阅读说明：本技术 一种五金板料自动夹持移动机构 (Automatic clamping and moving mechanism for hardware plates ) 是由 陈永珊 潘世贝 于 2020-08-18 设计创作，主要内容包括：本发明公开了一种五金板料自动夹持移动机构,包括工作台,所述工作台的两侧设有对称分布的两组放置板,所述放置板靠近工作台的一侧设有对称分布的两组第一滑轴,所述工作台的下侧设有U型支撑板,所述U型支撑板的一侧设有伺服电机,所述U型支撑板靠近伺服电机的一侧通过六角螺栓连接有环形固定板,所述U型支撑板远离伺服电机的一侧设有PLC控制器,所述伺服电机的输出轴通过联轴器连接有转动轴的一端,所述转动轴的另一端穿过U型支撑板并连接有丝杠,通过工作台两侧设有的放置板可以放置储放五金板料,对五金板料夹持移动时,可以直接从放置板上推动到支撑转筒的上侧,从而便于工作人员操作,快速方便。(The invention discloses an automatic hardware plate clamping and moving mechanism, which comprises a workbench, wherein two groups of symmetrically distributed placing plates are arranged on two sides of the workbench, two groups of symmetrically distributed first sliding shafts are arranged on one side, close to the workbench, of the placing plates, a U-shaped supporting plate is arranged on the lower side of the workbench, a servo motor is arranged on one side of the U-shaped supporting plate, one side, close to the servo motor, of the U-shaped supporting plate is connected with an annular fixing plate through a hexagon bolt, a PLC (programmable logic controller) is arranged on one side, far away from the servo motor, of the U-shaped supporting plate, an output shaft of the servo motor is connected with one end of a rotating shaft through a coupling, the other end of the rotating shaft penetrates through the U-shaped supporting plate and is connected with a lead screw, hardware plates can be placed and stored through the placing plates arranged on two sides of the workbench, thereby being convenient for the staff to operate, quick and convenient.)

1. The utility model provides an automatic centre gripping moving mechanism of five metals sheet material, includes workstation (1), its characterized in that: two groups of symmetrically distributed placing plates (19) are arranged on two sides of the workbench (1), two groups of symmetrically distributed first sliding shafts (4) are arranged on one side, close to the workbench (1), of each placing plate (19), a U-shaped supporting plate (25) is arranged on the lower side of the workbench (1), a servo motor (18) is arranged on one side of each U-shaped supporting plate (25), one side, close to the servo motor (18), of each U-shaped supporting plate (25) is connected with an annular fixing plate (17) through a hexagonal bolt, a PLC (programmable logic controller) (27) is arranged on one side, far away from the servo motor (18), of each U-shaped supporting plate (25) is connected with one end of a rotating shaft through a coupler, the other end of the rotating shaft penetrates through the U-shaped supporting plate (25) and is connected with a lead screw (30), and the lead screw (30) is connected with the U-, the middle position of the lead screw (30) is in threaded connection with a guide post (31), two sides of the guide post (31) are connected with two sets of L-shaped connecting rods (29) which are symmetrically distributed, one end of the upper portion of each L-shaped connecting rod (29) is connected with a fixing plate (9), a first sliding shaft (4) is in sliding connection with a sliding hole (11) and a sliding hole (11) which are arranged at positions corresponding to the L-shaped connecting rods (29), column grooves (3) which are uniformly distributed at equal intervals are formed in the workbench (1), the middle positions of the column grooves (3) are connected with a first rotating shaft (8) through bearings, a supporting rotating cylinder (16) is arranged at the middle position of the outer side of the first rotating shaft (8), anti-slip layers are arranged on the outer sides of the supporting rotating cylinder (16), one end of the first rotating shaft (8) penetrates through the workbench (1) and is connected with a first gear (6), and a second rotating shaft (6) which is uniformly distributed at one side, close to the first gear (6) 15) The utility model discloses a hydraulic drive system, the outside intermediate position of second pivot (15) all is equipped with second gear (7), second gear (7) and first gear (6) meshing, one side intermediate position that workstation (1) was kept away from in fixed plate (9) all is equipped with pillar stand (2), one side intermediate position that pillar stand (2) are close to fixed plate (9) all is equipped with logical groove, the inside that leads to the groove all is equipped with first electric telescopic handle (10), the one end that pillar stand (2) were kept away from in first electric telescopic handle (10) all is connected with splint (12), the input of first electric telescopic handle (10) and servo motor (18) is connected to the output difference electricity of PLC controller (27).

2. The automatic clamping and moving mechanism for hardware plates as claimed in claim 1, is characterized in that: the downside equidistance symmetric distribution of U type backup pad (25) stands (22) more than six groups, the one end that U type backup pad (25) were kept away from in stand (22) is connected with mounting panel (24).

3. The automatic clamping and moving mechanism for hardware plates as claimed in claim 2, is characterized in that: the mounting panel (24) are connected with stand (22) through triangle fixed rib (23) more than four groups of equal angle symmetric distribution, the outside of mounting panel (24) is equipped with mounting hole (21) more than four groups of equal angle symmetric distribution.

4. The automatic clamping and moving mechanism for hardware plates as claimed in claim 1, is characterized in that: u type backup pad (25) are close to lower part one side intermediate position of PLC controller (27) and are equipped with double-shaft motor (20), one side that U type backup pad (25) are close to double-shaft motor (20) is equipped with the motor fixed plate, the input of double-shaft motor (20) is connected to the output electricity of PLC controller (27).

5. The automatic clamping and moving mechanism for hardware plates as claimed in claim 4, is characterized in that: the output shaft of the double-shaft motor (20) is connected with one end of a rotating shaft through a coupler, and the other end of the rotating shaft is connected with a V-shaped wheel (26).

6. The automatic clamping and moving mechanism for hardware plates as claimed in claim 1, is characterized in that: two groups of symmetrically distributed annular rotating grooves (5) are formed in one side, close to the V-shaped wheel (26), of the supporting rotating drum (16), and the annular rotating grooves (5) are connected with the V-shaped wheel (26) in a matched mode through a V-shaped belt (28).

7. The automatic clamping and moving mechanism for hardware plates as claimed in claim 1, is characterized in that: one side of the clamping plate (12) close to the supporting rotary drum (16) is provided with an arc through groove (34), and one side of the clamping plate (12) close to the arc through groove (34) is provided with more than four groups of bottom supporting plates (14) which are distributed at equal intervals.

8. The automatic clamping and moving mechanism for hardware plates as claimed in claim 1, is characterized in that: two sets of second sliding shafts (13) which are symmetrically distributed are connected between the fixing plates (9), and the second sliding shafts (13) are connected with the clamping plates (12) in a sliding mode through holes formed in the corresponding positions of the clamping plates (12).

9. The automatic clamping and moving mechanism for hardware plates as claimed in claim 1, is characterized in that: the upside intermediate position of splint (12) all is equipped with connecting plate (33), the intermediate position of connecting plate (33) all is equipped with second electric telescopic handle (32), the input of second electric telescopic handle (32) is connected to the output electricity of PLC controller (27).

10. The automatic clamping and moving mechanism for hardware plates as claimed in claim 9, is characterized in that: one end of the second electric telescopic rod (32) close to the workbench (1) is connected with a pressing plate (35), and one side of the pressing plate (35) close to the workbench (1) is provided with an anti-slip pad.

Technical Field

The invention relates to the technical field of clamping and moving mechanisms, in particular to an automatic hardware plate clamping and moving mechanism.

Background

The existing hardware plate such as a steel plate needs to be cut before being processed, the hardware plate needs to be clamped and fixed before being cut, but the existing clamping mechanism cannot move, needs to be manually pushed by workers, wastes time and labor, cannot realize quick and convenient position clamping and fixing of the hardware plate, and is inconvenient to use, for example, the patent of application publication No. 201721417912.4 discloses an automatic clamping and moving mechanism for the hardware plate, which comprises a frame, wherein a central through groove is formed in the middle of a top plate of the frame, an upper block body is fixed on the top surface of the top plate of the frame, a transverse through groove is formed in the middle of the upper block body, a transverse cutting through groove is formed in the top surface of the transverse through groove, an upper fixing groove body is fixed on the top surface of the upper block body, a plate to be cut is inserted and sleeved in a lower groove of the upper fixing groove body, and adjusting screws are arranged at the, but above patent is in the use, and unable shift position needs staff's manual promotion, wastes time and energy, can't realize carrying out quick convenient position to the five metals sheet material and step up fixedly, and it is inconvenient to use.

Therefore, the automatic hardware plate clamping and moving mechanism is provided.

Disclosure of Invention

The invention aims to overcome the existing defects and provides an automatic hardware plate clamping and moving mechanism which can quickly and conveniently move the position of a hardware plate, is time-saving and labor-saving, can quickly and conveniently clamp and fix the position of the hardware plate, is convenient to use and can effectively solve the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme: an automatic clamping and moving mechanism for hardware plates comprises a workbench, wherein two sets of placing plates are symmetrically arranged on two sides of the workbench, two sets of first sliding shafts are symmetrically arranged on one side, close to the workbench, of each placing plate, a U-shaped supporting plate is arranged on the lower side of the workbench, a servo motor is arranged on one side of each U-shaped supporting plate, an annular fixing plate is connected to one side, close to the servo motor, of each U-shaped supporting plate through a hexagon bolt, a PLC (programmable logic controller) is arranged on one side, away from the servo motor, of each U-shaped supporting plate, an output shaft of the servo motor is connected with one end of a rotating shaft through a coupler, the other end of the rotating shaft penetrates through the U-shaped supporting plate and is connected with a lead screw, the lead screw is connected with the U-shaped supporting plates through a bearing, a guide pillar, the upper end of the L-shaped connecting rod is connected with a fixed plate, the first sliding shaft is connected with the sliding holes through the sliding holes arranged at the corresponding positions of the L-shaped connecting rod in a sliding manner, column grooves with equal distance and uniform distribution are arranged in the workbench, the middle positions of the column grooves are connected with a first rotating shaft through bearings, the middle position of the outer side of the first rotating shaft is provided with a supporting rotating drum, the outer side of the supporting rotating drum is provided with an anti-skid layer, one end of the first rotating shaft penetrates through the workbench and is connected with a first gear, one side of the workbench, which is close to the first gear, is connected with a second rotating shaft with equal distance and uniform distribution through bearings, the middle position of the outer side of the second rotating shaft is provided with a second gear, the second gear is meshed with the first gear, the middle position of one side, which is far away from the workbench, of the fixed plate is provided with a column table, and, the inside in logical groove all is equipped with first electric telescopic handle, the one end that first electric telescopic handle kept away from the stylobate all is connected with splint, first electric telescopic handle and servo motor's input is connected to the output of PLC controller electricity respectively.

As a preferable technical scheme of the invention, more than six groups of upright columns are equidistantly and symmetrically distributed on the lower side of the U-shaped support plate, and one ends of the upright columns, which are far away from the U-shaped support plate, are connected with a mounting plate.

As a preferable technical scheme of the invention, the mounting plate is connected with the upright post through more than four groups of triangular fixing ribs which are distributed at equal angles symmetrically, and more than four groups of mounting holes which are distributed at equal angles symmetrically are arranged at the outer side of the mounting plate.

According to a preferable technical scheme of the invention, a double-shaft motor is arranged in the middle of one side of the lower part of the U-shaped supporting plate close to the PLC, a motor fixing plate is arranged on one side of the U-shaped supporting plate close to the double-shaft motor, and the output end of the PLC is electrically connected with the input end of the double-shaft motor.

As a preferable technical scheme of the present invention, output shafts of the dual-shaft motors are connected to one end of a rotating shaft through a coupling, and the other end of the rotating shaft is connected to a V-shaped wheel.

As a preferable technical scheme of the invention, two groups of symmetrically distributed annular rotating grooves are arranged on one side of the supporting rotating drum close to the V-shaped wheel, and the annular rotating grooves are connected with the V-shaped wheel in a matched manner through a V-shaped belt.

As a preferable technical scheme of the invention, the side of the clamping plate close to the supporting rotary drum is provided with an arc through groove, and the side of the clamping plate close to the arc through groove is provided with more than four groups of bottom supporting plates which are distributed at equal intervals.

As a preferable technical scheme of the invention, two groups of second sliding shafts which are symmetrically distributed are connected between the fixing plates, and the second sliding shafts are in sliding connection with the clamping plates through holes arranged at corresponding positions of the clamping plates.

According to a preferable technical scheme of the invention, the middle positions of the upper sides of the clamping plates are respectively provided with a connecting plate, the middle positions of the connecting plates are respectively provided with a second electric telescopic rod, and the output end of the PLC is electrically connected with the input end of the second electric telescopic rod.

As a preferable technical scheme, one end of the second electric telescopic rod, which is close to the workbench, is connected with a pressing plate, and one side of the pressing plate, which is close to the workbench, is provided with an anti-skid pad.

Compared with the prior art, the invention has the beneficial effects that: 1. the placing plates arranged on the two sides of the workbench can be used for placing and storing the hardware plates, and when the hardware plates are clamped and moved, the hardware plates can be directly pushed to the upper side of the supporting rotary drum from the placing plates, so that the operation of workers is convenient, and the operation is rapid and convenient;

2. two groups of output shafts of a double-shaft motor rotate to drive a V-shaped wheel to be matched with a V-shaped belt, an annular rotary groove and the like to drive one group of supporting rotary drums to rotate, and then the supporting rotary drums are driven to rotate by meshing of a first gear and a second gear, so that the positions of the hardware plates can be rapidly and labor-saving moved, the friction force during the movement of the hardware plates is greatly reduced, and the time and the labor are saved;

3. the clamping plates which are connected through telescopic pushing of the first electric telescopic rod move along the axis direction of the second sliding shaft, so that two sides of the hardware plate are clamped, the position of the hardware plate can be quickly adjusted, the hardware plate can be quickly clamped and fixed, and the hardware plate is clamped on the upper side of the workbench;

4. the pressing plate which is connected through the telescopic pushing of the second electric telescopic rod presses the hardware plate downwards, so that the lower side of the hardware plate is attached to the upper side of the bottom supporting plate, the upper side and the lower side of the hardware plate are fastened and fixed, the hardware plate is fastened and fixed in all directions by matching with the clamping plate, and the situation of shaking is prevented;

5. the output shaft of the servo motor rotates to drive the connected lead screw to rotate, the lead screw rotates to drive the guide pillar in threaded connection to move along the axis direction of the first sliding shaft, and therefore the hardware plate material which is arranged in the middle of the clamping plate is driven to move on the upper side of the workbench, labor intensity of workers is greatly reduced, and production efficiency is improved.

Drawings

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

FIG. 2 is a left side view of the present invention;

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

FIG. 4 is a schematic view of the enlarged structure of part A of the present invention.

In the figure: 1 workbench, 2 pylons, 3 pylons, 4 first sliding shafts, 5 annular rotating grooves, 6 first gears, 7 second gears, 8 first rotating shafts, 9 fixing plates, 10 first electric telescopic rods, 11 sliding holes, 12 clamping plates, 13 second sliding shafts, 14 bottom supporting plates, 15 second rotating shafts, 16 supporting rotating cylinders, 17 annular fixing plates, 18 servo motors, 19 placing plates, 20 double-shaft motors, 21 mounting holes, 22 upright posts, 23 triangular fixing ribs, 24 mounting plates, 25U-shaped supporting plates, 26V-shaped wheels, 27PLC controllers, 28V-shaped belts, 29L-shaped connecting rods, 30 lead screws, 31 guide posts, 32 second electric telescopic rods, 33 connecting plates, 34 arc-shaped through grooves and 35 pressing plates.

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. 1-4, the present invention provides a technical solution: an automatic clamping and moving mechanism for hardware plates comprises a workbench 1, two groups of symmetrically distributed placing plates 19 are arranged on two sides of the workbench 1 and used for placing the hardware plates and convenient to move, two groups of symmetrically distributed first sliding shafts 4 are arranged on one side, close to the workbench 1, of the placing plates 19, a U-shaped supporting plate 25 is arranged on the lower side of the workbench 1, a servo motor 18 is arranged on one side of the U-shaped supporting plate 25, one side, close to the servo motor 18, of the U-shaped supporting plate 25 is connected with an annular fixing plate 17 through a hexagonal bolt, a PLC (programmable logic controller) 27 is arranged on one side, away from the servo motor 18, of the U-shaped supporting plate 25, an output shaft of the servo motor 18 is connected with one end of a rotating shaft through a coupling, the other end of the rotating shaft penetrates through the U-shaped supporting plate 25 and is connected with a lead screw, two sets of L-shaped connecting rods 29 which are symmetrically distributed are connected to two sides of the guide post 31, one end of the upper part of each L-shaped connecting rod 29 is connected with a fixing plate 9, a first sliding shaft 4 is connected with the sliding holes 11 through sliding holes 11 which are arranged at corresponding positions of the L-shaped connecting rods 29 in a sliding manner, column grooves 3 which are uniformly distributed at equal intervals are arranged inside the workbench 1, the middle positions of the column grooves 3 are connected with a first rotating shaft 8 through bearings, the middle position of the outer side of the first rotating shaft 8 is provided with a supporting rotating drum 16 for supporting hardware plates and facilitating rotating movement, the outer side of the supporting rotating drum 16 is provided with an anti-skidding layer, one end of the first rotating shaft 8 penetrates through the workbench 1 and is connected with a first gear 6, one side of the workbench 1, which is close to the first gear 6, is connected with a second rotating shaft 15 which is uniformly distributed at equal intervals through bearings, the middle position of the outer side of the second, one side intermediate position that workstation 1 was kept away from to fixed plate 9 all is equipped with pylon 2, and one side intermediate position that pylon 2 is close to fixed plate 9 all is equipped with logical groove, and the inside that leads to the groove all is equipped with first electric telescopic handle 10, and the one end that pylon 2 was kept away from to first electric telescopic handle 10 all is connected with splint 12, and first electric telescopic handle 10 and servo motor 18's input is connected to the output of PLC controller 27 electricity respectively.

More than six groups of upright columns 22 are symmetrically distributed on the lower side of the U-shaped supporting plate 25 at equal intervals, and one ends, far away from the U-shaped supporting plate 25, of the upright columns 22 are connected with a mounting plate 24.

The mounting plate 24 is connected with the upright post 22 through more than four groups of triangular fixing ribs 23 which are distributed in equal angle symmetry, and more than four groups of mounting holes 21 which are distributed in equal angle symmetry are arranged on the outer side of the mounting plate 24. Is convenient to be fixedly connected with the ground.

The lower part one side intermediate position that U type backup pad 25 is close to PLC controller 27 is equipped with double-shaft motor 20, and one side that U type backup pad 25 is close to double-shaft motor 20 is equipped with the motor fixed plate, and double-shaft motor 20's input is connected to PLC controller 27's output electricity.

The output shafts of the two-shaft motor 20 are connected with one end of a rotating shaft through a coupler, and the other end of the rotating shaft is connected with a V-shaped wheel 26.

Two groups of symmetrically distributed annular rotating grooves 5 are formed in one side, close to the V-shaped wheel 26, of the supporting rotating drum 16, and the annular rotating grooves 5 are connected with the V-shaped wheel 26 in a matched mode through a V-shaped belt 28. The V-belt 28 cooperates with the V-wheel 26 to facilitate carrying the support drum 16.

The clamping plate 12 is provided with an arc through groove 34 at one side close to the supporting rotary drum 16, and four or more groups of bottom supporting plates 14 are arranged at one side of the clamping plate 12 close to the arc through groove 34 at equal intervals. Bottom sprag board 14 can support the five metals sheet material bottom, and the five metals sheet material of being convenient for removes, and splint 12 all is equipped with the arc and leads to groove 34 near the one side that supports rotary drum 16 and be convenient for the cooperation to support rotary drum 16 and slide.

Two groups of second sliding shafts 13 which are symmetrically distributed are connected between the fixing plates 9, and the second sliding shafts 13 are connected with the clamping plates 12 in a sliding manner through holes which are arranged at corresponding positions of the clamping plates 12. The second sliding shaft 13 can prevent the splint 12 from shaking when moving and clamping.

The upside intermediate position of splint 12 all is equipped with connecting plate 33, and the intermediate position of connecting plate 33 all is equipped with second electric telescopic handle 32, and second electric telescopic handle 32's input is connected to PLC controller 27's output electricity.

One end of the second electric telescopic rod 32 close to the workbench 1 is connected with a pressing plate 35, and one side of the pressing plate 35 close to the workbench 1 is provided with a non-slip mat. The pressing plate 35 is used for preventing sliding when the hardware plate is pressed.

When in use: firstly, the hardware plate materials can be placed on the upper side of the placing plate 19, then the hardware plate materials are pushed to the workbench 1 by a worker, when the hardware plate materials are pushed to the upper side of the supporting rotary drum 16, the double-shaft motor 20 is controlled to be opened through the PLC 27, two groups of output shafts of the double-shaft motor 20 rotate to drive the rotating shafts to rotate, the rotating shafts rotate to drive the V-shaped wheels 26 to rotate, the V-shaped wheels 26 rotate to drive the supporting rotary drum 16 to rotate through the V-shaped belts 28, the supporting rotary drum 16 rotates to drive the first rotating shaft 8 arranged at the middle position to rotate, the first rotating shaft 8 rotates to drive the first gear 6 connected with one end to rotate, the first gear 6 rotates to drive the second gear 7 engaged with the second gear 7 to rotate, the second gear 7 rotates to drive the other group of first gears 6 engaged with the gears to rotate, thereby sequentially engaging and driving all the supporting, when the transfer is made to the middle position of the clamping plate 12, the worker turns off the two-shaft motor 20 under the control of the PLC controller 27, then the PLC 27 controls to open the first electric telescopic rod 10, the first electric telescopic rod 10 telescopically pushes the connected clamping plate 12 to move along the axial direction of the second sliding shaft 13, thereby clamping the hardware plate, at the moment, the PLC controller 27 controls the opening of the second electric telescopic rod 32, the second electric telescopic rod 32 stretches and pushes the connected pressing plate 35 to press the hardware plate again, the servo motor 18 is controlled to be turned on through the PLC 27, an output shaft of the servo motor 18 rotates to drive a connected rotating shaft to rotate, the rotating shaft rotates to drive the lead screw 30 to rotate, and the lead screw 30 rotates to drive the guide pillar 31 in threaded connection to move along the axis direction of the first sliding shaft 4, so that the hardware plate arranged in the middle of the clamping plate 12 is driven to move.

The invention has the beneficial effects that: 1. the placing plates 19 arranged on the two sides of the workbench 1 can be used for placing and storing the hardware plates, and when the hardware plates are clamped and moved, the hardware plates can be directly pushed to the upper side of the supporting rotary drum 16 from the placing plates 19, so that the operation of workers is facilitated, and the operation is rapid and convenient;

2. two groups of output shafts of the double-shaft motor 20 rotate to drive the V-shaped wheels 26 to be matched with the V-shaped belt 28, the annular rotary groove 5 and the like to drive one group of the supporting rotary drums 16 to rotate, and then the supporting rotary drums 16 are driven to rotate by gear meshing of the first gear 6 and the second gear 7, so that the positions of the hardware plates can be rapidly moved in a labor-saving manner, the friction force during movement of the hardware plates is greatly reduced, and the time and the labor are saved;

3. the clamping plates 12 connected through telescopic pushing of the first electric telescopic rod 10 move along the axis direction of the second sliding shaft 13, so that two sides of the hardware plate are clamped, the position of the hardware plate can be quickly adjusted, the hardware plate can be quickly clamped and fixed, and the hardware plate is clamped on the upper side of the workbench 1;

4. the pressing plate 35 connected with the second electric telescopic rod 32 in a telescopic pushing mode presses the hardware plate downwards, so that the lower side of the hardware plate is attached to the upper side of the bottom supporting plate 14, the upper side and the lower side of the hardware plate are fastened and fixed, the hardware plate is fastened and fixed in all directions by being matched with the clamping plate 12, and the situation of shaking is prevented;

5. the output shaft of the servo motor 18 rotates to drive the connected lead screw 30 to rotate, the lead screw 30 rotates to drive the guide pillar 31 in threaded connection to move along the axis direction of the first sliding shaft 4, and therefore the hardware plate materials arranged in the middle of the clamping plate 12 are driven to move on the upper side of the workbench 1, labor intensity of workers is greatly reduced, and production efficiency is improved.

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.