to pass through a plurality of coarse filter screens (22) and fine filter screens (23) in a material conveying and filtering structure (3) to form preparation material treatment, filtering deep materials and enabling the prepared materials to flow into a liquid storage tank (24);

and step 3: then, a power supply (25) is used for driving a vibration sound wave device (40) to carry out deep treatment on the liquid in the liquid storage tank (24), a plurality of liquid level spray heads (26) are sprayed into the template box (28), meanwhile, a temperature control pressure device (27) is used for carrying out pressure temperature control on the inside, the temperature control forming is carried out after a period of time, and an electromagnetic control valve (29) is opened;

and 4, step 4: the template box (28) falls on the transmission structure (8), the template box is transmitted through the transmitter (36), the template box (28) is sent to the lower part of the polishing carrier (17), the first motor (9) drives the telescopic cylinder (31) to drive the polishing and drawing-cutting structure (7) to descend, the wireless linkage sensor (32) drives the polishing carrier (17) to operate, meanwhile, the rotator (30) drives the rotating teeth (33), a blank in the template box (28) is cut, and the laser identifier (38) is utilized to monitor the whole cutting process;

and 5: when cutting, the air extractor (34) starts to operate, and the cutting waste residues are sucked into the material receiving box (37) for recycling and storage;

wherein, former includes mixed fluid reservoir (1), defeated material filtration (3) is installed to one side of mixed fluid reservoir (1), one side below of defeated material filtration (3) is provided with idiosome shaping processing structure (6), one side of idiosome shaping processing structure (6) is installed and is polished and is drawn cutting structure (7), the below of polishing and drawing cutting structure (7) is provided with transmission structure (8).

3. The universal blank for water permeable ceramic tiles and the forming method thereof according to claim 2, wherein: injection end (2) are installed to the upper end of mixed fluid reservoir (1), the upper end of injection end (2) is provided with filling opening (10), and filling opening (10) and the upper end integrated into one piece setting of injection end (2), support frame (11) are installed to the lower extreme of mixed fluid reservoir (1), and support frame (11) and the lower extreme welded connection of mixed fluid reservoir (1), the inside of mixed fluid reservoir (1) is provided with puddler (20), second motor (19) are installed to the one end of puddler (20), and the one end welded connection of second motor (19) and puddler (20).

4. The universal blank for water permeable ceramic tiles and the forming method thereof according to claim 2, wherein: self-checking structure (13) are installed in the outside of defeated material filtration (3), the inside of defeated material filtration (3) is provided with coarse strainer (22), and coarse strainer (22) and the inside welded connection of defeated material filtration (3), fine screen (23) are installed to the below of coarse strainer (22).

5. The universal blank for water permeable ceramic tiles and the forming method thereof according to claim 4, wherein: one end of the self-checking structure (13) is provided with a flow meter (21), and the flow meter (21) is connected with one end of the self-checking structure (13) in a welding mode.

6. The universal blank for water permeable ceramic tiles and the forming method thereof according to claim 2, wherein: processing control structure (4) are installed to the top of structure (6) is handled in the idiosome shaping, the outer wall that structure (6) was handled in the idiosome shaping is provided with water proof coating (14), and water proof coating (14) and idiosome shaping processing structure (6) integrated into one piece setting, heat dissipation end (12) are installed to the outer end of idiosome shaping processing structure (6), the one end of heat dissipation end (12) is provided with accuse temperature pressure ware (27), and the one end welded connection of accuse temperature pressure ware (27) and heat dissipation end (12), the internally mounted of structure (6) is handled in the idiosome shaping has template box (28), the front end of idiosome shaping processing structure (6) is provided with PLC controller (5).

7. The universal blank for water permeable ceramic tiles and the forming method thereof according to claim 6, wherein: access panel (15) are installed to the top of handling control structure (4), the inside of handling control structure (4) is provided with liquid storage tank (24), the lower extreme of liquid storage tank (24) is provided with liquid level injection head (26), liquid level response interceptor (39) are installed to the one end of liquid level injection head (26), and the one end welded connection of liquid level response interceptor (39) and liquid level injection head (26), the top of liquid storage tank (24) is provided with power supply (25), vibrations acoustic wave ware (40) are installed to one side of power supply (25), and vibrations acoustic wave ware (40) are through electric wire circuit (41) and power supply (25) electric connection.

8. The universal blank for water permeable ceramic tiles and the forming method thereof according to claim 2, wherein: polish and draw one side of cutting structure (7) and install transmission sealed end (16), the inside of transmission sealed end (16) is provided with solenoid electric valve (29), and solenoid electric valve (29) and transmission sealed end (16) integrated into one piece set up, polish and draw the centre of cutting structure (7) to install laser identification ware (38), and laser identification ware (38) and polish and draw the centre welded connection who cuts structure (7), polish and draw the surface of cutting structure (7) to be provided with damper plate (18), the carrier (17) of polishing is installed to one side of laser identification ware (38), one side of carrier (17) of polishing is provided with first motor (9), telescopic cylinder (31) are installed to the one end of first motor (9).

9. The universal blank for water permeable ceramic tiles and the forming method thereof according to claim 8, wherein: the wireless linkage inductor (32) is installed in the middle of the grinding carrier (17), a rotator (30) is arranged at one end of the grinding carrier (17), and a rotating tooth (33) is installed at one end of the rotator (30).

10. The universal blank for water permeable ceramic tiles and the forming method thereof according to claim 2, wherein: conveyer (36) is installed to the one end of transmission structure (8), and the one end welded connection of conveyer (36) and transmission structure (8), the inner wall of transmission structure (8) is provided with wear-resistant coating (35), material collecting box (37) is installed to the below of transmission structure (8), the one end of material collecting box (37) is provided with aspirator (34), and the one end welded connection of aspirator (34) and material collecting box (37).

Technical Field

The invention relates to the technical field of water permeable tiles, in particular to a universal blank of a water permeable tile and a forming method thereof.

Background

The ceramic tile is a common building decoration material for laying a ground or a wall, is smooth, flat, beautiful and comfortable, and is widely applied to inner and outer walls and indoor floor tiles, and the general decoration ceramic tiles are required to be water-impermeable (the water permeability is not more than 20%), so that the water-impermeable ensures the compactness of the surface of the ceramic tile, thereby ensuring the strength requirement of a ceramic tile blank body, but the water-impermeable limits the application range of the ceramic tile, such as roads, teeth of gardens, even park roads and the like, and the surface is easy to generate water accumulation to cause skidding due to poor water absorption of ceramics.

In the existing permeable ceramic tile, the processing steps are more in the forming and processing process, so that the forming efficiency and quality of a blank body are reduced; therefore, the existing requirements are not met, and a universal blank for the water-permeable ceramic tile and a forming method thereof are provided.

Disclosure of Invention

The invention aims to provide a universal blank for a water permeable ceramic tile and a forming method thereof, and aims to solve the problem that the forming efficiency and quality of the blank are reduced due to more processing steps in the forming and processing process of the existing water permeable ceramic tile in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme: a general blank for water permeable ceramic tiles comprises the following components in percentage by weight:

5-8% of coal gangue;

10-15% of natural sand;

23-36% of clay;

8-16% of feldspar;

5-10% of diatomite;

8-12% of phosphate;

2-5% of an antifreezing agent;

8-2% of slag;

0.6 to 1.3 percent of hexamethylene tetramine curing agent;

5-3% of fly ash.

Preferably, the forming method of the universal blank for the water permeable tile comprises the following steps:

step 1: firstly, connecting a plurality of slurry pipes by utilizing a plurality of injection ends on a mixed liquid tank on a forming device, then opening an overhaul panel on a processing control structure, overhauling the internal condition, and replacing different template boxes;

step 2: adjusting parameters of a PLC controller, controlling the whole to start to operate, enabling the slurry to enter a mixed liquid tank, driving a stirring rod by a second motor, quickly mixing and stirring various slurries, enabling the slurries to pass through a plurality of coarse filter screens and fine filter screens in a conveying and filtering structure to form preparation material treatment, filtering deep materials, and enabling the prepared materials to flow into a liquid storage tank;

and step 3: then, a power supply is used for driving a vibration acoustic wave device to carry out deep treatment on liquid in the liquid storage tank, the liquid is sprayed into the template box by a plurality of liquid level spraying heads, meanwhile, a temperature control pressure device carries out pressure temperature control on the inside, after a period of time of temperature control forming, an electromagnetic control valve is opened;

and 4, step 4: the template box falls on the transmission structure, is transmitted by the transmitter and is sent to the lower part of the polishing carrier, the first motor drives the telescopic cylinder to drive the polishing and drawing-cutting structure to descend, the wireless linkage sensor drives the polishing carrier to run, meanwhile, the rotator drives the rotary teeth to cut the blank in the template box, and the laser identifier is utilized to monitor the whole cutting process;

and 5: when cutting, the air extractor starts to operate, and the cutting waste residues are sucked into the material receiving box for recycling and storing;

the forming equipment comprises a mixed liquid tank, a material conveying filtering structure is installed on one side of the mixed liquid tank, a blank forming processing structure is arranged below one side of the material conveying filtering structure, a polishing and cutting structure is installed on one side of the blank forming processing structure, and a transmission structure is arranged below the polishing and cutting structure.

Preferably, the injection end is installed to the upper end of mixed fluid reservoir, the upper end of injection end is provided with the filling opening, and the upper end integrated into one piece setting of filling opening and injection end, the support frame is installed to the lower extreme of mixed fluid reservoir, and the lower extreme welded connection of support frame and mixed fluid reservoir, the inside of mixed fluid reservoir is provided with the puddler, the second motor is installed to the one end of puddler, and the one end welded connection of second motor and puddler.

Preferably, the self-checking structure is installed in defeated material filtration's the outside, defeated material filtration's inside is provided with the coarse strainer, and the coarse strainer is connected with defeated material filtration's internal weld, fine filter screen is installed to the below of coarse strainer.

Preferably, one end of the self-checking structure is provided with a flow meter, and the flow meter is connected with one end of the self-checking structure in a welding mode.

Preferably, the processing control structure is installed to the top that the structure was handled in the idiosome shaping, the outer wall that the structure was handled in the idiosome shaping is provided with waterproof coating, and waterproof coating and idiosome shaping processing structure integrated into one piece setting, the heat dissipation end is installed to the outer end that the structure was handled in the idiosome shaping, the one end of heat dissipation end is provided with accuse temperature pressure gauge, and the one end welded connection of accuse temperature pressure gauge and heat dissipation end, the internally mounted of structure is handled in the idiosome shaping has the template box, the front end that the structure was handled in the idiosome shaping is provided with the PLC controller.

Preferably, the access panel is installed to the top of process control structure, the inside of process control structure is provided with the liquid storage box, the lower extreme of liquid storage box is provided with the liquid level injector head, liquid level response interceptor is installed to the one end of liquid level injector head, and the one end welded connection of liquid level response interceptor and liquid level injector head, the top of liquid storage box is provided with the powersupply, vibrations acoustic wave ware is installed to one side of powersupply, and vibrations acoustic wave ware passes through electric wire line and powersupply electric connection.

Preferably, polish and draw one side of cutting the structure and install the transmission sealed end, the inside of transmission sealed end is provided with solenoid electric valve, and solenoid electric valve and the setting of transmission sealed end integrated into one piece, polish and draw the centre of cutting the structure and install laser identification ware, and laser identification ware and polish and draw the middle welded connection who cuts the structure, polish and draw the surface of cutting the structure and be provided with the damper plate, the carrier of polishing is installed to one side of laser identification ware, one side of the carrier of polishing is provided with first motor, telescopic cylinder is installed to the one end of first motor.

Preferably, the wireless linkage inductor is installed to the centre of the carrier of polishing, the one end of the carrier of polishing is provided with the circulator, rotatory tooth is installed to the one end of circulator.

Preferably, the conveyer is installed to transmission structure's one end, and the one end welded connection of conveyer and transmission structure, transmission structure's inner wall is provided with wear-resistant coating, the material receiving box is installed to transmission structure's below, the one end of material receiving box is provided with the aspirator, and the aspirator and the one end welded connection of material receiving box.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the invention, through the mutual matching of the mixed liquid tank, the material conveying filtering structure, the blank forming processing structure and the polishing, drawing and cutting structure, the deep control can be performed on the material, the forming and processing efficiency of the blank is improved, the parameters of the PLC are adjusted, the whole operation is controlled, the slurry enters the mixed liquid tank, the stirring rod is driven by the second motor to rapidly mix and stir various different slurries, the prepared material is processed through a plurality of coarse filtering nets and fine filtering nets in the material conveying filtering structure, the deep material is filtered, the prepared material flows into the liquid storage tank, the material is processed, the formation of bubbles in the preparation process is avoided, and the quality of the blank is ensured.

2. The template box is sprayed into by a plurality of liquid level injector heads, the temperature control pressure gauge carries out pressure temperature control to inside simultaneously, through the shaping of a period of time temperature control, solenoid electric valve opens, the template box falls on the transmission structure, carry out the transmission through the transmitter, send the template box to under the carrier of polishing, first motor drive telescopic cylinder drives and polishes and draws the structure of cutting and descend, the wireless linkage inductor drives the carrier operation of polishing, the circulator drives rotatory tooth simultaneously, cut the idiosome in the template box, utilize laser recognizer, the whole process of cutting of monitoring, to ceramic tile idiosome fly-cutting, the follow-up processing of being convenient for, and the machining efficiency is improved.

3. When cutting, the aspirator begins to operate, will cut the waste residue, inhales in the collecting box, carries out the secondary and retrieves and deposit, avoids extravagant material, increases the feature of environmental protection, and the flow counter that sets up controls the flow of liquid, detects, avoids the pipe blockage, and the wear-resistant coating and the shock attenuation board that set up reduce the vibrations to equipment, promote the protectiveness.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a schematic cross-sectional view of the present invention;

FIG. 3 is a schematic top view of the present invention;

FIG. 4 is a partial schematic view of a polishing and stretch-cutting structure according to the present invention;

FIG. 5 is a schematic view of the overall process of the general blank for water permeable tiles and the forming method thereof according to the present invention;

in the figure: 1. a mixed liquid tank; 2. an injection end; 3. a material conveying filtering structure; 4. processing the control structure; 5. a PLC controller; 6. a blank forming processing structure; 7. polishing the stretch-cutting structure; 8. a transmission structure; 9. a first motor; 10. an injection port; 11. a support frame; 12. a heat dissipation end; 13. a self-checking structure; 14. a water-resistant coating; 15. an access panel; 16. a transfer seal end; 17. grinding the carrier; 18. a damper plate; 19. a second motor; 20. a stirring rod; 21. a flow meter; 22. coarse filtration; 23. a fine filter screen; 24. a liquid storage tank; 25. a power supply; 26. a liquid level injector head; 27. a temperature and pressure controller; 28. a template box; 29. an electromagnetic control valve; 30. a rotator; 31. a telescopic cylinder; 32. a wireless linkage sensor; 33. rotating the teeth; 34. an air extractor; 35. a wear-resistant coating; 36. a transmitter; 37. a material receiving box; 38. a laser identifier; 39. a liquid level sensing cutter; 40. a vibrating acoustic wave; 41. and (4) electric wire lines.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

Referring to fig. 1-5, an embodiment of the present invention is shown: a general blank for water permeable ceramic tiles comprises the following components in percentage by weight:

5-8% of coal gangue;

10-15% of natural sand;

23-36% of clay;

8-16% of feldspar;

5-10% of diatomite;

8-12% of phosphate;

2-5% of an antifreezing agent;

8-2% of slag;

0.6 to 1.3 percent of hexamethylene tetramine curing agent;

5-3% of fly ash.

Further, the forming method of the universal blank body of the water permeable ceramic tile comprises the following steps:

step 1: firstly, connecting a plurality of slurry pipes by using a plurality of injection ends 2 on a mixed liquid tank 1 on a forming device, opening an overhaul panel 15 on a processing control structure 4, overhauling the internal condition, and replacing different template boxes 28;

step 2: adjusting parameters of a PLC (programmable logic controller) 5, controlling the whole to start to operate, enabling the slurry to enter the mixed liquid tank 1, driving a stirring rod 20 by a second motor 19, rapidly mixing and stirring various slurries, enabling the slurries to pass through a plurality of coarse filter screens 22 and fine filter screens 23 in a conveying and filtering structure 3 to form preparation material treatment, filtering deep materials, and enabling the slurries to flow into a liquid storage tank 24;

and step 3: then the power supply 25 is used for driving the vibration acoustic wave device 40 to carry out deep treatment on the liquid in the liquid storage tank 24, the liquid is sprayed into the template box 28 by the plurality of liquid level spraying heads 26, meanwhile, the temperature control pressure device 27 carries out pressure temperature control on the inside, after a period of time, the temperature control molding is carried out, and the electromagnetic control valve 29 is opened;

and 4, step 4: the template box 28 falls on the transmission structure 8 and is transmitted by the transmitter 36, the template box 28 is sent to the lower part of the polishing carrier frame 17, the first motor 9 drives the telescopic cylinder 31 to drive the polishing and drawing-cutting structure 7 to descend, the wireless linkage sensor 32 drives the polishing carrier frame 17 to operate, meanwhile, the rotator 30 drives the rotating teeth 33 to cut the blank in the template box 28, and the laser identifier 38 is utilized to monitor the whole cutting process;

and 5: when cutting, the air extractor 34 starts to operate, and the cutting waste residues are sucked into the material receiving box 37 for recycling and storage;

wherein, former includes mixed fluid reservoir 1, defeated material filtration 3 is installed to one side of mixed fluid reservoir 1, one side below of defeated material filtration 3 is provided with idiosome shaping processing structure 6, one side of idiosome shaping processing structure 6 is installed and is polished and draw and cut structure 7, the below of polishing drawing and cutting structure 7 is provided with transport structure 8.

Further, injection end 2 is installed to the upper end of mixed liquid jar 1, the upper end of injection end 2 is provided with filling opening 10, and filling opening 10 and the upper end integrated into one piece setting of injection end 2, support frame 11 is installed to the lower extreme of mixed liquid jar 1, and support frame 11 and the lower extreme welded connection of mixed liquid jar 1, the inside of mixed liquid jar 1 is provided with puddler 20, second motor 19 is installed to the one end of puddler 20, and the one end welded connection of second motor 19 and puddler 20.

Further, self-checking structure 13 is installed in defeated material filtration 3's the outside, defeated material filtration 3's inside is provided with coarse strainer 22, and coarse strainer 22 and defeated material filtration 3's inside welded connection, fine filter screen 23 is installed to coarse strainer 22's below.

Further, one end of self-checking structure 13 is provided with flow meter 21, and flow meter 21 is welded with one end of self-checking structure 13.

Further, processing control structure 4 is installed to the top of structure 6 is handled in the idiosome shaping, the outer wall that structure 6 was handled in the idiosome shaping is provided with water proof coating 14, and water proof coating 14 and the setting of idiosome shaping processing structure 6 integrated into one piece, heat dissipation end 12 is installed to the outer end of structure 6 is handled in the idiosome shaping, the one end of heat dissipation end 12 is provided with accuse temperature pressure gauge 27, and just accuse temperature pressure gauge 27 and the one end welded connection of heat dissipation end 12, the internally mounted of structure 6 is handled in the idiosome shaping has template box 28, the front end of structure 6 is handled in the idiosome shaping is provided with PLC controller 5.

Further, access panel 15 is installed to the top of processing control structure 4, the inside of processing control structure 4 is provided with liquid storage box 24, liquid storage box 24's lower extreme is provided with liquid level injection head 26, liquid level response interceptor 39 is installed to liquid level injection head 26's one end, and liquid level response interceptor 39 and liquid level injection head 26's one end welded connection, liquid storage box 24's top is provided with power supply 25, vibrations acoustic wave ware 40 is installed to one side of power supply 25, and vibrations acoustic wave ware 40 passes through electric wire way 41 and power supply 25 electric connection.

Further, polish and draw one side of cutting structure 7 and install transmission sealed end 16, the inside of transmission sealed end 16 is provided with solenoid electric valve 29, and solenoid electric valve 29 and transmission sealed end 16 integrated into one piece set up, polish and draw the centre of cutting structure 7 and install laser identification ware 38, and laser identification ware 38 with polish and draw the middle welded connection who cuts structure 7, polish and draw the surface of cutting structure 7 and be provided with damper plate 18, the carrier 17 of polishing is installed to one side of laser identification ware 38, one side of carrier 17 of polishing is provided with first motor 9, telescopic cylinder 31 is installed to the one end of first motor 9.

Further, a wireless linkage sensor 32 is installed in the middle of the grinding carrier 17, a rotator 30 is arranged at one end of the grinding carrier 17, and a rotating tooth 33 is installed at one end of the rotator 30.

Further, transmitter 36 is installed to transmission structure 8's one end, and the one end welded connection of transmitter 36 and transmission structure 8, transmission structure 8's inner wall is provided with wear-resistant coating 35, material receiving box 37 is installed to transmission structure 8's below, material receiving box 37's one end is provided with air extractor 34, and air extractor 34 and material receiving box 37's one end welded connection.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.