Berg, Hans-erik (Hornbländevägen 9, Örebro, S-703 74, SE)
| 1. | A wire manufacturing arrangement comprising a housing which includes a transit that has a wire inlet of a first diameter and shape, and a wire or wire outlet through which the wire or wire exits after having been worked to said diameter and/or shape characterized in that said housing includes at least one first and one second hole adapted for the accommodation of a first and a second roll, in that said first roll has a first profile and said second role has a second profile; and in that said first and said second rolls are adapted to work said wire therebetween such as to impart to said wire a second diameter and/or shape in accordance with said first and said second profile. |
| 2. | An arrangement according to claim 1, wherein said housing includes a third and a fourth hole adapted for the accommodation of a third and a fourth roll, wherein respective axes of the third and fourth holes extend at right angles in relation to said first and second holes, so that the first and second rolls will work said wire in a first direction and said third and fourth rolls will work. said wire therebetween in a second direction generally at right angles to said first direction. |
| 3. | An arrangement according to claim 1 or 2, wherein the housing has the same form as a wire drawing plate and is adapted for fitting to a wire drawing bench. |
| 4. | An arrangement according to any one of claims 1, 2 or 3, wherein said first, second, third and/or fourth roll have an oval profile, a round profile, a Vshaped profile, a WO 2005/021176 PCT/SE2004/001257 foursided profile or some other appropriate rolling profile. |
| 5. | An arrangement according to any one of claims 1, 34, wherein the housing is cylindrical in shape and has a centrally and axially positioned transit or leadthrough; wherein the first hole in said housing is a radially extending, round throughpenetrating hole and is displaced in a first direction so that an edge on a barrel surface of said first hole will coincide generally with a housing diameter; wherein said second hole in said housing is a round, radially extending throughpenetrating hole which is displaced in a second direction which is generally opposite to said first direction so that an edge on a barrel surface of said first hole will coincide generally with said housing diameter. |
| 6. | An arrangement according to any one of claims 24, wherein said housing is cylindrical in shape and has a centrally positioned and axially extending transit or leadthrough; wherein the first hole in said housing is a through penetrating, radially extending, round hole which is displaced in a first direction so that an edge of a barrel surface associated with said first hole coincides generally with a first housing diameter ; wherein the second hole in said housing is a throughpenetrating, radially extending, round hole which is displaced in a second direction generally opposite to said first direction such that an edge of a barrel surface associated with said first hole coincides generally with said first housing diameter ; wherein the third hole in said housing is a throughpenetrating, radially extending, round hole which is displaced in a third direction so that an edge on a barrel surface of said third hole coincides generally WO 2005/021176 PCT/SE2004/001257 with a second housing diameter, with said second diameter being generally at right angles to said first diameter ; and wherein said fourth hole in said housing is a through penetrating, radially extending, round hole which is displaced in a fourth direction generally opposite to said second direction, so that an edge of a barrel surface associated with said fourth hole coincides generally with the second housing diameter. |
| 7. | An arrangement according to any one of the preceding claims, wherein the arrangement includes cylindrical rolls mounted in said holes; wherein said cylindrical rolls include, in an axial direction, a first slide part, a profiled part, and a second slide part; wherein said first and said second slide parts are adapted to abut and slide against parts of the inner barrel surfaces of said holes, and wherein said profiled parts define therebetween a wire rolling profile. |
| 8. | An arrangement according to any one of the preceding claims, wherein the rolls are mounted in the housing such that said profiled parts will coincide with said transit; and wherein said profiled parts mutually coact to form a common wire rolling profile. |
| 9. | An arrangement according to any one of the preceding claims, wherein the arrangement includes a housing cooling device and a lubricant applicator. |
| 10. | An arrangement according to claim 9, wherein said cooling device includes a cooling agent ; and wherein said cooling agent and lubricant consist of one and the same substance. |
| 11. | WO 2005/021176 PCT/SE2004/001257. |
| 12. | An arrangement according to claim 1, wherein said housing fulfils the requirement of standard ISO 1684. |
| 13. | An arrangement according to any one of the preceding claims, wherein said housing and said rolls are made of hardmetal (sintered tungsten carbide), hard metal, or some other hard, wearresistant material. |
| 14. | An arrangement according to any one of the preceding claims, characterized in that the housing is made of a first hardmetal having a first degree of hardness, and wherein said rolls are made of a different hard metal that has a different degree of hardness to said housing metal, wherein said first hardmetal is harder than the second hard metal, such that the rolls will be the first to wear. |
| 15. | A wire manufacturing draw roll housing which is cylindrical in shape and has a throughpenetrating, central, axial opening through which wire of a first dimension and shape shall pass, characterized in that said draw roll housing also includes a first through penetrating, radially extending, round hole which is displaced in a first direction so that an edge on said first hole will coincide generally with a first draw roll housing diameter ; and in that the draw roll housing includes a second throughpenetrating, radially extending, round hole which is displaced in a second direction generally opposite to said first direction such that an edge on said first hole will coincide generally with said first draw roll housing diameter. |
| 16. | A draw roll housing according to claim 14, wherein said housing includes said third throughpenetrating, radially extending, round hole which is displaced in a third WO 2005/021176 PCT/SE2004/001257 direction so that an edge on said third hole will coincide generally with a second draw roll housing diameter ; wherein the draw roll housing also includes a fourth throughpenetrating, radially extending, round hole which is displaced in a fourth direction which is generally opposite to said second direction, such that an edge on said first hole will coincide generally with the second draw roll housing diameter; and wherein said first and second diameters are generally at right angles to each other. |
| 17. | A roll for rolling wire material in a draw roll housing according to claim 11, characterized in that said roll includes a first slide part, a profiled part, and a second slide part as seen in its axial direction. |
| 18. | A wire drawing arrangement comprising a first wire working station in which the diameter and/or shape of a wire or wire blank is worked from a first diameter and/or shape to a second diameter and/or shape; at least one second wire working station in which said wire is worked to bring said second diameter and/or shape to a third diameter and/or shape; and wherein said arrangement also includes means for moving said wire from said. first wire working station to said at least second wire working station such that different parts of said wire will be worked simultaneously and said at least second wire working stations characterized in that at least one of said first and at least second wire drawing stations includes an arrangement according to any one of claims 1 to 16. |
BACKGROUND OF THE INVENTION The most common technique used in the manufacture of wire is to draw a wire blank or rod through a wire drawing machine.
The machine comprises draw blocks that include a number of draw plates which have inlets or dies of respectively decreasing diameters. The wire entering the inlet of a draw plate housing has a slightly larger diameter than the diameter of the inlet. As the wire rod passes through the draw block, it undergoes a reduction in area, which is accompanied by elongation of the wire rod. This technique functions well in practice and a large number of wire drawing machines are commercially available.
One serious drawback with draw plate drawing of wire or a wire blank resides in the high friction generated between wire and draw plate. This frictional force acts along the full length of contact in a direction opposite to the direction in which the wire rod or wire is drawn. Draw plate drawing results in a product that has good tolerances. The high friction generated, however, limits the rate at which the wire can be drawn and also results in a relatively high degree of tool wear.
A reduction in the area of wire can also be achieved with the aid of rolls. Rolling affords a number of advantages over wire
WO 2005/021176 PCT/SE2004/001257 drawing. For example, less power is consumed with wire rolling processes, since drawing of wire takes place while generating significant friction whereas, of course, rolling takes place while generating roller friction-which is not as great as drawing friction. Moreover, rolled wire has a number of material properties that can be beneficial in certain contexts. A greater reduction in area can also be achieved when rolling wire.
A novel tool for cold working of wire, called roller-dies, was developed in Japan at the beginning of the 1960's, wherewith the frictional conditions were much more favourable than in the case of conventional draw plate drawing. This tool comprises two pairs of calibrated idler rollers disposed at 90 degrees in relation to one another.
In this specification, the method of drawing wire through idling rolls is designated draw rolling.
In the majority of cases part of the frictional force generated in draw rolling lies in the drawing direction as opposed to draw plate drawing with which the whole of the frictional force acts opposite to the direction in which the rod is drawn. In the case of draw rolling of wire, or a wire billet or blank, this can be explained by defining, when appropriate, a mutual plane with the properties that the shear stresses caused by friction are directed in opposite directions on respective sides of the mutual plane. In the case of draw plate drawing, the shear stresses are directed in one and the same direction along the full length of the contact between wire and draw plate. Practical studies have shown that the draw rolling technique has, among other things, the following advantages over the draw plate drawing of wire: The possibility of achieving higher rod drawing speeds
WO 2005/021176 PCT/SE2004/001257 The possibility of obtaining a greater reduction in area with each pass The possibility of obtaining a higher total reduction in area prior to annealing The possibility of requiring less complex cooling and lubricating agents and their applications The possibility of modifying the temperature (attemperation) of the cooling agent and lubricating agent and therewith enable constant working conditions to be achieved, resulting in quality enhancing effects.
Despite the advantages shown to be afforded by the novel technique the draw rolling technique has still not found success industrially.
This lack of success is primarily due to the construction weaknesses exhibited by the commercially available units. The original Japanese units have presented primarily serious problems with regard to setting the positions of the rollers, both vertically and horizontally. In some cases, problems have been encountered by the oval profile of a roll striving to rotate before entering the round profiled groove of a subsequent. This can result in fin-like formations that give a pronounced ovality to the drawn rod among other things.
It is also difficult to roll slender wires, and the integration of existing roller-die tools (RD-tools) in existing wire rolling machines is encumbered with high investment costs, due to the space-requiring construction of such machines.
WO 2005/021176 PCT/SE2004/001257 Known RD-tools can thus present problems with regard to the stability of shafts and bearings, resulting in quality problems and production problems and expensive service requirements.
SUMMARY OF THE PRESENT INVENTION The primary object of the present invention is to provide an arrangement, draw plate and rolls, for the cold working of wire with which the aforesaid problems are overcome or at least alleviated.
The present invention includes a typical draw plate housing in which two roll shafts are mounted. The roll shafts each have an appropriate profile, e. g. an oval profile or a round profile, and the wire is rolled through the housing. The rolls are idling rolls and the wire is drawn through the rolls, although in the absence of any contact with the housing. The present invention does not include bearings or shafts typical with known wire rolls and achieves good stability. The arrangement is such as to enable it to be fitted to existing wire drawing machines, therewith adding a new dimension to such machines, namely a wire rolled dimension. In accordance with requirements, the wire can either be rolled, in which case there is fitted a draw roll housing in accordance with the present invention, or drawn, in which case a typical draw plate is fitted to the wire drawing machine.
The draw roll housing is conveniently comprised of a hard, wear resistant material, such as hardmetal, whereas the rolls are made of a tougher, less wear resistant material. The rolls are subjected to wear and can be replaced. The machine operator can thus impart a desired shape to the wire, by
WO 2005/021176 PCT/SE2004/001257 changing rolls of one profiled shape for rolls of another profiled shape.
A particular object of the present invention is to provide a method and an apparatus with which an operator is able to choose whether a wire shall be rolled or drawn in a draw bench.
According to a first aspect of the invention, the aforesaid objects are achieved with the aid of a wire manufacturing arrangement that comprises a housing which includes an inlet for the infeed of metal wire having a first diameter and shape, and an outlet for the outfeed of said wire after working said diameter and/or shape, said housing being designed to enable it to be fitted to a wire drawing arrangement. The housing includes a first and a second hole, or profiled outlet, adapted to accommodate a first and a second roll. The first roll has a first profile and the second roll has a second profile. The first and the second rolls are intended to work the metal wire therebetween such as to change the diameter and the shape of the wire in pattern of said first and said second profiles.
According to a second aspect of the invention, the aforesaid objects are achieved with a wire manufacturing draw plate. The draw plate is cylindrical in shape and includes a through- penetrating central, axial, opening, through which wire of a first dimension and shape can run. The draw plate also includes a first through-penetrating, radial and round hole which is displaced in a first direction so that an edge of said first hole will coincide essentially with a diameter on said draw plate, and a second through-penetrating, radial and round hole which is displaced in a second direction essentially opposite said first direction, so that an edge of
WO 2005/021176 PCT/SE2004/001257 said first-hole will coincide essentially with said draw plate diameter.
Because the housing is designed to enable it to be fitted to a wire drawing arrangement, the function of rolling wire can be added to said arrangement. This means that an operator can choose either to draw the wire or to roll said rod. The fact of the matter is that the operator can choose to roll the wire in certain blocks or rod working stations and then to draw the wire in subsequent blocks, or rod working stations, in one and the same wire drawing arrangement. According to one application, a first block may include two rolls having a first profiled shape and a second block can include two rolls having a second profiled shape. The arrangement also enables rolls to be readily exchanged. This enables different profiled rolls to be used in accordance with the purpose of the rolling operation.
According to one preferred embodiment of the invention, the housing has the same design as a traditional wire drawing plate and is adapted to enable it to be fitted to a wire drawing bench.
The first and the second roll may have mutually different types of. profiles. For instance, the first roll may be oval and the second roll round, or both rolls may have a round or an oval profile. Other types of profiles are conceivable.
According to one preferred embodiment of the present invention, the housing is cylindrical and has a through- penetrating central and axially positioned transit. The transit includes an inlet through which the wire runs into the housing and an outlet through which the worked wire, or wire, exits.
WO 2005/021176 PCT/SE2004/001257 The housing also includes a first through-penetrating, radially extending round hole which is displaced in a first direction so that an axial edge of the barrel surface of said first hole will coincide essentially with a housing diameter.
The housing also includes a second through-penetrating, radially extending round hole which is displaced in a second direction generally opposite to said first direction, so that an axial edge on the barrel surface of said first hole will coincide essentially with said housing diameter.
This arrangement enables the rolls to be arranged in the housing so that the wire or wire will be drawn through the housing in the absence of any contact with said housing itself, and rolled by the rolls disposed in said first and said second holes.
According to one preferred embodiment of the invention, the arrangement also includes first and second cylindrical rolls which are disposed in a respective first hole and respective second hole, wherein said cylindrical rolls include axially a first slide part, a profiled part, and a second slide part.
The first and the second slide parts are intended to abut and slide against parts of the inner barrel surfaces of said holes and respective slide parts of an opposing roll.
As the wire is drawn through the inlet, the rod is pressed against the profiled parts of the rolls which, in turn, press the slide parts against respective inner barrel surfaces in the holes. The rolls are therewith allowed to rotate as the wire is drawn-in and therewith work the wire. The first and the second roll are disposed in the housing so that the profiled parts of said rolls will coincide with said transit
WO 2005/021176 PCT/SE2004/001257 seen in an axial direction. These profiled parts therewith co act to form a common wire working profile.
According to one preferred embodiment of the invention, the arrangement includes a housing cooling means and a lubricating means for delivering lubricant to the slide bearings between the rolls and the inner barrel surfaces in said holes. The cooling and lubricating agents used may conveniently consist of one and the same fluid.
According to one preferred embodiment of the invention, the housing meets the standard ISO 1684.
According to one preferred embodiment of the invention, the housing is comprised of hardmetal (sintered tungsten carbide), and the rolls are comprised of a some what softer hard metal.
Alternatively, the housing may be comprised of some other hard material, for instance from a ceramic material or a diamond material.
In this arrangement, the rolls will be the first to wear. The rolls are relatively cheap and can be readily replaced and therewith constitute a wear part.
According to one embodiment of the invention, the rolls may be mounted in said holes, e. g. with the aid of ball bearings or something other bearing type. Such a bearing may be particularly suitable when the profiled rolls are placed vertically.
One advantage afforded by the present invention is that wire can be both drawn and rolled in one and the same drawing bench. Another advantage is that the rolls can be easily exchanged when worn or when other profiled shapes are
WO 2005/021176 PCT/SE2004/001257 required. The housing itself can also be replaced in a wire drawing station, from a housing for draw plate drawing of wire to a housing for draw rolling of wire. This enables the advantages afforded by draw rolling to be combined selectively with the advantages afforded by conventional draw plate drawing of wire in the absence of the drawbacks associated with respective methods. Another important advantage is that draw rolling can be applied in existing wire drawing arrangements that have earlier been restricted to wire drawing with the aid of draw plates.
Another advantage afforded by the present invention that the problems associated with wire rolling in accordance with the present standpoint of techniques have been avoided. For example, it is no longer necessary to effect sensitive calibration of the rolls.
Further properties of the invention and the advantages associated therewith will be apparent from the following detailed description of embodiments according to the invention.
BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be more readily understood from the' detailed description of preferred embodiments of the invention as given hereinafter and from the accompanying figures 1 to 6 which are intended solely to illustrate the preferred embodiments and shall not be considered limitational with regard to the scope of the present invention.
Figure 1 is a perspective illustration of a wire drawing arrangement according to the present standpoint of techniques.
WO 2005/021176 PCT/SE2004/001257 Figure 2 is a perspective illustration of a drawing roll housing according to one preferred embodiment of the present invention for rolling wire.
Figure 3 is a front view of the housing shown in figure 2 with obscured parts noted in broken lines.
Figure 4 is a side view of the housing shown in figure 2.
Figure 5 is a cross-sectional view of the housing shown in figure 4, taken on the line A-A in said figure and showing the rolls.
Figure 6 illustrates a preferred embodiment of an inventive wire drawing arrangement that includes three blocks, wire drawing stations.
Figures 7a and 7b are perspective views of a draw roll housing according to a further embodiment of the invention, wherein the housing is shown to accommodate two generally orthogonal roll pairs.
Figure 7c is a cross-sectional view of the housing shown in figure 7a and 7b, taken from above.
Figure 8 is a cross-sectional view of the housing shown in figure 7a, 7c taken from one side.
Description of preferred embodiments The following description includes details of specific techniques and applications, so that a sound understanding of the present invention can be obtained. However, it will be understood by the person of normal skill in this art that the
WO 2005/021176 PCT/SE2004/001257 present invention can be practised in embodiments that differ from those described in detail in this text. In other cases, detailed descriptions of well known methods and apparatus have been excluded so as not to obscure the description of the present invention with unnecessary details.
Figure 1 is a schematic illustration of a wire drawing arrangement according to the present standpoint of techniques.
Wire 101 is drawn through a lubricant container 102 containing lubricant 103. The lubricant may be a soap powder, so-called dry drawing, or some form of oil, so-called wet drawing.
The wire is drawn through a draw plate 104 disposed in a cooling device 105, in the illustrated case a water-containing cooling tank. The water is pumped into the cooling device 105 through an inlet 106 and exits from the device through an outlet 107.
The draw plate 104 has a cone angle of between 10 and 25 degrees and, according to the present standpoint of techniques, comprises four parts-an input cone, draw cone, carrier and outlet cone. The inlet cone, or taper, improves the ability to adequately lubricate the wire blank during its deformation. The draw cone forms the actual reduction tool.
The carrier increases the length of life of the draw plate and acts to stabilise the process. The outlet cone increases the mechanical strength of the draw plate and provides a soft or gentle transition as the blank, wire or wire leaves the plate.
The draw plate 104 may be removed from the cooling device 105 when the wire manufacturing arrangement is not in use, and possibly replaced.
Figure 2 is a perspective, diagrammatic illustration of a wire rolling draw plate or housing 201, also referred to as a draw
WO 2005/021176 PCT/SE2004/001257 roll housing in accordance with one embodiment of the invention, in order to distinguish the housing from a wire manufacturing draw plate according to the present standpoint of techniques. The external configuration and appearance of the draw roll housing 201 is the same as that of the draw plate 104 described with reference to figure 1 and therewith fits into the cooling device 105. In other words, the draw plate 104 for wire drawing and the draw roll housing 201 that includes rolls for wire rolling are exchangeable in the arrangement described with reference to figure 1.
When a draw roll housing 201 is used in the arrangement shown in figure 1, the lubricant will lubricate the slide bearings between the rolls and the housing.
The draw roll housing 201 is cylindrical and includes a barrel surface 202, a front side 203 and a rear side 204. The front side 203 has an inlet 204 through which the wire is fed into the housing. Distinct from the draw plates according to the known standpoint of techniques, the opening of the inlet 205 is larger than the diameter of the incoming wire or wire. In other words, the actual housing 201 has no working effect on the. rod or wire, such working being effected solely by the rolls.
The rolled wire exits through an outlet on the rear side 204 of the housing (said outlet not being shown in figure 2). The housing also includes a first hole 206 and a second hole 207, which extend in a radial direction. The holes are displaced radially so that an imaginary inner barrel surface of each hole will coincide generally with a diameter of the draw roll housing 201.
WO 2005/021176 PCT/SE2004/001257 Figure 3 is a front view of the draw roll housing 201, with obstructed parts shadowed by a first roll 301 and a second roll 302 mounted in the housing 201. The wire fed into the inlet 205 is worked by the first roll 301 and the second roll 302 respectively in accordance with the mutually co-acting profiles, clearly seen in figure 3. The first roll 301 has an oval profile 303 and the second roll has a round profile 304.
Figure 4 is a side view of the draw roll housing 201, from which the inlet 205 and an outlet 401 are clearly seen.
Figure 5'is a cross-sectional view of the draw roll housing 201 of figure 4, taken on the line A-A. The first roll 301 consists in a first slide part 501, a profiled part 502 and a second slide part 503. The second roll 302 consists in a first slide part 504, a profiled part 505 and a second slide 506.
The first and second slide parts 501 and 503 of the first roll 301 co-act with the inner barrel surface 507 of the first hole 206, and the first and second slide surfaces 504 and 506 respectively of the second roll 302 co-act with the inner barrel surface 508 of the second hole 207. The profiled part 502 of the first roll 301 co-acts with the profiled part 505 of the second roll 301 and also with the wire, such as to form a roll pair that works the wire into a desired shape and size as it is drawn through the roll pair. According to the invention, the draw roll housing functions solely as a support for the rolls and does not work the rod. In fact, the wire controls, or guides, the rolls, which do not therefore need to be fixed axially.
Figure 6 illustrates a wire drawing machine according to a preferred embodiment of the invention. The illustrated machine includes a first wire working station 601, a second wire
WO 2005/021176 PCT/SE2004/001257 working station 602 and a third wire working station 603. Wire 604, or a wire blank, is fed from a feeder (not shown). The wire or blank is worked in the first and the second wire working station 601 and 602 respectively by means of a draw roll housing in accordance with the invention, therewith enabling a greater reduction in diameter or in cross-section to be achieved than that achieved with draw plate drawing. The wire or blank is rolled in the first station 601 to an oval cross-sectional shape and then to a round cross-sectional shape in the second station 602. At the third station, the wire or wire may be so slender as to prefer drawing with the aid of a draw plate. Accordingly, a typical draw plate can be chosen for the last station 603.
Figures 7a, 7b and 7c each show a respective view of a draw roll housing 703 according to a preferred embodiment of the invention, wherein an additional roll pair is used. In other words, the draw roll housing 703 according to the embodiment shown in figures 7a and 7b includes two'roll pairs which are arranged in an orthogonal relationship to one another. An inlet 701 to the draw roll housing 703 is adapted to receive wire that is to be rolled and fed out through an outlet 702.
The draw roll housing 703 is disposed in a cooling device 704.
As will clearly be seen from the figures, the housing 703 includes. first and second holes 705 and 706 respectively, and third and fourth holes 707 and 708 respectively. The first, second, third and fourth hole 705,706, 707 and 708 are adapted to accommodate first, second, third and fourth rolls (not shown). The first and the second hole 705 and 706 are oval and extend radially and are displaced in two mutually opposite directions, so that respective barrel surfaces will coincide with a first diameter of the draw roll housing. The third and the fourth hole 705 and 706 are also oval and extend radially, and are displaced in two mutually opposite
WO 2005/021176 PCT/SE2004/001257 directions so that respective barrel surfaces will coincide with a second diameter of the draw roll housing, this second diameter being generally at right angles to the first diameter. This enables two rolling passes to be carried out immediately after one another, in two perpendicular directions.
Figure 8 is a cross-sectional view of the draw roll housing in the embodiment described with reference to figures 7a, 7b and 7c respectively. Similar components have been identified with the same reference numerals. A first roll 801 is mounted in the first hole 705, and second roll 802 is mounted in the second hole 706. A third roll 803 is mounted in the third hole 707. Although not evident from figure 8, it will be understood that a fourth roll is mounted in the fourth hole 708.
It may be convenient for the draw roll housings to be designed to provide an arrangement with one or more indexing positions.
Such a design is conceivable in view of any upsetting problems that may occur as the oval rod or wire enters the rolls to be brought to a round cross section, and therewith enable a form of pre-stressed wire line to be obtained. This can be achieved, for instance, by providing the end-walls of the draw roll housings or barrel surfaces with mutually c-acting tooth-like projections.
It will be understood that the invention is not limited to what has been described and that variations and modifications can be made. For example, a wire drawing plant can include more than three working stations, a typical number of stations being between 3 and 8. Such modifications or variations shall not be considered as departing from the scope of the present invention. All such modifications that are obvious to the person skilled in this art are included in the scope of the accompanying claims.