阅读说明：本技术 工件进给装置 (Workpiece feeding device ) 是由 曾继华 董锦蝶 吴小东 邹文武 潘玉俊 韩成利 裴华涛 张军虎 吴海波 于 2021-08-31 设计创作，主要内容包括：本发明提出一种工件进给装置,用于夹持并进给工件,包括：机架,所述机架上设有第一料孔,所述第一料孔用于容置所述工件；第一夹持机构,所述机架上开设安装槽,所述安装槽连通所述第一料孔,所述第一夹持机构设于所述安装槽内,所述第一夹持机构用于夹持所述工件；第二夹持机构,设于所述机架上且位于所述第一料孔的一端,所述第二夹持机构用于夹持所述工件,所述第二夹持机构对所述工件的夹持力大于所述第一夹持机构；顶升机构,设于所述机架上,连接所述第二夹持机构,所述顶升机构用于带动所述第二夹持机构,以移动所述工件。本申请的工件进给装置,通过多个夹持机构进给工件,减少生产过程中拆装次数,并且有效提高加工精度、降低不良率。(The invention provides a workpiece feeding device, which is used for clamping and feeding workpieces and comprises: the device comprises a rack, a first material hole and a second material hole, wherein the rack is provided with the first material hole which is used for accommodating the workpiece; the first clamping mechanism is arranged in the mounting groove and used for clamping the workpiece; the second clamping mechanism is arranged on the rack and positioned at one end of the first material hole, the second clamping mechanism is used for clamping the workpiece, and the clamping force of the second clamping mechanism on the workpiece is greater than that of the first clamping mechanism; the jacking mechanism is arranged on the rack and connected with the second clamping mechanism, and the jacking mechanism is used for driving the second clamping mechanism to move the workpiece. The workpiece feeding device of the application feeds workpieces through the plurality of clamping mechanisms, reduces the number of times of dismounting in the production process, and effectively improves the machining precision and reduces the reject ratio.)

1. A workpiece feeding apparatus for holding and feeding a workpiece, comprising:

the device comprises a rack, a first material hole and a second material hole, wherein the rack is provided with the first material hole which is used for accommodating the workpiece;

the first clamping mechanism is arranged in the mounting groove and used for clamping the workpiece;

the second clamping mechanism is arranged on the rack and positioned at one end of the first material hole, the second clamping mechanism is used for clamping the workpiece, and the clamping force of the second clamping mechanism on the workpiece is greater than that of the first clamping mechanism;

the jacking mechanism is arranged on the rack and connected with the second clamping mechanism, and the jacking mechanism is used for driving the second clamping mechanism to move the workpiece.

2. The workpiece feeding apparatus of claim 1, wherein the jacking mechanism comprises:

the jacking plate is abutted against the rack, a second material hole is formed in the jacking plate, and the second material hole is communicated with the first material hole;

the first driving device is connected with the jacking plate and used for driving the jacking plate to reciprocate along a first direction.

3. The workpiece feeding apparatus according to claim 2, wherein the lifting mechanism further comprises a limiting member, the lifting plate is provided with a limiting hole, the frame is provided with a positioning hole, the limiting member comprises a positioning portion and a limiting portion, the positioning hole receives and abuts against the positioning portion, and the limiting portion is movably disposed in the limiting hole.

4. The workpiece feeding apparatus of claim 1, wherein the second clamping mechanism comprises:

the stop block is arranged on the jacking mechanism;

the push block and the stop block clamp the workpiece;

the second driving device is arranged on the rack and connected with the pushing block, and the second driving device is used for driving the pushing block to be far away from or close to the stop block.

5. The workpiece feeding apparatus of claim 4, wherein a side of the stopper facing the push block is provided with a groove, and the push block is configured to press the workpiece into the groove.

6. The workpiece feeding apparatus of claim 4, wherein the stop block has a threaded bore, a fastener is disposed in the threaded bore, and the fastener connects the stop block and the lift mechanism.

7. The workpiece feeding apparatus of claim 4, wherein the second clamping mechanism further comprises a first guide block and a second guide block, the first guide block is connected to the second driving device, the second guide block abuts against the pushing block, and a first inclined surface on the first guide block abuts against a second inclined surface on the second guide block.

8. The workpiece feeding apparatus of claim 7, wherein the first inclined surface and the second inclined surface are inclined in a second direction, and when the second driving device drives the first guide block to move in the first direction, the first guide block drives the second guide block to push the pushing block to move in a third direction so as to push the pushing block to clamp the workpiece.

9. The workpiece feeding apparatus of claim 1, wherein the first clamping mechanism comprises:

the pressing piece is used for propping the workpiece to the first material hole;

the pull rod is connected with the pressing piece and used for pulling the pressing piece;

one end of the elastic piece is connected to one side, far away from the workpiece, of the pressing piece, and the other end of the elastic piece is connected with the rack.

10. The workpiece feeding apparatus of claim 9, wherein the pull rod comprises:

the rod part is connected with the pressing piece;

a locking part connected to the lever part, the locking part locking the lever part when rotating;

the handle is connected with the rotating part, and the handle is far away from one side of the rack.

Technical Field

The invention relates to the technical field of machining, in particular to a workpiece feeding device.

Background

In the production process of one-die multi-cavity products, the small products need to be clamped and processed for many times, so that the use of various jigs and machines is involved, but the production cost of the whole process is increased easily. On the other hand, although the small-sized products have small sizes, the precision requirement is high, and in the conventional processing process, when the small-sized products are subjected to rotary machining through a numerical control cutter, part of the products are easy to loosen, deviation is caused, and the yield is reduced.

Disclosure of Invention

In view of the above, there is a need for a workpiece feeding device to solve the above problems.

The embodiment of the application provides a work piece feeding device for centre gripping and give the work piece, includes:

the device comprises a rack, a first material hole and a second material hole, wherein the rack is provided with the first material hole which is used for accommodating the workpiece;

the first clamping mechanism is arranged in the mounting groove and used for clamping the workpiece;

the second clamping mechanism is arranged on the rack and positioned at one end of the first material hole, the second clamping mechanism is used for clamping the workpiece, and the clamping force of the second clamping mechanism on the workpiece is greater than that of the first clamping mechanism;

the jacking mechanism is arranged on the rack and connected with the second clamping mechanism, and the jacking mechanism is used for driving the second clamping mechanism to move the workpiece.

In one possible embodiment, the jacking mechanism comprises:

the jacking plate is abutted against the rack, a second material hole is formed in the jacking plate, and the second material hole is communicated with the first material hole;

the first driving device is connected with the jacking plate and used for driving the jacking plate to reciprocate along a first direction.

In a possible implementation manner, the jacking mechanism further includes a limiting member, the jacking plate is provided with a limiting hole, the rack is provided with a positioning hole, the limiting member includes a positioning portion and a limiting portion, the positioning hole is accommodated and abutted against the positioning portion, and the limiting portion is movably disposed in the limiting hole.

In one possible embodiment, the second clamping mechanism comprises:

the stop block is arranged on the jacking mechanism;

the push block and the stop block clamp the workpiece;

the second driving device is arranged on the rack and connected with the pushing block, and the second driving device is used for driving the pushing block to be far away from or close to the stop block.

In a possible embodiment, a side of the stop facing the push block is provided with a groove, and the push block is used for pressing the workpiece into the groove.

In a possible embodiment, a threaded hole is formed in the stopper, a fastening piece is disposed in the threaded hole, and the fastening piece connects the stopper and the jacking mechanism.

In a possible implementation manner, the second clamping mechanism further includes a first guide block and a second guide block, the first guide block is connected to the second driving device, the second guide block abuts against the pushing block, and a first inclined surface on the first guide block abuts against a second inclined surface on the second guide block.

In a possible implementation manner, the first inclined surface and the second inclined surface are inclined along a second direction, and when the second driving device drives the first guide block to move along the first direction, the first guide block drives the second guide block to push the push block to move along a third direction, so as to push the push block to clamp the workpiece.

In one possible embodiment, the first clamping mechanism comprises:

the pressing piece is used for propping the workpiece to the first material hole;

the pull rod is connected with the pressing piece and used for pulling the pressing piece;

one end of the elastic piece is connected to one side, far away from the workpiece, of the pressing piece, and the other end of the elastic piece is connected with the rack.

In one possible embodiment, the tie rod comprises:

the rod part is connected with the pressing piece;

a locking part connected to the lever part, the locking part locking the lever part when rotating;

the handle is connected with the rotating part, and the handle is far away from one side of the rack.

Compared with the prior art, the workpiece feeding device provided by the application feeds workpieces in a clamping mode through the first clamping mechanism and the second clamping mechanism, reduces the dismounting times in the production process of small products, and effectively improves the processing precision and reduces the reject ratio.

Drawings

Fig. 1 is a schematic structural view of a workpiece feeding apparatus according to an embodiment of the present invention.

Fig. 2 is a structural sectional view of the workpiece feeding apparatus shown in fig. 1.

Fig. 3 is a schematic structural view of a second clamping mechanism in the workpiece feeding device shown in fig. 1.

Fig. 4 is a schematic view of another perspective of the workpiece feeding apparatus shown in fig. 1.

Fig. 5 is a schematic structural view of another view of the first clamping mechanism marked by the workpiece feeding device shown in fig. 4.

Description of the main elements

Workpiece feeding apparatus 100

Rack 10

First mounting plate 101

Second mounting plate 102

Support member 103

First material hole 11

Mounting groove 12

Second step surface 121

Positioning hole 13

First clamping mechanism 20

Pressing piece 21

Pull rod 22

Rod part 221

Locking part 222

Handle 223

Elastic member 23

Second clamping mechanism 30

Stopper 31

Groove 311

Threaded hole 312

Push block 32

Second drive device 33

First guide block 331

First inclined plane 3311

Second guide block 332

Second inclined plane 3321

Jacking mechanism 40

Jacking plate 41

Second material hole 411

Limiting hole 412

Accommodating groove 4121

First step surface 4122

First drive device 42

Stopper 43

Positioning part 431

Position limiting part 432

Workpiece 200

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. 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.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly above and obliquely above the second feature, or simply meaning that the first feature is at a lesser level than the second feature.

The following disclosure provides many different embodiments or examples for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or uses of other materials.

Referring to fig. 1 and fig. 2, a workpiece feeding device 100 of the present application is used for clamping and feeding a workpiece 200, and includes a frame 10, wherein a first material hole 11 is formed in the frame 10, and the first material hole 11 is used for accommodating the workpiece 200. The first clamping mechanism 20 is provided with a mounting groove 12 on the frame 10, the mounting groove 12 is communicated with the first material hole 11, the first clamping mechanism 20 is arranged in the mounting groove 12, and the first clamping mechanism 20 is used for clamping the workpiece 200. The second clamping mechanism 30 is arranged on the frame 10 and located at one end of the first material hole 11, the second clamping mechanism 30 is used for clamping the workpiece 200, and the clamping force of the second clamping mechanism 30 on the workpiece 200 is greater than that of the first clamping mechanism 20. The jacking mechanism 40 is arranged on the frame 10 and connected with the second clamping mechanism 30, and the jacking mechanism 40 is used for driving the second clamping mechanism 30 to move the workpiece 200.

It should be noted that the workpiece 200 may be a bar-shaped structure movably disposed in the first material hole 11. The mounting groove 12 is opened on the bottom surface of the upper portion of the frame 10, and one end thereof is communicated with the first material hole 11. One end of the first clamping mechanism 20 is disposed in the mounting groove 12, and applies pressure to the workpiece 200 in the first material hole 11 to press against the workpiece 200, so as to prevent the workpiece 200 from sliding off, and fix the workpiece 200. The second clamping mechanism 30 is disposed on the frame 10, and clamps another portion of the workpiece 200, and the clamping force is greater than that of the first clamping mechanism 20, so as to drive the workpiece 200 to move. The jacking mechanism 40 is connected to the second clamping mechanism 30 to enable the second clamping mechanism 30 to drive the workpiece 200 to displace in the first direction. The first direction in this embodiment is a vertically upward direction a as shown in fig. 1.

In this embodiment, eight first material holes 11 are formed in the frame 10, correspondingly, four sets of first clamping mechanisms 20 are provided, and each set of first clamping mechanism can respectively clamp two workpieces 200, so that the workpiece feeding device 100 can feed eight workpieces at most simultaneously. In other embodiments, the number of the first material holes 11 may be more than or less than half to meet the design requirement, and the number is not limited in the present application. The rack 10 is a substantially rectangular parallelepiped frame having a hollow interior, and includes a first mounting plate 101, a second mounting plate 102, and a support member 103, and the support member 103 is connected between the first mounting plate 101 and the second mounting plate 102. The first material hole 11, the first clamping mechanism 20 and the second clamping mechanism 30 are all arranged on the first mounting plate 101 of the rack 10, and a space between the first mounting plate 101 and the second mounting plate 102 is reserved for the workpiece 200. The second mounting plate 102 is used to position and secure the entire rack 10.

In use, a workpiece 200 is placed into the first feed hole 11 of the workpiece feeding device 100, and the workpiece 200 is fixed by the first clamping mechanism 20. The second clamping mechanism 30 is used for clamping the workpiece 200, and the second clamping mechanism 30 is driven by the jacking mechanism 40 to jack in the first direction. Because the clamping force of the second clamping mechanism 30 is greater than that of the first clamping mechanism 20, the second clamping mechanism 30 can drive the workpiece 200 to move, and after the movement is finished and the second clamping mechanism 30 is released, the first clamping mechanism 20 can still fix the workpiece 200 and prevent the workpiece 200 from sliding off after the movement. This feature achieves the effect of automatically feeding the workpiece 200 by the workpiece feeding device 100.

Referring to fig. 2, in an embodiment, the lifting mechanism 40 includes a lifting plate 41 supported on the frame 10, the lifting plate 41 is provided with a second material hole 411, the second material hole 411 is communicated with the first material hole 11, and the workpiece 200 is partially disposed in the second material hole 411. And a first driving device 42 connected to the frame 10, wherein the first driving device 42 is used for driving the lifting plate 41 to reciprocate along the first direction.

It should be noted that the second material hole 411 is positioned in alignment with the first material hole 11 to facilitate smooth penetration of the bar-shaped workpiece 200. In this embodiment, the lifting plate 41 may be erected above the frame 10, and the first direction is the direction indicated by the arrow a shown in fig. 1. The first driving device 42 may be disposed at a side of the frame 10, and is connected to and drives the lifting plate 41 to lift in the first direction through the frame 10.

In an embodiment, the jacking mechanism 40 further includes a limiting member 43, the jacking plate 41 is provided with a limiting hole 412, the frame 10 is provided with a positioning hole 13, the limiting member 43 includes a positioning portion 431 and a limiting portion 432, the positioning hole 13 is accommodated and abutted against the positioning portion 431, and the limiting portion 432 is movably disposed in the limiting hole 412.

It should be explained that the limiting member 43 may be an approximately screw-shaped member, and the limiting member 43 includes a positioning portion 431 and a limiting portion 432 connected to each other, and the diameter of the positioning portion 431 is smaller than that of the limiting portion 432. The positioning hole 13 is coaxially disposed with the limiting hole 412. The positioning portion 431 has one end disposed in the positioning hole 13 of the frame 10 and the other end received in the limiting hole 412 of the lifting plate 41. The bottom of the limiting hole 412 may be provided with an inward-recessed receiving groove 4121, a first step surface 4122 is formed at a joint of the receiving groove 4121 and the limiting hole 412, and the first step surface 4122 may abut against the limiting portion 432, so as to limit the height of the lifting plate 41. By adjusting the height of the limiting member 43, the height of the jacking plate 41 which can be jacked can be easily adjusted, and the adaptation to different workpieces 200 or processing requirements can be realized.

In one embodiment, the second clamping mechanism 30 includes a stopper 31, and the stopper 31 is disposed on the jacking mechanism 40. The push block 32, together with the stopper 31, holds the workpiece 200. And the second driving device 33 is arranged on the frame 10 and connected with the pushing block 32, and the second driving device 33 is used for driving the pushing block 32 to move away from or close to the stop block 31.

It should be explained that the stopper 31 may be provided on the lift plate 41. The second actuating device drives the pushing block 32 to approach or depart from the stop 31, when the pushing block 32 approaches the stop 31, the clamping of the workpiece 200 is realized, and when the pushing block 32 departs from the stop 31, the workpiece 200 is released, so that the jacking mechanism 40 returns and feeds the next period.

In this embodiment, four pushing blocks 32 and one stopper 31 are provided, each pushing block 32 abuts against the stopper 31, and each pushing block 32 can clamp two workpieces 200. Each push block 32 is in driving connection with a second drive 33. The stopper 31 and the pushing block 32 are provided on the upper surface of the lift plate 41, the stopper 31 is fixedly provided, and the pushing blocks 32 are sequentially arranged on one side of the stopper 31 and are displaced toward the stopper 31 by the respective second driving devices 33. The second driving device 33 is disposed at the bottom of the upper plane of the rectangular parallelepiped frame 10, and is connected to the pushing block 32 through the upper plane of the frame 10. In other embodiments, the number of the pushing blocks 32 and the stoppers 31 may be different, and the application is not limited thereto.

In an embodiment, a groove 311 is formed on one side of the stopper 31 facing the pushing block 32, the pushing block 32 is used for pressing the workpiece 200 into the groove 311, and the number of the grooves 311 is the same as that of the workpieces 200 that can be clamped, and is eight in this embodiment. The position of the groove 311 corresponds to the position of the second material hole 411 on the lifting plate 41, so that the workpiece 200 is ensured to sequentially penetrate through the first material hole 11, the second material hole 411 and the groove 311, the stop block 31 can conveniently and accurately position the workpiece 200, and the machining precision is improved.

In one embodiment, the stopper 31 has a threaded hole 312, and a fastener (not shown) is disposed in the threaded hole 312 and connects the stopper 31 and the lifting mechanism 40. The stopper 31 is connected with the jacking plate 41 through threads, so that the stopper 31 has replaceability, the stoppers 31 in different shapes can be replaced according to different workpieces 200 or processing requirements, and the application range is expanded.

Referring to fig. 3, in an embodiment, the second clamping mechanism 30 further includes a first guiding block 331 and a second guiding block 332, the first guiding block 331 is connected to the second driving device 33, the second guiding block 332 supports the pushing block 32, and a first inclined surface 3311 of the first guiding block 331 supports against a second inclined surface 3321 of the second guiding block 332.

It should be noted that, the first guide block 331 is directly connected to the second driving device 33, and the second driving device 33 can drive the first guide block 331 to displace in the first direction a. Because the first guide block 331 is in contact with the second guide block 332 through the inclined surface, the first guide block 331 drives the second guide block 332 to move in the horizontal direction during the movement in the vertical direction, and further drives the push block 32 to be far away from or close to the stop block 31, so that the workpiece 200 is clamped or loosened. The first guide block 331 and the second guide block 332 can be connected in an embedded manner, so that when the second driving device 33 drives the first guide block 331 to move along the first direction a, the second guide block 332 can drive the push block 32 to return. The second guide block 332 protrudes from a side facing away from the first guide block 331 and is connected to the push block 32.

In one embodiment, the first inclined surface 3311 and the second inclined surface 3321 are inclined along a second direction, which is the direction b in fig. 3. When the second driving device 33 drives the first guide block 331 to move along the first direction, the first guide block 331 drives the second guide block 332 to push the pushing block 32 to move along the third direction, so as to push the pushing block 32 to clamp the workpiece 200. The third direction is a horizontal direction, as indicated by arrow c in fig. 3.

Referring to fig. 4 and 5, in an embodiment, the first clamping mechanism 20 includes a pressing member 21 for pressing the workpiece 200 to the first material hole 11. And a pull rod 22 connected with the pressing piece 21, wherein the pull rod 22 is used for pulling the pressing piece 21. And one end of the elastic piece 23 is connected to the side of the pressing piece 21 far away from the workpiece 200, and the other end is connected with the frame 10.

It should be noted that the elastic member 23 may be an elastic workpiece such as a spring, an elastic plunger, etc., and the pressing member 21 may be made of a relatively soft material to avoid damage when pressing the workpiece 200, and the clamping force of the first clamping mechanism 20 on the workpiece 200 can be controlled to be lower than that of the second clamping mechanism 30 while the workpiece 200 is not dropped, so that the second clamping mechanism 30 drives the workpiece 200 to move forward. In this embodiment, each first clamping mechanism 20 includes two springs, which are distributed on two sides of the pull rod 22 in the mounting groove 12 and jointly act on the pressing member 21 and the frame 10, so that the pressing member 21 is uniformly stressed. In the using process, a user pulls the pull rod 22 outwards to drive the pressing piece 21 outwards so as to place the workpiece 200 in, then the pull rod 22 is loosened, and the elastic piece 23 rebounds to drive the pressing piece 21 to press the workpiece 200 in the first material hole 11, so that the workpiece 200 is clamped and fixed.

In one embodiment, the pull rod 22 includes a rod portion 221, a locking portion 222, and a handle 223. The shaft portion 221 is connected to the pressing member 21. The locking part 222 is connected to the lever part 221, and when the locking part 222 rotates in the direction of the axis of the lever part 221, the lever part 221 can be locked or unlocked. And a handle 223 connected with the rotating part, wherein the handle 223 is far away from the frame 10 side. The pressing member 21 connects the rod portion 221, the locking portion 222, and the handle 223 in this order from the first material hole 11 outward. The locking part 222 may be a rectangular parallelepiped, and the locking part 222 is horizontally accommodated in the mounting groove 12 when the first clamping mechanism 20 clamps the workpiece 200. When the first clamping mechanism 20 is released, the user pulls the handle 223 outwards to drive the locking portion 222 outwards, and then the handle 223 can be rotated, so that the long edge of the cuboid part in the locking portion 222 can realize the effect of locking the pressing portion by abutting against the second step surface 121 formed by the mounting groove 12 and the rack 10. The locking portion 222 is continuously rotated to separate the rectangular solid portion from the second step surface 121, thereby unlocking the lock. The locking portion 222 eliminates the need for the user to pull the handle 223 at all times, facilitates installation of the work piece 200, and reduces the cost of manual operations.

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.

Although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the spirit and scope of the present invention.