阅读说明：本技术 双滚轮式柔性翻边成形装置及工艺 (Double-roller type flexible flanging forming device and process ) 是由 程旋 赵亦希 于忠奇 于 2021-09-02 设计创作，主要内容包括：一种双滚轮式柔性翻边成形装置及工艺,包括：依次转动连接的第一、第二、第三机器关节机构和成形滚轮机构、与第一机器关节机构依次相连的伸缩结构和用于压紧待成形件的压紧滚轮机构,第一机器关节机构一端与第二机器关节机构转动连接,同时与伸缩机构一端联轴器连接,第二机器关节机构与第三机器关节机构一端转动连接,第三机器关节机构另一端与成形滚轮机构螺接固定；伸缩机构另一端与压紧滚轮机构固定连接；通过电子控制单元控制压紧滚轮机构压紧待成形件,以及不断调整成形滚轮机构位姿,即可实现待成形件的多道次翻边成形。本发明根据待成形件的曲面加工要求,通过协调控制机器关节机构、伸缩结构、滚轮机构之间运动,规划滚轮运动轨迹,各机构之间协同控制,装置结构灵活,自由度高,工作空间大,能够实现不同尺寸板材的翻边柔性成形。(A double-roller type flexible flanging forming device and a process thereof comprise: the first, second and third machine joint mechanisms are sequentially and rotationally connected with each other, the forming roller mechanism, the telescopic structure sequentially connected with the first machine joint mechanism and the pressing roller mechanism used for pressing a to-be-formed piece are sequentially connected with each other, one end of the first machine joint mechanism is rotationally connected with the second machine joint mechanism and is simultaneously connected with a coupler at one end of the telescopic mechanism, the second machine joint mechanism is rotationally connected with one end of the third machine joint mechanism, and the other end of the third machine joint mechanism is fixedly connected with the forming roller mechanism in a threaded manner; the other end of the telescopic mechanism is fixedly connected with the pressing roller mechanism; the electronic control unit controls the pressing roller mechanism to press the to-be-formed piece, and the pose of the forming roller mechanism is continuously adjusted, so that multi-pass flanging forming of the to-be-formed piece can be realized. According to the invention, according to the curved surface processing requirement of the piece to be formed, the movement among the machine joint mechanism, the telescopic structure and the roller mechanism is coordinated and controlled, the movement track of the roller is planned, the mechanisms are cooperatively controlled, the device has flexible structure, high degree of freedom and large working space, and the flexible forming of the flanging of the plates with different sizes can be realized.)

1. The utility model provides a flexible turn-ups forming device of double-roller formula which characterized in that includes: rotate first, second, third machine joint mechanism and the shaping gyro wheel mechanism of connection in proper order, with the extending structure that first machine joint mechanism links to each other in proper order and be used for compressing tightly the pinch roller mechanism of treating the shaping piece, wherein: one end of the first machine joint mechanism is rotationally connected with the second machine joint mechanism and is also connected with a coupler at one end of the telescopic mechanism, the second machine joint mechanism is rotationally connected with one end of the third machine joint mechanism, and the other end of the third machine joint mechanism is fixed with the forming roller mechanism in a threaded manner; the other end of the telescopic mechanism is fixedly connected with the pressing roller mechanism; the electronic control unit controls the pressing roller mechanism to press the piece to be formed, and the pose of the forming roller mechanism is continuously adjusted, so that multi-pass flanging forming of the piece to be formed can be realized;

the first machine joint mechanism and the second machine joint mechanism have three degrees of freedom and roll in the same plane, and the first machine joint mechanism is fixed on the horizontal moving device; the third machine joint mechanism has three degrees of freedom and rolls at an angle of 0-270 deg..

2. The double-roller type flexible cuff forming apparatus as claimed in claim 1, wherein said electronic control unit comprises: information receiving module, information contrast calculation module, motion control module, wherein: the information receiving module is connected with the first machine joint structure and transmits position information, the information comparison and calculation module performs comparison and calculation with a theoretical result according to displacement information to obtain local adjustment displacement, the motion control module respectively controls the roller mechanism to compress the plate and the forming roller mechanism to pose according to the local adjustment displacement information, multi-pass flanging forming of a piece to be formed is achieved, and the qualified flanging part is formed through circulation processing.

3. The double-roller type flexible flanging forming device of claim 1, wherein the forming roller mechanism and the pressing roller mechanism are connected with the connecting rods of the corresponding telescopic structures through bolts; the telescopic mechanism is vertically screwed and fixed with the pressing roller mechanism, and the third machine joint mechanism is horizontally screwed and fixed with the forming roller mechanism.

4. The double-roller flexible cuff forming apparatus of claim 1, 2 or 3 wherein said first, second and third machine articulation mechanisms each comprise: joint driving motor, harmonic gear reduction gear, shaft coupling and connecting rod, the inside connection relation of subassembly is: the joint driving motor is connected with the harmonic gear reducer, and the harmonic gear reducer is connected with the connecting rod through a coupler.

5. The double-roller flexible flange forming apparatus as claimed in claim 4, wherein said telescoping mechanism comprises: the electric push rod is connected with the connecting rod through the coupler.

6. The apparatus of claim 4, wherein the forming roller mechanism and the pressing roller mechanism each comprise: the device comprises a roller mechanism base, rollers, a connecting rod and a pressure sensor; the roller of the forming roller mechanism adopts a double-conical roller; the roller of the pressing roller mechanism adopts a round roller.

7. An in-line process based on the double-roller type flexible flanging forming device of any one of claims 1-6 is characterized in that in a process planning stage, a three-dimensional rectangular coordinate system is established by taking a lower plane of a plate to be formed as a datum plane and the center of a circle of the plate to be formed as an origin, a forming roller mechanism is set to move to a motion starting point along an X axis at first, then flanging forming is carried out in a range of (beta/2, -beta/2) around a Y axis, a roller of a pressing roller mechanism moves in a range of (beta/2, -beta/2) along a roller of the forming roller mechanism in an XZ plane, the motion radius of a reference point is set to be consistent with the inner diameter of an original plate, and n-flanging pass forming is set according to a flanging opening angle alpha of a target flanging piece; according to the measured inner diameter R of the original plate₀Arc opening angle beta, thickness d, flanging opening angle alpha of target flanging piece, transition fillet radius r, and length L of compression part of plate to be formed₁Length L of the turned-up portion₂Radius of the roller r_wDistance h from bottom surface of roller to theoretical tangent point of roller and plate when forming_wY-axis coordinate Y of the mold plane₀Calculating to obtain the initial coordinates of the roller of each pass of the forming roller mechanism, namely the initial coordinates of the circle center of the bottom of the roller, and obtaining the movement radius R of each pass of the forming roller in the XZ plane_cThen obtaining the roller movement speed of the pressing roller mechanism according to the roller movement speed of the forming roller mechanism; and in the execution stage, the forming roller mechanism and the pressing roller mechanism are controlled by the industrial six-axis robot according to the initial coordinates of the rollers in each pass obtained through calculation, so that the rapid and accurate forming of the flanging piece is realized.

8. The in-line process as claimed in claim 7, comprising in particular:

i) measuring to obtain the inner diameter R of the original plate₀1200mm, an arc opening angle beta of 90 degrees and a thickness d of 2mm, a flanging opening angle alpha of 120 degrees, a transition fillet radius r of 10mm and a length L of a compression part of the target flanging piece₁Is 100mm and the length L of the turned-up portion₂Is 32 mm; then according to the length L of the turnup part₂Determining the roller radius r_wIs 24mm and the distance h from the bottom surface of the roller to the theoretical tangent point when the roller and the plate are formed_wIs 30 mm;

ii) establishing a three-dimensional rectangular coordinate system by taking the lower plane of the plate to be formed as a reference plane and the circle center of the plate as an origin, wherein the Y-axis coordinate of the plane of the die is Y₀The number of the rollers is 0, the rollers firstly move to the movement starting point along the X axis, and then flanging and forming are carried out in the range of (45 degrees and minus 45 degrees) around the Y axis; the roller of the pressing roller structure moves in an XZ plane within the range of (45 degrees and minus 45 degrees) along with the forming roller, and the movement radius of a reference point is set to be consistent with the inner diameter of the original plate, namely 1200 mm;

iii) setting 6-pass flanging forming according to the flanging opening angle alpha of the target flanging piece being 120 degrees;

iv) by means of R₀、d、α、β、r、L₁、L₂、h_w、y₀Calculating to obtain the initial coordinates of the roller of each pass of the forming roller mechanism, namely the initial coordinates of the circle center of the bottom of the roller, and obtaining the movement radius R of each pass of the forming roller in the XZ plane_c；

The initial coordinates of the roller of each-pass forming roller mechanism specifically comprise:

the first pass X coordinate is: the Y coordinate is: the Z coordinate is:

the second pass X coordinate is: the Y coordinate is: the Z coordinate is:

the X coordinate of the third pass is as follows: the Y coordinate is: the Z coordinate is:

the fourth pass X coordinate is: the Y coordinate is: the Z coordinate is:

the X coordinate of the fifth pass is as follows: the Y coordinate is: the Z coordinate is:

the X coordinate of the sixth pass is as follows: the Y coordinate is: the Z coordinate is:

the movement radius R of each pass of the forming roller in the XZ plane_cThe method specifically comprises the following steps: the first time: and (3) a second pass:and a third step:and a fourth pass:and a fifth pass:and a sixth pass:

v) guiding the initial coordinates of the roller in each pass obtained by calculation into the electronic control unit 7, and setting the movement speed of the roller of the forming roller mechanism to be V_cThe movement speed V of the roller of the pressing roller mechanism is calculated according to the geometric relationship for ensuring that the movement angular speeds of the roller of the forming roller mechanism and the roller of the pressing roller mechanism are consistent_yThe electronic control unit is started to realize the rapid and accurate forming of the flanging piece;

the roller movement speed of the pressing roller mechanism specifically comprises: the first time:and (3) a second pass:and a third step:and a fourth pass: and a fifth pass:and a sixth pass:

Technical Field

The invention relates to a technology in the field of sheet metal part manufacturing, in particular to a double-roller type flexible flanging forming device and a double-roller type flexible flanging forming process.

Background

At present, flanging parts are produced mainly in a flanging forming mode through a fixed die. The fixed mould flanging is formed and needs to be compressed tightly with hold-down mechanism to the one end of treating the formed piece, and the other end passes through the gyro wheel turn-ups, and hold-down mechanism and gyro wheel are mutually independent, can't carry out the cooperativity and take shape, and the turn-ups shaping cooperativity is poor, makes and treats that the formed piece takes shape the in-process atress inhomogeneous, and the shaping precision is relatively poor, simultaneously, to the blank pressing mould that different product designs correspond, the mould utilization ratio is low, and development cost is high, production cycle is long.

Disclosure of Invention

The invention provides a double-roller type flexible flanging forming device and a double-roller type flexible flanging forming process aiming at the defects in the prior art, wherein according to the curved surface processing requirement of a piece to be formed, the movement among a machine joint mechanism, a telescopic structure and a roller mechanism is coordinately controlled, the movement track of a roller is planned, a group of roller mechanisms tightly presses a plate, and a group of roller mechanisms rolls and flanges the plate, so that the flexible forming of the flanging of the plate is realized. The mechanism is cooperatively controlled, the device has flexible structure, high degree of freedom and large working space, and can realize the flexible forming of the flanging of the plates with different sizes.

The invention is realized by the following technical scheme:

the invention relates to a double-roller type flexible flanging forming device, which comprises: rotate first, second, third machine joint mechanism and the shaping gyro wheel mechanism of connection in proper order, with the extending structure that first machine joint mechanism links to each other in proper order and be used for compressing tightly the pinch roller mechanism of treating the shaping piece, wherein: one end of the first machine joint mechanism is rotationally connected with the second machine joint mechanism and is also connected with a coupler at one end of the telescopic mechanism, the second machine joint mechanism is rotationally connected with one end of the third machine joint mechanism, and the other end of the third machine joint mechanism is fixed with the forming roller mechanism in a threaded manner; the other end of the telescopic mechanism is fixedly connected with the pressing roller mechanism; the electronic control unit controls the pressing roller mechanism to press the to-be-formed piece, and the pose of the forming roller mechanism is continuously adjusted, so that multi-pass flanging forming of the to-be-formed piece can be realized.

The electronic control unit comprises: information receiving module, information contrast calculation module, motion control module, wherein: the information receiving module is connected with the first machine joint structure and transmits position information, the information comparison and calculation module performs comparison and calculation with a theoretical result according to displacement information to obtain local adjustment displacement, the motion control module respectively controls the roller mechanism to compress the plate and the forming roller mechanism to pose according to the local adjustment displacement information, multi-pass flanging forming of a piece to be formed is achieved, and the qualified flanging part is formed through circulation processing.

The invention relates to an in-line process based on the double-roller type flexible flanging forming device, which comprises the steps of establishing a three-dimensional rectangular coordinate system by taking the lower plane of a plate to be formed as a reference plane and the circle center of the plate to be formed as an original point at the process planning stage, setting a forming roller mechanism to move to a motion initial point along an X axis, then carrying out flanging formation in a range of (beta/2 to-beta/2) around a Y axis, setting a reference point motion radius to be consistent with the inner diameter of an original plate by a roller of a pressing roller mechanism to move in a range of (beta/2 to-beta/2) along with the roller of the forming roller mechanism in an XZ plane, and setting n times of flanging formation according to a flanging opening angle alpha of a target flanging piece; according to the measured inner diameter R of the original plate₀Arc opening angle beta, thickness d, flanging opening angle alpha of target flanging piece, transition fillet radius r, and length L of compression part of plate to be formed₁Length L of the turned-up portion₂Radius of the roller r_wDistance h from bottom surface of roller to theoretical tangent point of roller and plate when forming_wY-axis coordinate Y of the mold plane₀Calculating to obtain the initial coordinates of the roller of each pass of the forming roller mechanism, namely the initial coordinates of the circle center of the bottom of the roller, and obtaining the movement radius R of each pass of the forming roller in the XZ plane_cThen obtaining the roller movement speed of the pressing roller mechanism according to the roller movement speed of the forming roller mechanism; and in the execution stage, the forming roller mechanism and the pressing roller mechanism are controlled by the industrial six-axis robot according to the initial coordinates of the rollers in each pass obtained through calculation, so that the rapid and accurate forming of the flanging piece is realized.

The three-dimensional rectangular coordinate system has Y-axis coordinate of the mold plane₀Is 0.

Technical effects

The invention integrally solves the problems of poor flanging forming cooperativity, uneven stress in the forming process of a piece to be formed, poor forming precision, low mold utilization rate, high development cost, long production period and the like of designing corresponding edge pressing molds aiming at different products in the prior flanging technology.

Compared with the prior art, the invention provides a plate flanging forming device and a plate flanging forming method, wherein the electronic control unit controls and coordinates the movement among the machine joint mechanism, the telescopic structure and the roller structure according to the curved surface processing requirement of a piece to be formed, the movement track of the roller is planned, the group of roller mechanisms tightly presses a plate, and the group of roller mechanisms rolls and flanges the plate, so that the flexible forming of the plate flanging is realized. The mechanism is cooperatively controlled, the device has flexible structure, high degree of freedom and large working space, and can realize the flexible forming of the flanging of the plates with different sizes.

Drawings

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

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

FIG. 3 is a schematic view of the relative positions of the apparatus and the sheet during the flanging process;

FIG. 4 is a schematic diagram of forming roller and pinch roller speeds;

FIG. 5 is a comparison of the warpage heights of the flanges of the examples.

In the figure: 1. a first machine joint mechanism; 2. a second machine joint mechanism; 3. a third machine joint mechanism; 11. a first joint driving motor; 13. a harmonic gear reducer; 15. a coupling; 17. a connecting rod; 21. a second joint driving motor; 23. a harmonic gear reducer; 25. a coupling; 27 a connecting rod; 31. a third joint driving motor; 33. an RV reducer; 35. a coupling; 37. a connecting rod; 4. a telescoping mechanism; 41. an electric push rod; 43. a connecting rod; 45. a coupling; 5. forming a roller structure; 51. a roller mechanism base; 53. a roller; 55. a connecting rod; 57. a pressure sensor; 6. a pressing roller structure; 61. a roller mechanism base; 63. a roller; 65. a connecting rod; 67. a pressure sensor; 7. an electronic control unit; 8. a plate material; 81 a plate material pressing part; 82 panel flange portions.

Detailed Description

As shown in fig. 1, the present embodiment relates to a double-roller type flexible cuff forming apparatus, including: first, second, third machine joint mechanism 1, 2, 3 and the forming roller mechanism 5 that rotate the connection in proper order, the extending structure 4 that links to each other in proper order with first machine joint mechanism 1 and be used for compressing tightly the pinch roller mechanism 6 of treating forming part 8, wherein: one end of the first machine joint mechanism 1 is rotatably connected with the second machine joint mechanism 2 and is simultaneously connected with a coupler at one end of the telescopic mechanism 4, the second machine joint mechanism 2 is rotatably connected with one end of the third machine joint mechanism 3, and the other end of the third machine joint mechanism 3 is fixedly connected with the forming roller mechanism 5 in a threaded manner; the other end of the telescopic mechanism 4 is fixedly connected with a pressing roller mechanism 6; the electronic control unit 7 controls the pressing roller mechanism 6 to press the to-be-formed piece and continuously adjusts the pose of the forming roller mechanism 5, so that multi-pass flanging forming of the to-be-formed piece can be realized.

The telescopic mechanisms 4 are connected with the corresponding third machine joint mechanisms 3 through couplings.

The forming roller mechanism 5 and the pressing roller mechanism 6 are connected with the connecting rods of the corresponding telescopic structures 4 through bolts.

The first, second and third machine joint mechanisms 1, 2, 3 each include: the joint driving motors 11, 21 and 32, the harmonic gear reducers 13, 23 and 32, the couplers 15, 25 and 35 and the connecting rods 17, 27 and 37 have the following connection relations: the joint driving motor is connected with the harmonic gear reducer, and the harmonic gear reducer is connected with the connecting rod through a coupler.

The telescopic mechanism 4 comprises: electric putter 41, connecting rod 43, shaft coupling 45, electric putter 41 links to each other with connecting rod 43 through shaft coupling 45.

The first machine joint mechanism 1 and the second machine joint mechanism 2 have three degrees of freedom, can roll in the same plane, and the rolling angle is 0-180 degrees, thereby being beneficial to the posture adjustment of the first machine joint mechanism and the second machine joint mechanism in the space position; the first machine joint mechanism is fixed on the horizontal moving device, so that the device can conveniently move in the horizontal direction, can form pieces to be formed with different sizes, and has high forming efficiency.

The third machine joint mechanism 3 has three degrees of freedom and can roll in the same plane, the rolling angle is 0-270 degrees, and the rolling angle in a large range enables the roller mechanism to be capable of flanging to form a large-curvature sheet metal flanging structural member.

The length of the connecting rod 45 of the telescopic mechanism 4 is adjusted to be 0-150cm, so that the pressing roller mechanism 6 has a large telescopic range in the horizontal direction, and the roller pressing of the to-be-formed pieces with different sizes can be met.

The telescopic mechanism 4 is vertically screwed and fixed with the pressing roller mechanism 6, the screwed roller mechanism is convenient for replacing roller mechanisms with different sizes, simultaneously, the roller can be enabled to press a piece to be formed along the vertical direction, the stress strain of the piece to be formed is reduced, the third machine joint mechanism 3 is horizontally screwed and fixed with the forming roller mechanism 5, and the forming roller mechanism 1 has a large adjusting range in the same plane.

The forming roller mechanism 5 and the pressing roller mechanism 6 both comprise: the roller mechanism bases 51 and 61, the rollers 53 and 63 and the connecting rods 55 and 65 can replace different types of roller mechanisms according to different forming requirements, and the structure flexibility is good.

The forming roller mechanism 5 and the pressing roller mechanism 6 are provided with pressure sensors 57 and 67, so that the stress strain of a piece to be formed can be conveniently detected, and the deformation is more uniform; the roller 53 of the forming roller mechanism 5 adopts a double-conical roller which has high universality and is suitable for rolling and flanging different metal sheet metal structural parts; the idler wheel 63 of the pressing idler wheel mechanism 6 adopts a round rolling idler wheel, so that pressing of a to-be-formed piece is facilitated, meanwhile, the round rolling idler wheel is not prone to causing stress concentration, and flanging forming of the to-be-formed piece cannot be influenced.

The electronic control unit 7 comprises: information receiving module, information contrast calculation module, motion control module, wherein: the information receiving module is connected with the first machine joint structure 1 and transmits position information, the information comparison and calculation module performs comparison and calculation with a theoretical result according to displacement information to obtain local adjustment displacement, and the motion control module respectively controls the roller mechanism 6 to press a plate and the forming roller mechanism 5 to pose according to the local adjustment displacement information to realize multi-pass flanging forming of a to-be-formed piece. The above process can be carried out in a circulating manner until a qualified flanged part is formed.

The embodiment relates to a double-roller type flexible flanging forming method based on the device, which comprises the following steps:

firstly, dividing a plate 8 to be formed into a pressing part 81 and a flanging part 82 according to the part characteristics of a target flanging piece;

secondly, measuring to obtain the inner diameter R of the original plate₀1200mm, an arc opening angle beta of 90 degrees and a thickness d of 2mm, the flanging opening angle alpha of the target flanging piece is 120 degrees, the radius r of the transition fillet is 10mm, and the length L of the compression part 81 is L₁Is 100mm and the length L of the turned-up part 82₂Is 32 mm; and then according to the length L of the cuff portion 82₂Determining the radius r of the roller 53_wIs 24mm and the distance h from the bottom surface of the roller 53 to the theoretical tangent point when the roller 53 and the plate 8 are formed_wIs 30 mm;

thirdly, establishing a three-dimensional rectangular coordinate system by taking the lower plane of the plate 8 to be formed as a reference plane and the circle center of the plate 8 as an original point, wherein the Y-axis coordinate of the plane of the die is Y₀The roller 53 moves to the movement starting point along the X axis at first, and then flanging and forming are carried out in the range of (45 degrees, -45 degrees) around the Y axis; the roller 63 of the pressing roller structure 6 moves in an XZ plane within a range of (45 degrees and minus 45 degrees) along with the forming roller 53, and the movement radius of a reference point is set to be consistent with the inner diameter of the original plate, namely 1200 mm;

fourthly, setting 6-pass flanging forming according to the flanging opening angle alpha of the target flanging piece as 120 degrees;

the fifth step, using R₀、d、α、β、r、L₁、L₂、h_w、y₀Calculating to obtain the initial coordinates of the roller of each pass of the forming roller mechanism, namely the initial coordinates of the circle center of the bottom of the roller, and the movement radius of each pass of the forming roller in the XZ planeR_c；

The initial coordinates of the roller of each-pass forming roller mechanism specifically comprise:

the first pass X coordinate is: the Y coordinate is: the Z coordinate is:

the second pass X coordinate is: the Y coordinate is: the Z coordinate is:

the X coordinate of the third pass is as follows: the Y coordinate is: the Z coordinate is:

the fourth pass X coordinate is: the Y coordinate is: the Z coordinate is:

the X coordinate of the fifth pass is as follows: the Y coordinate is: the Z coordinate is:

the X coordinate of the sixth pass is as follows: the Y coordinate is: the Z coordinate is:

the movement radius R of each pass of the forming roller in the XZ plane_cThe method specifically comprises the following steps: the first time: and (3) a second pass:and a third step: and a fourth pass:and a fifth pass: and a sixth pass:

sixthly, guiding the initial coordinates of the roller in each pass obtained by calculation into the electronic control unit 7, and setting the movement speed of the roller 53 of the forming roller mechanism to be V_c200mm/s, in order to ensure that the movement angular velocities of the forming roller mechanism roller 53 and the pressing roller mechanism roller 63 are consistent, the movement velocity V of the pressing roller mechanism roller 63 is calculated according to the geometric relationship_yAnd starting the electronic control unit 7, so that the flanging piece can be quickly and accurately formed.

The roller movement speed of the pressing roller mechanism specifically comprises: the first time:and (3) a second pass:and a third step:and a fourth pass: and a fifth pass:and a sixth pass:

through specific experiments, the plane warping height of the flanging piece obtained by the method is less than 0.5mm and far lower than the forming height of the flanging piece obtained by the existing flanging forming technology by 6.2 mm.

Compared with the prior flanging technology which needs 10 hours of working time for one-time die repair, the invention calculates and adjusts the time needed by the forming of the forming roller structure and the pressing roller structure after finishing the process planning to be only 0.5 hour, thereby greatly improving the forming efficiency; compared with the prior art that the maximum warping height of the flanging piece is 6.2mm, the forming method can enable the maximum warping height to be smaller than 0.5mm, and obviously improves the forming quality.

The foregoing embodiments may be modified in many different ways by those skilled in the art without departing from the spirit and scope of the invention, which is defined by the appended claims and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.