阅读说明：本技术 一种发泡材料注塑用降温装置及其使用方法 (Cooling device for injection molding of foaming material and use method thereof ) 是由 汪彪 汪龙 于 2020-10-28 设计创作，主要内容包括：本发明公开了一种发泡材料注塑用降温装置及其使用方法,涉及发泡材料加工领域,为解决现有技术中的现有的发泡材料注塑工作中,材料定型后,无法迅速冷却,导致工作效率低,且冷却效果差,导致成型后的发泡材料容易变形的问题。所述冷却箱的内部两侧均设置有降温箱体,两个所述降温箱体之间的下方安装有风冷散热器,所述下模具位于冷却箱的内部,所述降温箱体的内部安装有冷却水箱,所述下模具的两侧均设置有软管,所述下模具的内部上方设置有模具框体,所述模具框体的内部设置有注塑槽,且所述模具框体的内部下方设置有横向水冷管,所述模具框体的内部两侧均设置有纵向水冷管,所述纵向水冷管和横向水冷管的两端均设置有多通管。(The invention discloses a cooling device for foam material injection molding and a use method thereof, relates to the field of foam material processing, and aims to solve the problems that in the prior art, in the existing foam material injection molding work, the material cannot be rapidly cooled after being shaped, so that the work efficiency is low, the cooling effect is poor, and the molded foam material is easy to deform. The inside both sides of cooler bin all are provided with the cooling box, two forced air cooling radiator is installed to below between the cooling box, the bed die is located the inside of cooler bin, the internally mounted of cooling box has coolant tank, the both sides of bed die all are provided with the hose, the inside top of bed die is provided with the mould framework, the inside of mould framework is provided with the groove of moulding plastics, just the inside below of mould framework is provided with horizontal water-cooled tube, the inside both sides of mould framework all are provided with vertical water-cooled tube, the both ends of vertical water-cooled tube and horizontal water-cooled tube all are provided with the multi-ported pipe.)

1. The utility model provides a foam material is moulded plastics and is used heat sink, includes cooler bin (2), bed die (7) and last mould (8), its characterized in that: the cooling device is characterized in that cooling boxes (16) are arranged on two sides of the interior of the cooling box (2), an air cooling radiator (17) is installed below the cooling boxes (16), the lower die (7) is located inside the cooling box (2), a cooling water tank (27) is installed inside the cooling boxes (16), hoses are arranged on two sides of the lower die (7) and extend to the interior of the cooling boxes (16) to be hermetically connected with the cooling water tank (27), a die frame body (22) is arranged above the interior of the lower die (7), an injection molding groove (23) is formed in the interior of the die frame body (22), transverse water-cooling pipes (25) are arranged below the interior of the die frame body (22), longitudinal water-cooling pipes (26) are arranged on two sides of the interior of the die frame body (22), and multi-way pipes (24) are arranged at two ends of the longitudinal water-cooling pipes (26) and the transverse water-cooling pipes (25), the multi-way pipe (24) is connected with the hose in a sealing way.

2. The cooling device for injection molding of the foam material according to claim 1, wherein: mounting panel (5) are installed to the up end of cooler bin (2), mounting panel (5) are connected with cooler bin (2) through the fixed screw, fixed lagging (6) are installed to the top of mounting panel (5), fixed lagging (6) and mounting panel (5) welded connection, the inside of fixed lagging (6) is provided with the opening, and the shape of opening is the same with the shape of bed die (7) and last mould (8) respectively, the lower extreme of cooler bin (2) is provided with base (1).

3. The cooling device for injection molding of the foam material according to claim 2, wherein: the utility model discloses an electronic support structure of a mould, including bed die (7), bed die (7) and last mould (8), the outside of bed die (7) and last mould (8) is provided with limit guide (10), limit guide (10) set up structure as an organic whole with bed die (7) and last mould (8), just bed die (7) and last mould (8) all are through limit guide (10) and fixed lagging (6) sliding connection, just electronic jar of second (18) are all installed to the lower extreme both sides of bed die (7), the both ends of electronic jar of second (18) respectively with bed die (7) and base (1) fixed connection.

4. The cooling device for injection molding of the foam material according to claim 1, wherein: thimble (12) are installed to the upper end of going up mould (8), fixed plate (11) are installed to the top of thimble (12), fixed plate (11) and thimble (12) fixed connection, just thimble (12) run through last mould (8) and last mould (8) sliding connection, go up the upper end center of mould (8) and install first electronic jar (13), fixed sleeve (15) are installed to the lower extreme of first electronic jar (13), fixed sleeve (15) are connected with last mould (8) through the fixed screw, the upper end and fixed plate (11) fixed connection of first electronic jar (13), just install bin (14) in the top of fixed plate (11).

5. The cooling device for injection molding of the foam material according to claim 1, wherein: the outer portion of the upper die (8) is provided with an injection molding hole (9), the injection molding hole (9) is communicated with the upper die (8) and an injection molding groove (23), the injection molding groove (23) and a die frame body (22) are arranged into an integral structure, the die frame body (22) and a lower die (7) are arranged into an integral structure, the transverse water-cooling pipe (25) and the longitudinal water-cooling pipe (26) are respectively provided with a plurality of, and the plurality of, one ends of the transverse water-cooling pipe (25) and the longitudinal water-cooling pipe (26) are respectively embedded into the die frame body (22) and are fixedly connected with the die frame body (22).

6. The cooling device for injection molding of the foam material according to claim 1, wherein: the internally mounted of coolant tank (27) has miniature pump (28), miniature pump (28) and coolant tank (27) fixed connection, just miniature pump (28) and hose sealing connection, cooling fin (29) are installed to the below of miniature pump (28), connection water pipe (3) are all installed to the both sides of coolant tank (2), connection water pipe (3) and coolant tank (27) sealing connection, two install connecting pipe body (20) between coolant tank (27), connecting pipe body (20) run through inside and air-cooled radiator (17) fixed connection of air-cooled radiator (17).

7. The cooling device for injection molding of the foam material according to claim 1, wherein: the surface of forced air cooling radiator (17) is provided with vent (19), the surface of cooler bin (2) is provided with air vent (4), air vent (4) link up with vent (19), just forced air cooling radiator (17) include fan motor (30), cooling fan (31) and filter screen (32), filter screen (32) are located the inside upper end of forced air cooling radiator (17), inlet scoop (21) are installed to the upper end of filter screen (32), the position of inlet scoop (21) is corresponding with the position of bed die (7).

8. A use method of a cooling device for foam material injection molding is realized based on any one of claims 1 to 7, and is characterized by comprising the following steps:

the method comprises the following steps: firstly, fixing and positioning a fixing plate (11) and a base (1), extending a first electric cylinder (13) to enable an upper die (8) and a lower die (7) to be closely attached, and performing injection molding work on a foaming material through an injection molding hole (9);

step two: after injection molding, the second electric cylinder (18) is contracted to drive the lower mold (7) to move to the inside of the cooling box (2), a power supply of a fan motor (30) and a micro water pump (28) is turned on, cooling water cooled by a cooling fin (29) in the cooling water box (27) is guided into a multi-way pipe (24) in the lower mold (7) through a hose, the multi-way pipe (24) distributes the cooling water to a transverse water-cooling pipe (25) and a longitudinal water-cooling pipe (26), and the mold frame body (22) is cooled through the transverse water-cooling pipe (25) and the longitudinal water-cooling pipe (26);

step three: the cooling fan (31) sucks the heat emitted from the surface of the lower die (7) out of the cooling box (2) to dissipate the heat of the whole lower die (7);

step four: after heat dissipation, the second electric cylinder (18) pushes the lower die (7), and after the lower die (7) and the upper die (8) slide out of the fixed sleeve plate (6), the first electric cylinder (13) is contracted, and the formed foaming material is taken out.

Technical Field

The invention relates to the technical field of processing of foaming materials, in particular to a cooling device for injection molding of a foaming material and a using method thereof.

Background

The soft foaming material has wide application, is closely related to the basic industry of national economy, and keeps the stable and continuous growth of about 20 percent for many years. The soft foaming material is prepared by adding a catalyst, a foam stabilizer, a foaming agent and other auxiliary materials into raw materials such as plastic and rubber, and then carrying out physical foaming or cross-linking foaming to enable a large amount of fine foams to appear in the plastic and the rubber, so that the volume is increased, the density is reduced, the soft foaming material has the advantages of light weight and good softness, has the functions of buffering, sound absorption, shock absorption, heat preservation, filtration and the like, and is widely applied to industries such as electronics, household appliances, automobiles, sports and leisure and the like. The foaming material, also called a foaming agent, refers to a substance capable of being gasified to generate bubbles inside a substance to be foamed into a porous substance, such as manufacturing foamed plastics, foamed rubber, foamed resin, foamed foods (steamed bread, steamed stuffed bun, bread, cake), and the like, and the foaming material can be classified into three types, i.e., chemical foaming material, physical foaming material, and surfactant.

The foamed plastic is produced by using synthetic resin as main material and through foaming to form plastic product with inside micropores. The foaming injection molding process is an innovative precise injection molding technology, breaks through a plurality of limitations of the traditional injection molding, can obviously reduce the weight of a finished piece, shortens the molding period, and greatly improves the buckling deformation and the dimensional stability of the finished piece. However, in the existing foaming material injection molding work, after the material is shaped, the material cannot be rapidly cooled, so that the working efficiency is low, the cooling effect is poor, the formed foaming material is easy to deform, and the processing quality is influenced; therefore, the market urgently needs to develop a cooling device for injection molding of a foaming material and a using method thereof to help people to solve the existing problems.

Disclosure of Invention

The invention aims to provide a cooling device for foam material injection molding and a using method thereof, and aims to solve the problems that in the existing foam material injection molding work in the background art, after a material is shaped, the material cannot be rapidly cooled, so that the work efficiency is low, the cooling effect is poor, and the molded foam material is easy to deform.

In order to achieve the purpose, the invention provides the following technical scheme: the utility model provides a cooling device for foam material is moulded plastics, includes cooler bin, bed die and last mould, the inside both sides of cooler bin all are provided with the cooling box, two air-cooled radiator is installed to below between the cooling box, the bed die is located the inside of cooler bin, the internally mounted of cooling box has coolant tank, the both sides of bed die all are provided with the hose, and the hose extends to the cooling box inside and coolant tank sealing connection, the inside top of bed die is provided with the mould framework, the inside of mould framework is provided with the groove of moulding plastics, just the inside below of mould framework is provided with horizontal water-cooled tube, the inside both sides of mould framework all are provided with vertical water-cooled tube, the both ends of vertical water-cooled tube and horizontal water-cooled tube all are provided with multi-ported tube, multi-ported tube and hose sealing connection.

Preferably, the mounting panel is installed to the up end of cooler bin, the mounting panel passes through the fixed screw and is connected with the cooler bin, fixed lagging is installed to the top of mounting panel, fixed lagging and mounting panel welded connection, the inside of fixed lagging is provided with the opening, and the shape of opening is the same with the shape of bed die and last mould respectively, the lower extreme of cooler bin is provided with the base.

Preferably, the outside of bed die and last mould is provided with limit guide, limit guide sets up structure as an organic whole with bed die and last mould, just bed die and last mould all pass through limit guide and fixed sleeve plate sliding connection, just the electronic jar of second is all installed to the lower extreme both sides of bed die, the both ends of the electronic jar of second respectively with bed die and base fixed connection.

Preferably, the thimble is installed to the upper end of going up the mould, the fixed plate is installed to the top of thimble, fixed plate and thimble fixed connection, just the thimble runs through the mould and goes up mould sliding connection, first electronic jar is installed at the upper end center of going up the mould, fixed sleeve is installed to the lower extreme of first electronic jar, fixed sleeve passes through the fixed screw and is connected with last mould, the upper end and the fixed plate fixed connection of first electronic jar, just the install bin is installed to the top of fixed plate.

Preferably, the outside of going up the mould is provided with the hole of moulding plastics, the hole of moulding plastics link up the mould and the groove intercommunication of moulding plastics, the groove of moulding plastics sets up structure as an organic whole with the mould framework, just the mould framework sets up structure as an organic whole with the bed die, horizontal water-cooled tube and vertical water-cooled tube all are provided with a plurality of, and a plurality of the one end of horizontal water-cooled tube and vertical water-cooled tube all imbeds inside and the mould framework fixed connection of mould framework.

Preferably, coolant tank's internally mounted has miniature pump, miniature pump and coolant tank fixed connection, just miniature pump and hose sealing connection, the cooling fin is installed to miniature pump's below, the connecting tube is all installed to the both sides of cooler bin, connecting tube and coolant tank sealing connection, two install the connecting tube body between the coolant tank, the connecting tube body runs through inside and air-cooled radiator fixed connection of forced air cooling radiator.

Preferably, the surface of forced air cooling radiator is provided with the vent, the surface of cooler bin is provided with the air vent, the air vent link up with the vent, just forced air cooling radiator includes fan motor, cooling fan and filter screen, the filter screen is located the inside upper end of forced air cooling radiator, the inlet scoop is installed to the upper end of filter screen, the position of inlet scoop is corresponding with the position of bed die.

A use method of a cooling device for foam material injection molding comprises the following steps:

the method comprises the following steps: extending the first electric cylinder to enable the upper die and the lower die to be closely attached, and performing injection molding on the foaming material through the injection molding hole;

step two: after injection molding, the second electric cylinder is contracted to drive the lower die to move to the inside of the cooling box, a power supply of a fan motor and a micro water pump is turned on, cooling water cooled by cooling fins in the cooling box is guided into a multi-way pipe in the lower die through a hose, the multi-way pipe divides the cooling water into a transverse water-cooling pipe and a longitudinal water-cooling pipe, and the die frame body is cooled through the transverse water-cooling pipe and the longitudinal water-cooling pipe;

step three: the cooling fan sucks the heat dissipated from the surface of the lower die out of the cooling box to dissipate the heat of the whole lower die;

step four: after the heat dissipation, promote the lower mould with the electronic jar of second, after the fixed lagging of lower mould and last mould roll-off, shrink first electronic jar, take out fashioned expanded material.

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

1. according to the invention, through the arrangement of the cooling box, when the cooling box is used, the lower die can be immediately moved into the cooling box after injection molding to carry out rapid cooling, the power supply of the fan motor and the micro water pump is turned on, cooling water cooled by the cooling fins in the cooling water box is guided into the multi-way pipe in the lower die through the hose, the multi-way pipe divides the cooling water into the transverse water-cooling pipe and the longitudinal water-cooling pipe, the die frame body is cooled through the transverse water-cooling pipe and the longitudinal water-cooling pipe, and multi-directional water cooling can be realized, so that the overall temperature of the lower die can be suddenly reduced, the cooling effect is improved, the overall shape of the foaming material can be kept stable, the injection molding quality is improved, the structure is.

2. According to the invention, through the arrangement of the air-cooled radiator, the cooling fan sucks the heat emitted from the surface of the lower die out of the cooling box to radiate the whole lower die, and the heat can be further discharged from the inside of the cooling box by matching with the cooling water tanks on two sides, so that the cooling efficiency is improved, and the working effect is better.

Drawings

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

FIG. 2 is an internal structural view of the present invention;

FIG. 3 is a cross-sectional view of the lower mold of the present invention;

FIG. 4 is an internal structural view of a cooling box of the present invention;

fig. 5 is an internal structure view of the air-cooled radiator of the present invention.

In the figure: 1. a base; 2. a cooling tank; 3. connecting a water pipe; 4. a vent hole; 5. mounting a plate; 6. fixing the sleeve plate; 7. a lower die; 8. an upper die; 9. injection molding holes; 10. limiting a guide rail; 11. a fixing plate; 12. a thimble; 13. a first electric cylinder; 14. installing a box; 15. fixing the sleeve; 16. a cooling box body; 17. an air-cooled radiator; 18. a second electric cylinder; 19. a vent; 20. connecting the pipe body; 21. an air suction opening; 22. a mold frame body; 23. injection molding a groove; 24. a multi-pass tube; 25. a transverse water-cooled tube; 26. a longitudinal water-cooled tube; 27. a cooling water tank; 28. a micro water pump; 29. a cooling fin; 30. a fan motor; 31. a cooling fan; 32. and (5) filtering by using a filter screen.

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 cooling device for injection molding of a foaming material comprises a cooling box 2, a lower die 7 and an upper die 8, wherein cooling box bodies 16 are arranged on two sides of the inside of the cooling box 2, an air-cooled radiator 17 is arranged below the space between the two cooling box bodies 16, the lower die 7 is positioned inside the cooling box 2, a cooling water tank 27 is arranged inside the cooling box body 16, hoses are arranged on two sides of the lower die 7 and extend into the cooling box bodies 16 to be hermetically connected with the cooling water tank 27, a die frame body 22 is arranged above the inside of the lower die 7, an injection molding groove 23 is arranged inside the die frame body 22, transverse water cooling pipes 25 are arranged below the inside of the die frame body 22, longitudinal water cooling pipes 26 are arranged on two sides of the inside of the die frame body 22, multi-way pipes 24 are arranged at two ends of the longitudinal water cooling pipes 26 and the transverse water cooling pipes 25, the multi-way pipes 24 are hermetically connected with the hoses, and the lower die 7 is immediately, carry out rapid cooling, through the power of opening fan motor 30 and micro-water pump 28, pass through the inside multi-ported tube 24 that receives cooling fin 29 cooling of coolant tank 27 in the leading-in bed die 7 inside of hose, multi-ported tube 24 will cool off water shunt to horizontal water-cooled tube 25 and vertical water-cooled tube 26, cool down to die frame body 22 through horizontal water-cooled tube 25 and vertical water-cooled tube 26, diversified water-cooling, can make the whole temperature dip of bed die 7, and the cooling effect is improved.

Further, mounting panel 5 is installed to the up end of cooler bin 2, mounting panel 5 is connected with cooler bin 2 through the fixed screw, fixed lagging 6 is installed to the top of mounting panel 5, fixed lagging 6 and 5 welded connection of mounting panel, the inside of fixed lagging 6 is provided with the opening, and the shape of opening is the same with the shape of bed die 7 and last mould 8 respectively, the lower extreme of cooler bin 2 is provided with base 1, can keep the stability that bed die 7 and last mould 8 removed the process through fixed lagging 6, and convenient to use.

Further, the outside of bed die 7 and last mould 8 is provided with limit guide rail 10, limit guide rail 10 sets up structure as an organic whole with bed die 7 and last mould 8, and bed die 7 and last mould 8 all through limit guide rail 10 and fixed sleeve plate 6 sliding connection, and the electronic jar 18 of second is all installed to the lower extreme both sides of bed die 7, the both ends of the electronic jar 18 of second respectively with bed die 7 and base 1 fixed connection, the removal of bed die 7 is controlled through the electronic jar 18 of second, so that cooling work.

Further, ejector pins 12 are installed at the upper end of the upper die 8, fixing plates 11 are installed above the ejector pins 12, the fixing plates 11 are fixedly connected with the ejector pins 12, the ejector pins 12 penetrate through the upper die 8 and are slidably connected with the upper die 8, first electric cylinders 13 are installed at the centers of the upper ends of the upper die 8, fixing sleeves 15 are installed at the lower ends of the first electric cylinders 13, the fixing sleeves 15 are connected with the upper die 8 through fixing screws, the upper ends of the first electric cylinders 13 are fixedly connected with the fixing plates 11, installation boxes 14 are installed above the fixing plates 11, the upper die 8 can be lifted through the first electric cylinders 13, and the cooled and formed foaming materials are taken out.

Further, the outside of going up mould 8 is provided with injection molding hole 9, injection molding hole 9 link up mould 8 and injection molding groove 23 intercommunication, injection molding groove 23 sets up structure as an organic whole with mould framework 22, and mould framework 22 sets up structure as an organic whole with bed die 7, horizontal water-cooled tube 25 and vertical water-cooled tube 26 all are provided with a plurality of, and the equal embedding mould framework 22 inside and mould framework 22 fixed connection of one end of horizontal water-cooled tube 25 of a plurality of and vertical water-cooled tube 26, cool down mould framework 22 through horizontal water-cooled tube 25 and vertical water-cooled tube 26, diversified water-cooling, can make 7 whole temperature of bed die suddenly drop, improve the cooling effect, and can keep the whole shape stability of expanded material, thereby improve injection-moulded's quality, moreover, the steam generator is simple in structure, and convenient for operation.

Further, the internally mounted of coolant tank 27 has miniature pump 28, miniature pump 28 and coolant tank 27 fixed connection, and miniature pump 28 and hose sealing connection, cooling fin 29 is installed to miniature pump 28's below, connecting pipe 3 is all installed to the both sides of coolant tank 2, connecting pipe 3 and coolant tank 27 sealing connection, install connecting pipe body 20 between two coolant tank 27, connecting pipe body 20 runs through inside and air-cooled radiator 17 fixed connection of air-cooled radiator 17, cooling fan 31 is outside with 2 outer with the heat suction coolant tanks of the lower mould 7 surface gived off, dispel the heat to lower mould 7 whole, can cooperate the coolant tank 27 of both sides, further discharge the heat from 2 inside of coolant tank, and the cooling efficiency is improved, and the work effect is better.

Further, the outer surface of the air-cooled radiator 17 is provided with a vent 19, the outer surface of the cooling box 2 is provided with a vent 4, the vent 4 is communicated with the vent 19, the air-cooled radiator 17 comprises a fan motor 30, a cooling fan 31 and a filter screen 32, the filter screen 32 is positioned at the upper end of the inside of the air-cooled radiator 17, an air suction opening 21 is installed at the upper end of the filter screen 32, the position of the air suction opening 21 corresponds to the position of the lower die 7, and heat inside the cooling box 2 is sucked out of the inside of the cooling box 2 through the air suction opening 21.

A use method of a cooling device for foam material injection molding comprises the following steps:

the method comprises the following steps: extending the first electric cylinder 13 to enable the upper die 8 and the lower die 7 to be closely attached, and performing injection molding on the foaming material through the injection molding hole 9;

step two: after injection molding, the second electric cylinder 18 is contracted to drive the lower mold 7 to move to the inside of the cooling tank 2, the power supply of the fan motor 30 and the micro water pump 28 is turned on, cooling water cooled by the cooling fins 29 in the cooling tank 27 is guided into the multi-way pipe 24 in the lower mold 7 through a hose, the multi-way pipe 24 divides the cooling water into the transverse water-cooling pipe 25 and the longitudinal water-cooling pipe 26, and the mold frame 22 is cooled through the transverse water-cooling pipe 25 and the longitudinal water-cooling pipe 26;

step three: the cooling fan 31 sucks the heat emitted from the surface of the lower mold 7 out of the cooling box 2 to dissipate the heat of the whole lower mold 7;

step four: after the heat dissipation, promote lower mould 7 with the electronic jar 18 of second, behind the fixed lagging 6 of lower mould 7 and the 8 roll-off of last mould, shrink first electronic jar 13, take out fashioned expanded material, remove through control lower mould 7 and last mould 8, can cool off the expanded material of inside design fast, the operation of being convenient for.

The working principle is as follows: when in use, the first electric cylinder 13 is extended to enable the upper die 8 and the lower die 7 to be closely attached, the foaming material injection molding work is carried out through the injection molding hole 9, after the molding, the second electric cylinder 18 is contracted to drive the lower die 7 to move to the inside of the cooling box 2, the power supply of the fan motor 30 and the micro water pump 28 is turned on, the cooling water cooled by the cooling fins 29 in the cooling water box 27 is guided into the multi-way pipe 24 in the lower die 7 through the hose, the multi-way pipe 24 divides the cooling water into the transverse water-cooling pipe 25 and the longitudinal water-cooling pipe 26, the die frame body 22 is cooled through the transverse water-cooling pipe 25 and the longitudinal water-cooling pipe 26, the multi-directional water-cooling is realized, the overall temperature of the lower die 7 can be suddenly reduced, the cooling effect is improved, the overall shape of the foaming material can be kept stable, the injection molding quality is improved, the structure is simple, the operation is convenient, the cooling fan 31 sucks, wholly dispel the heat to bed die 7, through inlet scoop 21 with 2 inside heat suction cooling boxs of cooling box 2 inside, after the heat dissipation, promote bed die 7 with the electronic jar 18 of second, after bed die 7 and the fixed lagging 6 of 8 roll-off of last mould, shrink first electronic jar 13, take out fashioned expanded material, remove through controlling bed die 7 and last mould 8, can cool off the cooling to the expanded material of inside design fast, the operation of being convenient for.

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.