阅读说明：本技术 切削刀片及切削刀具 (Cutting insert and cutting tool ) 是由 刘东亨 于 2020-03-27 设计创作，主要内容包括：本发明提供了一种切削刀片及切削刀具。所述切削刀片沿着旋转中心轴从后端向前端延伸,具有以旋转中心轴为分界分成的第一区域和第二区域；所述切削刀片包括第一拘束面和第二拘束面、外周部、贯通孔和切刃；切刃具有和旋转中心轴相交的前端切刃以及位于外周部的第一区域的第一切刃；第一拘束面具有从后端侧向前端侧延伸的冷却槽；所述冷却槽包括入口段、过渡段和多个喷射段；从所述第一拘束面的正视图看,所述多个喷射段与所述过渡段平滑连接,并且具有向着所述前端切刃延伸的第一喷射段。本发明可减小向着前端切刃喷射的冷却剂的流压损失,提高冷却剂冷却效果,从而提高刀片寿命和工件加工表面质量。(The invention provides a cutting insert and a cutting tool. The cutting insert extends from a rear end to a front end along a rotation center axis, and has a first region and a second region divided by the rotation center axis; the cutting blade comprises a first constraint surface, a second constraint surface, an outer peripheral part, a through hole and a cutting edge; the cutting blade has a front cutting blade intersecting the rotation central axis and a first cutting blade located in a first region of the outer peripheral portion; the first restraining surface has a cooling groove extending from the rear end side to the front end side; the cooling tank comprises an inlet section, a transition section and a plurality of injection sections; the plurality of jet segments are smoothly connected with the transition segment and have a first jet segment extending toward the front cutting edge when viewed in front elevation of the first containment surface. The invention can reduce the loss of flow pressure of the coolant sprayed towards the front end cutting edge and improve the cooling effect of the coolant, thereby prolonging the service life of the blade and improving the quality of the processed surface of a workpiece.)

1. A cutting insert extending along a central axis of rotation from a rear end to a front end; the cutting insert has a first region and a second region divided by a central axis of rotation; the method is characterized in that:

the cutting insert has:

two restraining surfaces with a first restraining surface and a second restraining surface which are opposite;

an outer peripheral portion located between the two constraining surfaces;

a through hole formed between the two restraining surfaces;

a cutting blade formed on the front end side;

the cutting edge has:

a front end cutting edge intersecting the rotation center axis;

a first cutting edge located in the first region of the outer peripheral portion;

the outer peripheral portion further having a relief surface located between the first cutting edge and the first constraint surface;

the first restraining surface has a cooling groove extending from a rear end side to a front end side;

the cooling tank includes:

an inlet section extending from the rear end side;

the transition section is connected with one end of the inlet section, which is close to the through hole, and extends along the through hole in a bending way;

a plurality of jetting sections which are respectively connected with the transition sections and respectively extend from the transition sections to ridge lines where the first constraint surfaces and the outer peripheral parts are intersected;

the plurality of jet segments are smoothly connected with the transition segment and have a first jet segment extending toward the front cutting edge when viewed in front elevation of the first containment surface.

2. The cutting insert according to claim 1, wherein the inlet section extends forwardly from a center of the rear end.

3. The cutting insert according to claim 1, wherein the inlet section is located entirely in the first region.

4. The cutting insert according to claim 1, wherein a depth of the first jet section is shallower than a depth of the transition section.

5. The cutting insert according to claim 1, wherein the cutting edge further has a second cutting edge located in the second region of the peripheral portion;

the outer peripheral portion further has a chip discharge groove located between the first restraining surface and the second cutting edge;

the plurality of injection sections also have a second injection section smoothly connected with the transition section and extending toward the chip discharge flute.

6. The cutting insert according to claim 5, wherein the depth of the second jet section is shallower than the depth of the transition section.

7. The cutting insert according to claim 6, wherein the depth of the second jet section and the depth of the first jet section are equal.

8. The cutting insert according to claim 1, wherein the transition section and the inlet section are smoothly connected.

9. The cutting insert according to claim 1, wherein the inlet section extends linearly.

10. The cutting insert according to claim 9, wherein the inlet section extends obliquely to the first region with respect to the center of rotation axis.

11. The cutting insert according to claim 1, wherein the width of the inlet section tapers away from the rear end.

12. The cutting insert according to claim 1, wherein the plurality of jetting sections each extend linearly.

13. The cutting insert according to claim 1, wherein at least one of the jetting sections extends in a smooth curve.

14. The cutting insert according to claim 1, wherein the junctions of the plurality of jet sections and the transition section are each located in the first region.

15. The cutting insert according to claim 1, wherein the depth of the cooling groove becomes gradually shallower away from the rear end.

16. The cutting insert according to claim 15, wherein the bottom surface of the cooling slot lies in a plane that is inclined relative to the first restraint surface and that is at an angle relative to the first restraint surface.

17. The cutting insert according to claim 15, wherein the bottom surface of the cooling slot is a smoothly transitioning curved surface.

18. A cutting tool comprising a shank and a cutting insert according to any one of claims 1-17, the shank having a coolant channel therein; the cutting insert is mounted to the front end of the tool holder, and the cooling groove of the cutting insert is in communication with the coolant passage.

Technical Field

The invention relates to the technical field of cutting tools, in particular to a cutting blade and a cutting tool.

Background

In cutting of metal materials, end mills are often used for copying, curved surface machining, and the like. The end milling cutter is often processed in a semi-closed environment, and has the problems of difficult discharge of scrap iron, scrap biting of a cutting edge and the like. These factors all reduce tool life and affect the surface quality of the workpiece, and the provision of a cooling system can solve the above problems to varying degrees. But the prior art still has certain disadvantages.

Chinese patent CN101695770A discloses a blade finish milling cutter with an internal cooling system, which is provided with a through hole along the central axis of the cutter holder, and a cooling groove and a jet orifice on the blade. The through hole of the cutter handle is communicated with the cooling groove of the blade, and the cutting edge is cooled through the jet orifice.

In this solution, the channel connecting the inlet of the cooling channel with the injection orifice surrounds the central through hole, and when the coolant reaches the channel inlet of the blade, it is immediately blocked by the cylinder formed by the through hole, and is divided into two streams, which are injected towards the outlet after filling the channel, during which both the flow rate and the pressure are lost to a certain extent.

Disclosure of Invention

It is an object of the present invention to provide a cutting insert having cooling grooves to improve tool life and surface quality of a workpiece.

It is another object of the present invention to provide a cutting tool comprising the cutting insert described above.

In order to solve the technical problems, the invention adopts the following technical scheme:

according to one aspect of the present invention, there is provided a cutting insert extending from a rear end to a front end along a central axis of rotation; the cutting insert has a first region and a second region divided by a central axis of rotation; the cutting insert has: two restraining surfaces with a first restraining surface and a second restraining surface which are opposite; an outer peripheral portion located between the two constraining surfaces; a through hole formed between the two restraining surfaces; a cutting blade formed on the front end side; the cutting edge has: a front end cutting edge intersecting the rotation center axis; a first cutting edge located in the first region of the outer peripheral portion; the outer peripheral portion further having a relief surface located between the first cutting edge and the first constraint surface; the first restraining surface has a cooling groove extending from a rear end side to a front end side; the cooling tank includes: an inlet section extending from the rear end side; the transition section is connected with one end of the inlet section, which is close to the through hole, and extends along the through hole in a bending way; a plurality of jetting sections which are respectively connected with the transition sections and respectively extend from the transition sections to ridge lines where the first constraint surfaces and the outer peripheral parts are intersected; the plurality of jet segments are smoothly connected with the transition segment and have a first jet segment extending toward the front cutting edge when viewed in front elevation of the first containment surface.

According to another aspect of the present invention, there is provided a cutting tool comprising a shank and a cutting insert as described above, the shank having a coolant channel therein; the cutting insert is mounted to the front end of the tool holder, and the cooling groove of the cutting insert is in communication with the coolant passage.

According to the technical scheme, the invention has at least the following advantages and positive effects: the cutting blade is provided with the cooling groove on the constraint surface, the cooling groove is provided with a plurality of spraying sections for cooling the cutting edge, wherein the first spraying section of the cooling groove, which extends towards the front end cutting edge, is smoothly connected with the transition section, so that the pressure loss of the coolant sprayed from the first spraying section towards the front end cutting edge is greatly reduced compared with the prior art, the spraying effect of the coolant is improved, the heat dissipation and the chip discharge at the front end cutting edge are facilitated, the processing surface quality of a workpiece is improved, and the service life of the cutting blade is prolonged.

Drawings

Fig. 1 is a perspective view of an embodiment of a cutting insert of the present invention.

Fig. 2 and 3 are front views of fig. 1.

Fig. 4 is a schematic cross-sectional view of C-C in fig. 2.

Fig. 5 is a schematic cross-sectional view taken along line D-D of fig. 2.

Fig. 6 is a schematic cross-sectional view E-E of fig. 2.

Fig. 7 is a sectional view taken along line G-G in fig. 2.

Fig. 8 is a cross-sectional view of another embodiment of a cutting insert, the view being in the direction of fig. 7.

Fig. 9 is a cross-sectional view of yet another embodiment of a cutting insert, the view being in the direction of fig. 7.

Fig. 10 is a perspective view of an embodiment of the cutting tool of the present invention.

The reference numerals are explained below:

l, a rotating central shaft; B. a back end; F. a front end; a1, a first area; a2, second area;

1. a cutting insert;

11. a restraining surface; 111. a first restraining surface; 112. a second constraint surface;

12. a peripheral portion; 121. a rear corner face; 1211. a main rear corner face; 1212. a minor back corner face; 122. a chip discharge groove; 123. a front corner face; 124. a bevel;

13. a through hole;

14. cutting edges; 141. a front end cutting edge; 142. a first cutting edge; 143. a second cutting edge;

15. a cooling tank; 151. an inlet section; 152. a transition section; 153. a spraying section; 153a, a first injection section; 153b, a second injection section; 155. a plane; 156. a curved surface;

2. a knife handle; 21. a knife handle main body; 211. a coolant passage; 22. a knife jaw;

3. and (5) fastening the screw.

Detailed Description

Exemplary embodiments that embody features and advantages of the invention are described in detail below in the specification. It is to be understood that the invention is capable of other embodiments and that various changes in form and details may be made therein without departing from the scope of the invention and the description and drawings are to be regarded as illustrative in nature and not as restrictive.

Referring to fig. 1 and 2, one embodiment of the present invention provides a cutting insert 1, the cutting insert 1 extending along a central axis of rotation L from a rear end B to a front end F. The cutting insert 1 has a first region a1 and a second region a2 divided by a central axis of rotation L.

The cutting insert 1 has two opposing restraining surfaces 11, an outer peripheral portion 12 located between the two restraining surfaces 11, a through hole 13 formed between the two restraining surfaces 11, a cutting edge 14 formed on the tip side, and a cooling groove 15 provided on the restraining surfaces 11.

The two restraining surfaces 11 are parallel to each other and are the front and back surfaces of the cutting insert 1, and the two restraining surfaces 11 are 180-degree rotationally symmetrical. For convenience of description, the two restraining surfaces 11 are referred to as a first restraining surface 111 and a second restraining surface 112, respectively.

The cutting blade 14 has a leading cutting edge 141 intersecting the rotation center axis L, a first cutting edge 142 located in the first region a1, and a second cutting edge 143 located in the second region a 2. The front end cutting edge 141, the first cutting edge 142 and the second cutting edge 143 are connected to form a space curve. The first cutting edge 142 and the second cutting edge 143 have 180-degree rotational symmetry.

As shown in fig. 2, the cutting insert 1 of the present embodiment is a ball end mill insert, the cutting edge 14 is projected on a semicircle, and the profile of the cutting edge 14 rotating about the rotation center axis L forms a hemisphere, so that spherical surface machining can be performed.

In other embodiments, not shown, the extension shape of the cutting edge 14 is not limited to the spatial circular arc shape, but may be a plane, a spatial curve, or the like, so that the cutting insert 1 forms other types of tools, such as a flat angle end mill, a circular arc end mill, or the like.

The through hole 13 is circular and concentric with the semicircle projected by the cutting edge 14. The axis (not shown) of the through hole 13 intersects the rotation center axis L.

The outer peripheral portion 12 intersects with the two restraining surfaces 11. The outer peripheral portion 12 has a ridge line to form the cutting edge 14. The outer peripheral portion 12 has a relief surface 121 located between the first cutting edge 142 and the first constraint surface 111 corresponding to the first cutting edge 142, wherein the relief surface 121 includes a primary relief surface 1211 contacting the first cutting edge 142 and a secondary relief surface 1212 contacting the first constraint surface 111. The outer peripheral portion 12 has a rake surface 123 contacting the second cutting edge 143 and a slope surface 123 contacting the first restraining surface 111, corresponding to the second cutting edge 143, and the rake surface 123 contacts the slope surface 123 to form a chip discharge groove 122 therebetween. The relief surface 121 intersects the chip discharge groove 122 at the rotation center axis L and corresponds to the leading edge 141.

The cooling groove 15 extends from the rear end side to the front end side. In this embodiment, the cooling grooves 15 on the first restraining surface 111 and the cooling grooves 15 on the second restraining surface 112 are arranged in 180-degree rotational symmetry.

As shown in fig. 1 and 2, the cooling groove 15 on the first restraining surface 111 will be specifically described as an example.

In the present embodiment, the cooling slot 15 includes an inlet section 151, a transition section 152, and two injection sections 153.

The inlet section 151 extends forward from the rear end side. In this embodiment, the inlet section 151 extends forward from the center of the rear end of the cutting insert 1, facilitating the introduction of the coolant.

Wherein the width of the inlet section 151 is also gradually narrowed as it goes away from the rear end so that the coolant flow rate can be gradually increased.

In some embodiments, the inlet segment 151 is located entirely within the first region a1, thereby leaving a larger restraining area for the second region a2, compensating for the area loss of the second region a2 due to the chip discharge slots 122, and improving the restraining effect.

In this embodiment, the inlet section 151 extends along a straight line, facilitating coolant flow, reducing flow velocity and pressure loss. The inlet section 151 extends obliquely to the first area a1 relative to the central axis of rotation L, and forms an included angle with the central axis of rotation L, so as to facilitate the smooth transition between the inlet section and the transition section 152, and at the same time, the second area a2 can have a larger restraining area. In some embodiments, the inlet segment 151 may also be a curve with a larger curvature.

The transition section 152 is connected to one end of the inlet section 151 near the through hole 13 and extends along the through hole 13 in a curved manner. Specifically, the transition section 152 has an arc shape, is substantially concentric with the through hole 13, and is spaced apart from the through hole 13. The transition section 152 is also located entirely within the first region a1, and extends from the rear end side to the front end side around the through hole 13. In other embodiments, the transition section 152 may have other curved shapes extending in a curved manner.

The two injection segments 153 are respectively connected to the front end of the transition segment 152, and respectively extend from the transition segment 152 to the ridge line where the first constraint surface 111 intersects with the outer peripheral portion 12.

The joint of the two jetting sections 153 and the transition section 152 is located in the first area a1, so that the first constraint surface 111 has a larger constraint area in the area between the two jetting sections 153, which facilitates the dispersion of stress and improves the constraint effect of the front end of the cutting insert 1.

In this embodiment, the two injection segments 153 are a first injection segment 153a extending toward the front end cutting edge 141 and a second injection segment 153b extending toward the second cutting edge 143.

In the front view of the first constraining surface 111 illustrated in fig. 2, the first spraying section 153a is smoothly connected with the transition section 152 and extends to the cutting edge of the cutting insert 1 to cool the front cutting edge 141 and facilitate chip removal. In the cutting insert 1, the cutting speed at the tip is zero, and the cooling groove 15 and the first spraying section 153a thereof are designed in the present embodiment, so that the heat dissipation and chip removal conditions at the front-end cutting edge 141 are improved, and the problems of difficult heat dissipation at the tip, difficult chip removal and the like in the conventional cutting insert 1 can be overcome. And, the loss of the flowing pressure of the coolant sprayed toward the front end cutting edge 141 is greatly reduced compared to the prior art, and the effect of spraying the coolant is improved, thereby facilitating the heat dissipation and chip discharge of the front end cutting edge 141, improving the quality of the machined surface of the workpiece and prolonging the service life of the cutting insert.

In this embodiment, the first injection section 153a extends linearly, so that the coolant flow loss is small and the machining is convenient. In other embodiments, the first injection segment 153a may also extend in a smooth curve, such as a circular arc, an elliptical arc, a complex curve, and the like.

Here, regarding the smooth connection of the first injection section 153a and the transition section 152, it can be understood that: in the front view shown in fig. 2 and 3, the first injection section 153a and the transition section 152 have no step difference and no obvious bend at the junction. Although manufacturing tolerances may exist, generally the following condition can be satisfied where the first injection section 153a joins the transition section 152:

as shown in FIG. 3, on the boundary line where the first injection segment 153a and the transition segment 152 are connected, any two points P1, P2 are taken, the two points P1, P2 are crossed to form a tangent line of the boundary line, and the distance between the two points P1, P2 is less than H_MAXWhen the angle alpha between tangents at the two points P1 and P2 is less than or equal to 16 degrees. Wherein H_MAXRefers to the maximum depth of the cooling channel 15, with respect to H_MAXSee fig. 7 and 8 for an illustration of the same.

In addition, the above condition is also satisfied if any two points spaced apart at the junction of the centerlines of the first injection section 153a and the transition section 152, as measured by the centerlines of the two. Wherein the centerline is defined as: the direction perpendicular to the flow direction of the coolant is defined as the width direction of the cooling bath 15, and an imaginary line passing through the center line in the width direction is defined as the center line of the cooling bath 15.

Referring to fig. 2 and 3, the second spraying section 153b extends to the chip discharge groove 122 corresponding to the second cutting edge 143, and cools the second cutting edge 143 and assists chip discharge. In a front view, a cutting edge radiation angle corresponding to an intersection point of the extension line of the second injection segment 153b and the second cutting edge 143 is approximately within a range of 30 to 50 degrees, and the radiation angle is high in the frequency of use of the cutting edge, so that a better cooling effect can be achieved, and the coolant can be favorably diffused. The cutting edge radiation angle is an included angle between a line connecting a certain point on the cutting edge to the center of the through hole 13 and the rotation central axis L.

In this embodiment, the second injection section 153b also extends linearly, so that the flow loss is small and the processing is convenient. Likewise, the second injection segment 153b may also extend in a smooth curve, such as a circular arc, an elliptical arc, a compound curve, and the like.

Preferably, the second injection section 153b is also smoothly connected with the transition section 152. Reference is made to the foregoing for the definition of "smooth join". As shown in FIG. 3, the boundary line where the second injection segment 153b and the transition segment 152 meet is arbitrarily set at an interval H_MAXThe included angle beta between the two points P3 and P4 and the tangent line of the boundary line passing through the two points P3 and P4 is less than or equal to 16 degrees.

Still referring to fig. 3, preferably, the transition section 152 is also smoothly connected with the inlet section 151. Similarly, the boundary line on the side of the through-hole 13 where the transition section 152 and the inlet section 151 meet is arbitrarily set at an interval H_MAXThe included angle theta between the two points P5 and P6 and the tangent line of the boundary line passing through the two points P5 and P6 is less than or equal to 16 degrees. On the boundary line of the junction between the transition section 152 and the inlet section 151 on the side departing from the through hole 13, the distance is H_MAXThe included angle gamma between the two points P7 and P8 and the tangent line of the boundary line passing through the two points P7 and P8 is less than or equal to 16 degrees.

Therefore, in the whole flowing process of the coolant, the coolant enters from the inlet section 151, passes through the transition section 152, and is finally sprayed to the front end cutting edge 141 by the first spraying section 153a and sprayed to the second cutting edge 143 by the second spraying section 153b, and both the flow rate and the pressure loss in the whole flowing process can be greatly reduced compared with the prior art, and the final spraying effect is improved.

Further, in conjunction with fig. 4 and 5, the depth h2 of the first injection section 153a is shallower than the depth h1 of the transition section 152, i.e., h2 < h1, so that the flow rate and pressure of the coolant after entering the first injection section 153a can be increased, and heat dissipation and chip discharge of the front end cutting edge 141 can be facilitated. In the present embodiment, the width of the first injection section 153a is smaller than the width of the transition section 152. In other embodiments, the width of the first injection section 153a may also be the same as the width of the transition section 152.

Referring to fig. 4 and 6, the depth h3 of the second spraying section 153b is shallower than the depth h1 of the transition section 152, i.e., h3 < h1, so that the flow rate and pressure of the coolant entering the second spraying section 153b can be increased, and heat dissipation and chip discharge of the second cutting edge 143 are facilitated. In the present embodiment, the width of the second injection section 153b is smaller than the width of the transition section 152. In other embodiments, the width of the second injection section 153b may also be the same as the width of the transition section 152.

In some embodiments, the first injection section 153a and the second injection section 153b have the same depth and the same width, so that the injection effect of the two injection sections 153 is approximately equivalent, and the flow distribution is more uniform when the flow is branched from the transition section 152 to the two injection sections 153.

As can be seen from fig. 4 to 6, the cross section of the cooling groove 15 can be designed in various forms, which is beneficial for the passage of the coolant, such as a semicircle, a U shape, an inverted trapezoid, etc. And the section of the cooling groove 15 can be adaptively changed according to the change of the width and the depth at different positions in the extending direction of the cooling groove 15.

Referring to fig. 2, 7 and 8, in some embodiments, the cooling slot 15 has a depth that gradually decreases from the rear end to the front end along its extension, and has a maximum depth H at the inlet of the inlet section 151 at the rear end_MAXThe outlet of the jet section 153 has a minimum depth. Thereby facilitating a gradual increase in flow rate and pressure of the coolant. At the same time, the depth becomes gradually shallower, i.e. cooledThe bottom surface of the groove 15 is smoothly transited, and the flow velocity and pressure loss of the coolant are also reduced.

In the structure shown in fig. 7, the entire bottom surface of the cooling groove 15 is located on a single plane 155, and the plane 155 is inclined with respect to the first restraint surface 111 at an angle δ to the first restraint surface 111. In some embodiments, the included angle δ is preferably 0.5 ° to 5 °.

In the structure shown in fig. 8, the bottom surface of the cooling groove 15 is a smoothly-transitional curved surface 156, and in this structure, the depth of the cooling groove 15 may be gradually reduced. The smooth transition surface 156 of the cooling slot 15 substantially satisfies the following condition: on the curved surface 156, the interval H is taken along the center line of the cooling bath 15_MAXAny two points pass through the two points to form a vertical plane perpendicular to the first constraint surface 111, the two points pass through the vertical plane to form a tangent line of a central line, and an included angle between the two tangent lines is less than or equal to 16 degrees, and is optimally 0-5 degrees.

Referring again to FIG. 9, in some embodiments, it is also possible to provide only the injection section 153 of the cooling slot 15 with a gradually shallower depth away from the aft end, while the depth of the inlet section 151 and transition section 152 remain constant. In this case, the bottom surface of the cooling groove 15 is a flat surface or a gently curved surface inclined with respect to the first restraint surface 111 at the injection section 153, and the bottom surface of the cooling groove 15 is a flat surface at the inlet section 151 and the transition section 152. In this configuration, the coolant may still gradually increase in flow rate and pressure after entering the injection section 153. However, in the inlet section 151 and the transition section 152, the coolant can be pressurized at an increased rate, if necessary, by gradually reducing the width of the inlet section 151 and the transition section 152.

Referring to fig. 10, there is also provided a cutting tool according to an embodiment of the present invention, comprising a tool shank 2 and a cutting insert 1 as described above.

The holder 2 extends forward and backward along the rotation center axis L and includes a holder main body 21 and two spaced jaws 22 provided at the front end of the holder main body 21. A coolant channel 211 extending forwards and backwards is arranged in the tool holder main body 21, and the coolant channel 211 is communicated with the interval between the two tool jaws 22. The jaw 22 is provided with a fastening hole (not numbered in the drawing).

The cutting insert 1 is mounted between the two jaws 22 of the holder 2, and is fixed by a fastening screw 3 inserted into the jaw 22 and the through hole 13, and the two restraining surfaces 11 of the cutting insert 1 face the two jaws 22, respectively. The cooling groove 15 of the cutting insert 1 communicates with a coolant channel 211 in the tool shank 2.

When the cutting tool is used, the tool holder 2 drives the cutting blade 1 to rotate around the rotation central axis L, and the cutting edge 14 of the cutting blade 1 contacts with a workpiece to machine the workpiece. The coolant is fed from the rear end of the holder 2, enters the cooling groove 15 of the cutting insert 1 through the coolant passage 211, and is sequentially sprayed toward the cutting edge 14 through the inlet section 151, the transition section 152 and the spraying section 153, thereby dissipating heat from the cutting edge 14 and assisting chip discharge. The coolant may be a liquid or a gas.

While the present invention has been described with reference to several exemplary embodiments, it is understood that the terminology used is intended to be in the nature of words of description and illustration, rather than of limitation. As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the meets and bounds of the claims, or equivalences of such meets and bounds are therefore intended to be embraced by the appended claims.