阅读说明：本技术 一种自动化真空包装机 (Automatic change vacuum packaging machine ) 是由 杨海波 于 2021-08-24 设计创作，主要内容包括：本发明公开了一种自动化真空包装机,包括机座和机体,所述机体固定安装在所述机座顶部的中间位置处,所述机体的一侧开设有进口,所述机体的另一侧开设有出口,所述机体的表面安装有透明玻璃窗,所述机座顶部的两侧均固定安装有侧板,两块所述侧板之间活动安装有螺纹转轴,且所述螺纹转轴通过所述进口和所述出口贯穿所述机体,所述螺纹转轴上螺纹套接安装有内螺纹套,所述内螺纹套的顶部固定安装有下放置槽,所述机体内侧顶部的中间位置处固定安装有主气缸,所述主气缸的输出端设置有第一气动伸缩杆。本发明通过设置一系列的结构使得本装置在实际使用的过程中具有抽真空效果好效率高和便于移动以及移动后稳定性强的特点。(The invention discloses an automatic vacuum packaging machine which comprises a machine base and a machine body, wherein the machine body is fixedly arranged at the middle position of the top of the machine base, an inlet is formed in one side of the machine body, an outlet is formed in the other side of the machine body, a transparent glass window is arranged on the surface of the machine body, side plates are fixedly arranged on two sides of the top of the machine base, a threaded rotating shaft is movably arranged between the two side plates and penetrates through the machine body through the inlet and the outlet, an internal thread sleeve is sleeved on the threaded rotating shaft in a threaded manner, a lower placing groove is fixedly arranged at the top of the internal thread sleeve, a main air cylinder is fixedly arranged at the middle position of the top of the inner side of the machine body, and a first pneumatic telescopic rod is arranged at the output end of the main air cylinder. The vacuum pumping device has the characteristics of good vacuum pumping effect, high efficiency, convenience in movement and strong stability after movement in the actual use process by arranging a series of structures.)

1. The utility model provides an automatic change vacuum packaging machine, includes frame (1) and organism (2), its characterized in that: the machine body (2) is fixedly arranged in the middle of the top of the machine base (1), an inlet (21) is formed in one side of the machine body (2), an outlet (28) is formed in the other side of the machine body (2), a transparent glass window (3) is arranged on the surface of the machine body (2), side plates (9) are fixedly arranged on two sides of the top of the machine base (1), a threaded rotating shaft (8) is movably arranged between the two side plates (9), the threaded rotating shaft (8) penetrates through the machine body (2) through the inlet (21) and the outlet (28), an internal threaded sleeve (19) is sleeved on the threaded rotating shaft (8) in a threaded manner, a lower placing groove (20) is fixedly arranged at the top of the internal threaded sleeve (19), a main air cylinder (25) is fixedly arranged in the middle of the top of the inner side of the machine body (2), and a first pneumatic telescopic rod (26) is arranged at the output end of the main air cylinder (25), an upper pressure groove (27) is fixedly installed at the bottom end of the first pneumatic telescopic rod (26), a vacuumizing machine (5) is fixedly installed at the middle position of the top of the machine body (2), an exhaust pipe (4) is arranged on one side of the vacuumizing machine (5), an air suction pipe (6) is arranged on the other side of the vacuumizing machine (5), one end of the air suction pipe (6) extends into the machine body (2), a corrugated hose (41) is connected to one end, located inside the machine body (2), of the air suction pipe (6), a sealing pipe sleeve (47) is arranged at the top of the upper pressure groove (27), an air inlet pipe (46) is fixedly installed at the top of the upper pressure groove (27) through the sealing pipe sleeve (47), one end of the air inlet pipe (46) is located on the inner side of the upper pressure groove (27), and the other end of the air inlet pipe (46) is connected with the corrugated hose (41), the mounting groove (30) is formed in the base (1), the mounting groove (30) is of a bottom opening structure, a sliding rod (29) is fixedly mounted at the top of the inner side of the mounting groove (30), a sliding sleeve (16) is movably sleeved on the sliding rod (29), a first triangular block (15) is fixedly mounted at the bottom of the sliding sleeve (16), an electric push rod (48) is fixedly mounted above one side of the inner portion of the mounting groove (30), one end of the electric push rod (48) is fixedly connected with the first triangular block (15), sliding grooves (54) are formed in two sides of the inner portion of the mounting groove (30), two sliding rails (52) are fixedly mounted in the inner portion of each sliding groove (54), sliding blocks (53) are movably mounted on the four sliding rails (52), a lifting plate (49) is fixedly mounted between the four sliding blocks (53), and a third spring (51) is sleeved on each sliding rail (52), third spring (51) are located under slider (53), the intermediate position department at lifter plate (49) top is provided with three hornblocks of second (31), four equal fixed mounting in end of lifter plate (49) bottom have stand (50), the bottom of lifter plate (49) is through four stand (50) fixed mounting has pressure-bearing plate (12).

2. The automated vacuum packaging machine of claim 1, wherein: go up one side fixed mounting at indent (27) inboard top has thumb cylinder (42), the output of thumb cylinder (42) is provided with second pneumatic telescopic link (43), the bottom fixed mounting of second pneumatic telescopic link (43) has mounting panel (44), the bottom fixed mounting of mounting panel (44) has last hot sealing rod (45), one side fixed mounting of putting down groove (20) inboard bottom has down to hold joint block (40).

3. The automated vacuum packaging machine of claim 1, wherein: sealing strips (36) are fixedly bonded at the edge of the bottom of the upper pressure groove (27) and the edge of the top of the lower placing groove (20).

4. The automated vacuum packaging machine of claim 1, wherein: two fixed mounting has gag lever post (7) between curb plate (9), gag lever post (7) are located under screw thread pivot (8), movable sleeve joint is gone up in gag lever post (7) installs stop collar (17), stop collar (17) with be provided with connecting block (18) between internal thread bush (19), stop collar (17) with pass through between internal thread bush (19) connecting block (18) fixed connection, and wherein one side fixed mounting of curb plate (9) has driving motor (10), the one end of screw thread pivot (8) with the output fixed connection of driving motor (10).

5. The automated vacuum packaging machine of claim 1, wherein: four ends of the bottom of the machine base (1) are respectively provided with a wheel carrier (14), and the inner sides of the four wheel carriers (14) are respectively and movably provided with a movable wheel (11).

6. The automated vacuum packaging machine of claim 1, wherein: go up indent (27) inboard top and install two extensible member (23), two clamp plate (24) are installed to the bottom of extensible member (23), and two all the cover is equipped with first spring (22) on extensible member (23).

7. The automated vacuum packaging machine of claim 1, wherein: be provided with two swing joint spare (35) on the lateral wall of inferior placement groove (20) inside one side, there are two connecting rods (38), two through two swing joint spare (35) movable mounting in inferior placement groove (20) inside one side the one end of connecting rod (38) all is provided with depression bar (39), and the bottom of two depression bars (39) all is provided with briquetting (33), two the bottom of briquetting (33) all is provided with rubber pad (32), and two the equal fixedly connected with second spring (34) in one side of connecting rod (38), the one end of two second spring (34) all with the inner wall fixed connection of inferior placement groove (20), two the other end of connecting rod (38) all is provided with pull ring (37).

8. The automated vacuum packaging machine of claim 1, wherein: wear-resisting non-slip mat (13) is installed to the bottom of pressure-bearing plate (12), wear-resisting non-slip mat (13) with it is fixed to bond through powerful glue between pressure-bearing plate (12).

Technical Field

The invention relates to the technical field of vacuum packaging machines, in particular to an automatic vacuum packaging machine.

Background

The vacuum packaging machine can automatically pump out air in the packaging bag, complete the sealing process after reaching a preset vacuum degree, and can also be refilled with nitrogen or other mixed gas to complete the sealing process.

The existing vacuum packaging machine is single in structure, when the product is vacuumized and sealed, the product is easy to displace, and further the ideal vacuumizing effect cannot be achieved, the vacuumizing is long in time consumption, the packaging efficiency is influenced, the flexibility of the device is enhanced, the product can be generally installed and moved at the bottom of a vacuum packaging machine body, but the stability of the packaging machine is reduced, the displacement of the vacuum packaging machine is easy to occur, the vacuum packaging machine is inconvenient to use by workers, the practicability of the vacuum packaging machine is reduced, and therefore, the problem of solving the automatic vacuum packaging machine is solved for solving the series of problems.

Disclosure of Invention

The present invention is directed to an automated vacuum packaging machine, which solves the above problems of the prior art.

In order to achieve the purpose, the invention provides the following technical scheme: an automatic vacuum packaging machine comprises a machine base and a machine body, wherein the machine body is fixedly arranged at the middle position of the top of the machine base, one side of the machine body is provided with an inlet, the other side of the machine body is provided with an outlet, the surface of the machine body is provided with a transparent glass window, both sides of the top of the machine base are fixedly provided with side plates, a threaded rotating shaft is movably arranged between the two side plates and penetrates through the machine body through the inlet and the outlet, an internal thread sleeve is sleeved on the threaded rotating shaft in a threaded manner, the top of the internal thread sleeve is fixedly provided with a lower placing groove, a main air cylinder is fixedly arranged at the middle position of the top of the inner side of the machine body, the output end of the main air cylinder is provided with a first pneumatic telescopic rod, the bottom end of the first pneumatic telescopic rod is fixedly provided with an upper pressure groove, and a vacuum extractor is fixedly arranged at the middle position of the top of the machine body, an exhaust pipe is arranged on one side of the vacuum extractor, an air suction pipe is arranged on the other side of the vacuum extractor, one end of the air suction pipe extends into the vacuum extractor, one end of the air suction pipe, which is positioned in the vacuum extractor, is connected with a corrugated hose, a sealing pipe sleeve is arranged on the top of the upper pressure groove, an air inlet pipe is fixedly arranged on the top of the upper pressure groove through the sealing pipe sleeve, one end of the air inlet pipe is positioned in the upper pressure groove, the other end of the air inlet pipe is connected with the corrugated hose, a mounting groove is formed in the base, the mounting groove is of a bottom opening structure, a slide rod is fixedly arranged on the top of the inner side of the mounting groove, a slide sleeve is movably sleeved on the slide rod, a first triangular block is fixedly arranged at the bottom of the slide sleeve, an electric push rod is fixedly arranged above one side of the inner part of the mounting groove, and one end of the electric push rod is fixedly connected with the first triangular block, the inside both sides of mounting groove have all been seted up the spout, two the equal fixed mounting in inside of spout has two slide rails, and equal movable mounting has the slider on four slide rails, and fixed mounting has the lifter plate, four between four sliders all the cover is equipped with the third spring on the slide rail, the third spring is located under the slider, the intermediate position department at lifter plate top is provided with three hornblocks of second, the equal fixed mounting in four ends of lifter plate bottom has the stand, four are passed through to the bottom of lifter plate stand fixed mounting has the bearing plate.

Preferably, go up one side fixed mounting at indent inboard top has the thumb cylinder, the output of thumb cylinder is provided with the pneumatic telescopic link of second, the bottom fixed mounting of the pneumatic telescopic link of second has the mounting panel, the bottom fixed mounting of mounting panel has last heat seal pole, one side fixed mounting who places the inslot side bottom down has the lower piece that holds.

Preferably, sealing strips are fixedly bonded at the edge of the bottom of the upper pressure tank and the edge of the top of the lower placing tank.

Preferably, two fixed mounting has the gag lever post between the curb plate, the gag lever post is located under the screw thread pivot, the movable sleeve joint is installed with the stop collar on the gag lever post, the stop collar with be provided with the connecting block between the interior thread bush, the stop collar with pass through between the interior thread bush connecting block fixed connection, and one of them one side fixed mounting of curb plate has driving motor, the one end of screw thread pivot with driving motor's output fixed connection.

Preferably, four ends of the bottom of the machine base are respectively provided with a wheel carrier, and the inner sides of the four wheel carriers are respectively and movably provided with a movable wheel.

Preferably, two telescopic parts are installed at the top of the inner side of the upper pressure groove, two pressure plates are installed at the bottom ends of the telescopic parts, and two first springs are sleeved on the telescopic parts.

Preferably, be provided with two swing joint spare on the lateral wall of inferior placement inslot portion one side, there are two connecting rods, two through two swing joint spare movable mounting in one side of inferior placement inslot portion the one end of connecting rod all is provided with the depression bar, and the bottom of two depression bars all is provided with the briquetting, two the bottom of briquetting all is provided with the rubber pad, and two the equal fixedly connected with second spring in one side of connecting rod, the one end of two second springs all with the inner wall fixed connection in inferior placement groove, two the other end of connecting rod all is provided with the pull ring.

Preferably, the bottom of the pressure bearing plate is provided with a wear-resistant non-slip mat, and the wear-resistant non-slip mat is fixedly bonded with the pressure bearing plate through super glue.

Compared with the prior art, the invention has the beneficial effects that: the invention has scientific and reasonable structure and safe and convenient use:

the driving motor is controlled to drive the threaded rotating shaft to rotate, the threaded rotating shaft drives the internal thread sleeve to move back and forth, and then the internal thread sleeve drives the lower placing groove to move;

the main cylinder is controlled, so that the main cylinder drives the first pneumatic telescopic rod to extend out, the first pneumatic telescopic rod drives the upper pressure groove to move downwards to be combined with the lower placing groove, the pressing plate extrudes the telescopic piece when the upper pressure groove moves downwards, the packaging bag can be tightly pressed under the action of the first spring, and meanwhile, when the packaging bag is placed into the lower placing groove, the two pull rings are respectively pulled upwards, so that the pressing rod moves downwards under the action of the second spring, and the two ends of one side to be sealed of the packaging bag are tightly pressed through the pressing block, so that the packaging bag can be effectively prevented from generating displacement during vacuumizing and sealing, and the vacuumizing and sealing effects are influenced;

make this device be convenient for remove through removing the wheel, when removing the assigned position and need using, control electric putter, make electric putter promote first triangle piece and remove, when first triangle piece removes to the three triangle piece tops of second, make the lifter plate move down certain distance through the effect of three triangle pieces of first triangle piece and second, and then can make bearing plate and ground contact, support this device, improve the stability of this device, make this device on the basis of being convenient for remove, stability is still strong during the use.

Drawings

FIG. 1 is a front view of the present invention;

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

FIG. 3 is an enlarged view of the invention at A in FIG. 2;

FIG. 4 is an enlarged view of the invention at B in FIG. 2;

fig. 5 is an enlarged view of the invention at C in fig. 2.

In the figure: 1. a machine base; 2. a body; 3. a transparent glass window; 4. an exhaust pipe; 5. a vacuum extractor; 6. an air intake duct; 7. a limiting rod; 8. a threaded shaft; 9. a side plate; 10. a drive motor; 11. a moving wheel; 12. a pressure bearing plate; 13. a wear-resistant anti-slip pad; 14. a wheel carrier; 15. a first triangular block; 16. a sliding sleeve; 17. a limiting sleeve; 18. connecting blocks; 19. an internal thread sleeve; 20. placing the tank down; 21. an inlet; 22. a first spring; 23. a telescoping member; 24. pressing a plate; 25. a master cylinder; 26. a first pneumatic telescopic rod; 27. pressing the groove upwards; 28. an outlet; 29. a slide bar; 30. mounting grooves; 31. a second triangular block; 32. a rubber pad; 33. briquetting; 34. a second spring; 35. a movable connecting piece; 36. a sealing strip; 37. a pull ring; 38. a connecting rod; 39. a pressure lever; 40. a lower bearing block; 41. a corrugated hose; 42. a thumb cylinder; 43. a second pneumatic telescopic rod; 44. mounting a plate; 45. an upper heat seal rod; 46. an air inlet pipe; 47. sealing the pipe sleeve; 48. an electric push rod; 49. a lifting plate; 50. a column; 51. a third spring; 52. a slide rail; 53. a slider; 54. a chute.

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. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-5, the present invention provides a technical solution: an automatic vacuum packaging machine technical scheme comprises a machine base 1 and a machine body 2, the machine body 2 is fixedly arranged at the middle position of the top of the machine base 1, one side of the machine body 2 is provided with an inlet 21, the other side of the machine body 2 is provided with an outlet 28, the surface of the machine body 2 is provided with a transparent glass window 3, two sides of the top of the machine base 1 are both fixedly provided with side plates 9, a threaded rotating shaft 8 is movably arranged between the two side plates 9, the threaded rotating shaft 8 penetrates through the machine body 2 through the inlet 21 and the outlet 28, an internal thread sleeve 19 is sleeved on the threaded rotating shaft 8, a lower placing groove 20 is fixedly arranged at the top of the internal thread sleeve 19, a main air cylinder 25 is fixedly arranged at the middle position of the top of the inner side of the machine body 2, the output end of the main air cylinder 25 is provided with a first pneumatic telescopic rod 26, the bottom end of the first pneumatic telescopic rod 26 is fixedly provided with an upper pressure groove 27, and a vacuum extractor 5 is fixedly arranged at the middle position of the top of the machine body 2, an exhaust pipe 4 is arranged on one side of a vacuum extractor 5, an air suction pipe 6 is arranged on the other side of the vacuum extractor 5, one end of the air suction pipe 6 extends into an engine body 2, one end of the air suction pipe 6, which is positioned inside the engine body 2, is connected with a corrugated hose 41, a sealing pipe sleeve 47 is arranged on the top of an upper pressure groove 27, an air inlet pipe 46 is fixedly arranged on the top of the upper pressure groove 27 through the sealing pipe sleeve 47, one end of the air inlet pipe 46 is positioned inside the upper pressure groove 27, the other end of the air inlet pipe 46 is connected with the corrugated hose 41, an installation groove 30 is arranged inside the engine base 1, the installation groove 30 is of a bottom opening structure, a slide bar 29 is fixedly arranged on the top of the inner side of the installation groove 30, a slide sleeve 16 is movably sleeved on the slide bar 29, a first triangular block 15 is fixedly arranged on the bottom of the slide sleeve 16, an electric push rod 48 is fixedly arranged above one side of the inner part of the installation groove 30, one end of the electric push rod 48 is fixedly connected with the first triangular block 15, spout 54 has all been seted up to the inside both sides of mounting groove 30, two equal fixed mounting in inside of spout 54 has two slide rails 52, equal movable mounting has slider 53 on four slide rails 52, fixed mounting has lifter plate 49 between four slider 53, all the cover is equipped with third spring 51 on four slide rails 52, third spring 51 is located slider 53 under, the intermediate position department at lifter plate 49 top is provided with three hornblocks 31 of second, the equal fixed mounting in four ends of lifter plate 49 bottom has stand 50, lifter plate 49's bottom has bearing plate 12 through four stand 50 fixed mounting.

Preferably, one side fixed mounting at the inboard top of last indent 27 has thumb cylinder 42, the output of thumb cylinder 42 is provided with second pneumatic telescopic link 43, the bottom fixed mounting of second pneumatic telescopic link 43 has mounting panel 44, the bottom fixed mounting of mounting panel 44 has last heat seal pole 45, one side fixed mounting of the inboard bottom of lower holding tank 20 has lower supporting block 40, control thumb cylinder 42, make it drive second pneumatic telescopic link 43 stretch out, and then drive mounting panel 44 and move down, make it move down and contact with lower supporting block 40 to go up heat seal pole 45, seal the processing to the wrapping bag.

Preferably, the edge of the bottom of the upper pressure groove 27 and the edge of the top of the lower placing groove 20 are fixedly bonded with the sealing strip 36, so that the sealing performance of the upper pressure groove 27 combined with the lower placing groove 20 is good, and the outside air cannot enter during vacuumizing.

Preferably, fixed mounting has gag lever post 7 between two blocks of curb plates 9, gag lever post 7 is located screw thread pivot 8 under, movable sleeve joint installs stop collar 17 on the gag lever post 7, be provided with connecting block 18 between stop collar 17 and the internal thread cover 19, through connecting block 18 fixed connection between stop collar 17 and the internal thread cover 19, when making screw thread pivot 8 rotate, internal thread cover 19 can not rotate along with screw thread pivot 8's rotation, can only be on screw thread pivot 8 back-and-forth movement, and one side fixed mounting of one of them curb plate 9 has driving motor 10, screw thread pivot 8's one end and driving motor 10's output fixed connection, and then be convenient for drive screw thread pivot 8 rotates.

Preferably, four ends of the bottom of the machine base 1 are respectively provided with a wheel carrier 14, and the inner sides of the four wheel carriers 14 are respectively and movably provided with a movable wheel 11, so that the device is reasonable in design and convenient to move.

Preferably, two telescopic parts 23 are installed at the top of the inner side of the upper pressure groove 27, the pressing plates 24 are installed at the bottom ends of the two telescopic parts 23, the first springs 22 are sleeved on the two telescopic parts 23, when the upper pressure groove 27 moves downwards, the pressing plates 24 extrude the telescopic parts 23, and the packaging bag can be pressed tightly under the action of the first springs 22.

Preferably, be provided with two swing joint 35 on the lateral wall of the inside one side of lower placement groove 20, there are two connecting rods 38 in the inside one side of lower placement groove 20 through two swing joint 35 movable mounting, the one end of two connecting rods 38 all is provided with depression bar 39, the bottom of two depression bars 39 all is provided with briquetting 33, the bottom of two briquetting 33 all is provided with rubber pad 32, and the equal fixedly connected with second spring 34 in one side of two connecting rods 38, the one end of two second springs 34 all with the inner wall fixed connection of lower placement groove 20, the other end of two connecting rods 38 all is provided with pull ring 37, upwards stimulate two pull ring 37 respectively, make depression bar 39 push down through the effect of second spring 34, compress tightly the wrapping bag through briquetting 33 and wait to seal the both ends of one side.

Preferably, the bottom of the pressure bearing plate 12 is provided with a wear-resistant anti-slip pad 13, and the wear-resistant anti-slip pad 13 is bonded and fixed with the pressure bearing plate 12 through strong glue, so that the friction force between the pressure bearing plate 12 and the ground is improved, and the stability of the device is enhanced.

The working principle is as follows: before use, the safety of each structure of the device is checked, the device is moved to a specified use position through the moving wheel 11, then the electric push rod 48 is controlled, the electric push rod 48 pushes the first triangular block 15 to move, when the first triangular block 15 moves to the top of the second triangular block 31, the lifting plate 49 moves downwards for a certain distance through the action of the first triangular block 15 and the second triangular block 31, the bearing plate 12 can be contacted with the ground to support the device, the driving motor 10 is controlled, the driving motor 10 can drive the threaded rotating shaft 8 to rotate, the threaded rotating shaft 8 drives the internal threaded sleeve 19 to move back and forth, the lower placing groove 20 moves out of the machine body, products are placed into the packaging bag, the packaging bag is placed into the lower placing groove 20, when the packaging bag is placed into the lower placing groove 20, the two pull rings 37 are respectively pulled upwards, so that the press rod 39 is pressed downwards through the action of the second spring 34, the two ends of one side to be sealed of the packaging bag are pressed through the pressing block 33, the driving motor 10 is controlled, the lower placing groove 20 is moved to the inside of the machine body 2 and is positioned under the upper pressure groove 27, the main cylinder 25 is controlled, the main cylinder 25 can drive the first pneumatic telescopic rod 26 to extend out, the first pneumatic telescopic rod 26 drives the upper pressure groove 27 to move downwards to be combined with the lower placing groove 20, when the upper pressure groove 27 moves downwards, the pressing plate 24 extrudes the telescopic piece 23, the packaging bag can be pressed through the action of the first spring 22, the vacuumizing machine 5 is controlled, the vacuumizing machine 5 can vacuumize the insides of the upper pressure groove 27 and the lower placing groove 20, after vacuumizing, the thumb cylinder 42 is controlled again to drive the second pneumatic telescopic rod 43 to extend out, the mounting plate 44 is driven to move downwards, the upper heat sealing rod 45 moves downwards to be contacted with the lower bearing block 40, the packaging bag is sealed, the upper pressure groove 27 is moved upwards, the driving motor 10 is controlled, the lower placing groove 20 is moved out of the machine body 2, and the processed packaged product can be taken out.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.