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Title:
WIRE STRAIGHTENING METHOD
Document Type and Number:
WIPO Patent Application WO/1993/013892
Kind Code:
A1
Abstract:
The invention refers to a method for straightening wire of circular cross-section, which is characterised by the progress of wire through successive circular holes, created either on solid bodies (e.g. plates) (Figures 1a and 1b) or by pairs of cylinders tangential by a straight line parallel to their axes which able to be driven independently, wherein the holes are formed by opening grooves of semicircular cross-section on the surface of the cylinders, in a plane vertical to the cylinders' axes, whilst on the contact line between the two bodies, the circular hole (Figure 2) is formed by the two grooves, wherein the bodies bearing the holes (plates) or the cylinder pairs that form holes at their contact points, execute a circular translational motion (Fig. 1a), on a plane vertical to the direction of the wire advancement, resulting to a cyclic-type bending of the wire at its instantaneous contact point with the circumference of the hole, while the wire advancement is achieved either by an external mechanism in the case of the holes on the plates, or by the coordinated rotation of the cylinder pairs (by an independent mechanism) and the advancement of wire by friction forces on the grooves in the process of the circular translational motion and in the direction of the cylinders' rotation.

Inventors:
Anagnostopoulos, Panagiotis A.
Anagnostopoulos, Antonios P.
Application Number:
PCT/GR1993/000002
Publication Date:
July 22, 1993
Filing Date:
January 20, 1993
Export Citation:
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Assignee:
Anagnostopoulos, Panagiotis A.
Anagnostopoulos, Antonios P.
International Classes:
B21D3/04; B21D3/08; B21F1/02; (IPC1-7): B21F1/02
Foreign References:
GB619463A1949-03-09
US2084746A1937-06-22
FR410237A1910-05-14
DE2059145A11972-12-21
GB1032127A1966-06-08
GB1472024A1977-04-27
GB1466638A1977-03-09
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Claims:
CLAI MS
1. Method for straightening wire of circular crosssection, which is characterised by the progress of wire through successive circular holes, created either on solid bodies (e.g. plates) (Figure la, lb) or by pairs of cylinders tangential by a straight line parallel to their axes which are able to be driven independently, wherein the holes are formed by opening grooves of semicircular crosssection on the surface of the cylinders, in a plane vertical to the cyliners' axes, whilst on the contact line between the two bodies, the circular hole (Figure 2) is formed by the two grooves, wherein the bodies bearing the holes (plates) or the cylinder pairs that form holes at their contact points, execute a circular translational motion (Figure la), on a plane vertical to the direction of the wire advancement, resulting to a cyclictype bending of the wire at its instantaneous contact point with the circumference of the hole, while the wire advancement is achieved either by an external mechanism in the case of the holes on the plates, or by the coordinated rotation of the cylinder pairs (by an independent mechanism) and the advancement of wire by friction forces on the grooves in the process of the circular translational motion and in the direction of the cylinders' rotation.
2. Method, as in Claim 1, wherein more than one bending rings of various internal diameters are secured on each plate moving on a circle and remaining parallel.to itself, for the straightening of more than one wires of different diameters simultaneously.
3. Wire straightening method, as in Claim 1, wherein the translational and at the same time circular motion of the plate, where the bending rings are secured on, is achieved by joining it to two camshafts, which have parallel planes of maximum eccentricity and rotate in phase (Figure 15).
4. Wire straightening method, as in Claτlm 1, wherein the bending plates are joined on the camshafts, as in Claτlm 3, wherein for the adjustment of the eccentricity, the use of cams of rectangular crosssection and two adjustment screws are preferred where the eccentricity is in relation to the rotation axis, which is of rectangual crosssection, having one side equal to the smaller side of the rectangular cross section of the cam (Figure 18).
5. Wire straightening method, as in Claim 1, wherein the successive cylinder pairs bearing semicircular cross section grooves for the formation of holes on the meeting points of the grooves, participate in the main translational circular motion, and they are simultaneously rotated through an independent mechanism, thus advancing the wire by means of friction forces on the points of contact with the grooves.
Description:
WIRE STRAIGHTENING METHOD

The invention refers to a method for straightening wire of circular cross-section, which is characterised by the progress of wire through successive circular holes, created either on solid bodies (e.g. plates) (Figure la, lb) or by pairs of cylinders tangential by a straight line parallel to their axes which are able to be driven independently, wherein the holes are formed by opening grooves of se i- circular cross-section on the surface of the cylinders, in a plane vertical to the cyliners' axes, whilst on the contact line between the two bodies, the circular hole (Figure 2) is formed by the two grooves, wherein the bodies bearing the holes (plates) or the cylinder pairs that form holes at their contact points, execute a circular translational motion (Figure la), on a plane vertical to the direction of the wire advancement, resulting to a cyclic-type bending of the wire at its instantaneous contact point with the circumference of the hole, while the wire advancement is achieved either by an external mechanism in the case of the holes on the plates, or by the coordinated rotation of the cylinder pairs (by an independent mechanism) and the advancement of wire by friction forces on the grooves in the process of the circular translational motion and in the direction of the cylinders' rotation.

STATE OF THE ART

The state of the art contains methods of straightening wire of circular cross-section by passing the wire through straightening rotors. Three methods for the formation of straightening rotors, are stated herebelow:

1. The rotor of Figure (3) includes rods (300), one edge of which (301) touches and presses radially the wire to be straightened (303), during the rotation of the rotor, whilst their other edge (302) is secured on the rotor interior. In the course of the rotor's rotation, the wire is successively

bent by the rod edges (301) and it is finally straightened according to the theory stipulated in paragraph 2 herebelow. 2. In the second method of formation of straightening rotor (Figure 4), the rotor carries interior bushes (406) which rotate along with the rotor body (410) and the wire (405) is forced to pass through those bushes.

The geometrical axes of the bushes (407) are parallel to the rotor rotation axis (409), without coinciding with it, and they are located in a distance from the rotor rotation axis, so that during the rotor's rotation the bushes rotate eccentrically in relation to the rotor axis.

The wire is forced to pass through said bushes in such a way that their eccentric rotation may bend the wire in a cyclic way as in method (1) hereinabove. In the rotating rotor, the wire of diameter d is subject to bendings θi for straightening purposes, equal to the number of bushes (Figure 5) .

The axes of symmetry of the straightening bushes are usually parallel to the rotation axis X-X of rotor and located on a plane (E), which is called wire straightening plane. The straightening plane (E) is rotated, as expected, around the rotation axis X-X of rotor, in the direction of rotation Φ2 and at the same frequency as the rotor. The wire has no rotation Φl around this axis, as it is retained by the coil which is originating from, as well as by reversing rollers for the inward and outward advancement of the wire from the rotor. Moreover, by the action of the said rollers, the wire gains speed ϋ in the direction of axis X-X (Figure 6) .

Careful observation of the point of wire K, where the pressure is applied, by a bush (601), shows that point K on the wire surface forms (by slip) a curve which is proved to be a helix.

Indeed, the wire is fixed against rotation and therefore K

performs a circular motion on the wire surface, forming an angle: σ=2τcnt ...(1) with respect to an initial radius (for t=t o =0)

Simultaneously, performs a motion parallel to the wire axis at a speed U, hence the helix is created by the combination of those two motions.

The respective advancement step on the rotor X-X is: S-Ut -..(2)

If σ=2τc, then S equals to the step B of the helix and from (1) and (2) it is concluded: U=Bn ...(3)

If ζ is the angle formed by the tangent to the helix and axis X-X, it is easily concluded that:

B=τcd/εφζ (4)

That is: tanζ= τcd/B= πdn/U ...(5)

In order to achieve a good straightening it is found that: 50° <ζ< 55° and therefore from (5) it is concluded that a certain relation should exist between n and U in order to accomplish a practically good straightening:

U/n = τcd/tanζ ... (6)

In a variation of the said second formation, the internally mounted bushes, are supported on ball bearings, in order to be able to rotate about their geometrical axis. This way, the contact and friction between the bushes and the wire to one point of the inner bush is avoided and therefore the increased local wear is also avoided.

3. In the course of this formation, rollers of a particular exterior surface type are on the rotor interior, which contacts the wire to be straightened at an angle. The external surface of these rollers is formed by one of the conic sections (ellipse, cycle, hyperbola, parabola, intersected straight lines) by their rotation by 360°

(Figure 7). Thus, during contact of the roller with the wire at an angle, their intersection is a straight line (property of surfaces resulting from rotation, of conic sections). The straightening rollers (801) formed in this way, are secured on the interior of the rotor (802) (Figure 8) with their geometric axis being at an angle in relation to the rotor rotation axis. From this position, they are in contact with the wire at a straight line, and by pressing it they bend it in a radial direction. Thus, the action of the rollers resembles the action of the straightening bushes of the previous formation. Moreover, by this formation, the friction forces between the rollers and the wire to be straightened, also cause the automatic advancement of the wire.

DISADVANTAGES OF THE STATE OF THE ART

The disadvantages of the state of the art are the following:

1. The straightening rotor is driven by an independent motor. This way, the straightening machine becomes very bulky.

2. A complicated manufacturing process for the formation of the straightening rotor's interior is required. The straightening rotor's manufacturing becomes more complicated due to the existence of the systems regulating the position of the bending bushes (or rollers, or rods).

3. The rotation of the rotor results in the development of large inertial forces. It is therefore necessary that the straightening rotor is constructed in a solid and bulky way in order to bear those forces.

4. Due to the rotor's rotation, it is essential that the rotor weight is balanced for smooth rotation. From the above, it is concluded that the rotor's construction is complicated, requires accuracy and, as a result, it is

costly .

5. The said formations result to the wear of the surfaces that come into contact with the wire. The replacement of the worn out surfaces requires the dismantling and re-mantling of the rotor, which requires time, experienced personnel availability and proper spare parts.

6. Great difficulty and bulky construction are required, if the combination of many straightening rotors is desired for straightening several wires simultaneously. Practically, many single straightening machines have to be integrated into one group.

7. The requirement of complicated adjustments of each bush or roller separately, in order to achieve the desired straightening results. Apart from the balancing needs, extremely experienced personnel is required in order to operate such a straightening system.

DISCLOSURE OF THE INVENTION

The novelty of the invention consists of the achievement of the method for the straightening of wire of circular cross- section, by the radial bending as in the state-of-the-art methods, but with the following differences:

1. By cancellation of the rotation of any part (e.g. the rotor) of the straightening mechanism.

2. By cancellation of the assembly, of the bending elements (rods, bushes, rollers), to a complicated mechanism (rotor).

3. By independent motion of the surface of each wire bending element.

4. By replacement of the rotation with the circular translational motion, that is a motion where the body

remains parallel to itself and each point of the body moves on. a circle of constant radius (for all its points) , where the plane of the circle is vertical to the direction o'f the wire advancement. The basis of the whole invention is the solid C (Figure 9a).

Points Σ- and ∑2 of the solid, perform simultaneously circular motions - rotations - around the fixed points A and

B respectively, through the beams ( ) and (β) pivoted at points Σ-i, A, ∑2, B and having the following lengths:

(∑ 1 A) meaning that A∑ 1 ∑2 BA is a rectangle.

Already, any point Σ3 of solid C (Figure 9b) performs a circular motion on the same plane, which is proved by the drawing of straight lines AΓ and BJ7, being respectively parallel to ∑ι 3 and ∑2 3 and by observing that the triangle ATB is equal to the fixed triangle • Then point r is the fixed rotation centre of Σ3 with

If a straightening bush is fitted at point Σ3, whose axis of symmetry is vertical to the plane of body (C), then the result is the construction shown in Figures (10a, 10b), or in case r is small, as it is usually required (e.g. 5 to 10mm), the construction shown in Figures (10c, lOd) is achieved when the solids ( ) and (β) end up to be camshafts, allowing solid C to be supported on both sides, as well as the installation of any number of solids C, placed parallel next to each other.

In order to create the equivalent wire straightening as in Figures (3), (4), (5), (lib), a number of solids C should be considered, which are moved by camshafts, shown at section T-T (Figure 10a). That is, in order to form the "straightening plane" and the same picture, solids C should be encountered along axis X-X, whose angle ω differs by 180° (Figure 9a) . The wire which is until now externally driven

by a pair of rollers, at a speed U and which is submitted to the previously mentioned counter torsion, experiences the same fatigue conditions as in the conventional straightening machines bearing rollers and bushes (Figure lib) .

In Figure (12) , a system that provides the three following capabilities to the machine of the present invention is presented:

1) Capability to nullify the friction at the direction of the wire advancement also.

2 ) Capability to advance the wire without using external means (rollers, grippers etc.).

3) Capability to accomplish a simple-plane straightening, without motion of solid (1) .

In this system, the wire straightening bushes (9) of the solids (1) have been replaced by the holes (18), which are created at the contact line of the semi-circular cross- section grooves (19) of the two cylinders (20) and (21). The bearings (22), (23) and (24), (25) supporting the two cylinders (20) and (21) respectively are located on solid (1) and consequently participate in the motion of the latter.

CHARACTERISTICS AND ADVANTAGES OF THE PRESENT INVENTION

The main differences of the present invention in relation to the state of the art, as well as the characteristics and advantages of the present invention are the following:

1. A great difference of the invention concerns the extensive time for the bushes' replacement due to wear, and it is explained herebelow.

In the application of straightening machines consisting of

rotating rollers and bushes, the wire is always in contact with the same area of the inner surface of the bush and particularly with the area closest to the rotation axis, since it is the wire stable equilibrium position and it does not change with the rotor rotation (Figure 13).

In the straightening machines of the present invention, the wire is not in touch with the same always area of the inner circle surface. The wire is again in contact with the area of the inner surface of the circular holes (Figure 14), which is nearest to the axis X-X of the wire and which is considered to be its stable equilibrium position. However, due to the fact that solid C does not rotate but is rather translated in the same plane, the areas of the circular holes nearest to the axis X-X change in such a way that during one cylcle for solid C, the wire "sweeps" all the inner surface of the circular hole.

This becomes obvious in Figure (14 ) where at the upper position of solid C the wire is in contact with point M2 of the hole interior, whilst at the lower position it is in contact with its diametrically opposite point K- .

Due to the fact that the contact point between wire and hole interior, during a rotation of solids (α) and (β), travels at the interior surface a length iτD (where D is the internal diameter of the straightening ring), and at the external wire surface a legth ltd (where d is the wire diameter), it is concluded that there is a relative slip between the two surfaces under friction, during one rotation (α) and (β) at a length τ(D-d) .

From the above, it is concluded that by reducing the difference (D-d) , through the rotation of the contact point, we may reduce friction to very low levels.

2. Another big difference of the present straightening machine is its capacity to straighten many wires

simultaneously, which may be placed at short distances next to the other. This is achieved by installing many straightening rings (holes) on the same solid C

3. The machine has the capability of straightening many wires of different diameter each.

4. As a result of paragraph (2), only one electrical motor is used.

Moreover, the following may be given as differences or advantages:

5. The volume reduction of the straightening machine in relation to its productivity in tons of wire per hour.

6. The increase of the straightening machine's operation safety, since the moments of inertia and the linear rotor velocities are eliminated.

7. The capability of quick stopping of the moving system of the present invention.

8. As a result of paragraph (1), excessive local overheating of the ting material is avoided, resulting in less wear and longer ring life.

When the system is embodied by means of pairs of cylinders, following advantages are also noted (Figure 12):

9. The capability to reduce and even to eliminate friction in the direction of wire advancement, by the use of two cylinders (20) and (21), where due to their rotation, the cylinders roll on the wire and their contact point with the wire is sliding without friction.

Since, as already mentioned, the friction of contact point K, during its rotation inside ring (9), is proportional to

the product: τc(D-d)=3.14 x (inner diameter of the straightening ring (9) - wire diameter) it is concluded that by reducing the difference (D-d) the straightening rings' (9) wear is reduced to very low levels in relation to wear encountered in the conventional wire straightening machines, consisting of a rotating rotor and fixed straightening bushes.

It is noted that especially when cylinders (20) and (21) are used instead of the straightening rings (9), due to the contact of the wire, at the point K only, the difference (D- d) may be drastically reduced, therefore the only remaining friction due to internal rotation of the contact point K may be reduced.

10. Wire advancement without using any external means (rollers, grippers etc.) is accomplished by the synchronised rotation of the two cylinders (20) and (21). This synchronisation is achieved by the use of the gears (26) and (27) which are attached on the cylinders' axes. The rotation of either of those two axes e.g. axis (28) of cylinder (20), provides the wires thrust due to the pressure exerted on them at point by the cylinders. The rotation of shaft (28) by an externally driven shaft (34) may be achieved by different transmission systems, such as:

a. by the system of Figure (12) , which consists of two spherical joints (29) and (30), two sliding multiple wedges (31) and (32) and an intermediatery shaft (33),

b. by belts,

c. by flexible shafts,

d. by a system of worm-gear.

These embodiments are not shown on the subject figures.

11. The capability of single plane straightening is accomplished by stopping of the rotation of solids (2) and (3) and by the synchronised rotation of cylinders (20) and (21) as already described in the previous paragraph. This way, a conventional single plane straightening is achieved with the following two options:

a. External wire advancement by rollers, grippers etc. b. Synchronised advancement of cylinders (20) and (21), which is the subject of the inventor's patent application number 90600004.7.

DESCRIPTION OF THE MACHINE

At first, the basic straightening machine, which is shown in Figure (15), will be described, and then other embod-Lments of the machine as shown in Figures (16), (17) and (18) will be mentioned.

There is a number of solids (1) which move parallel to themselves and perform a circular plane motion. A number of 5 solids is shown, but it may be any number more than one. The circular motion is achieved by joining them with two camshafts (2) and (3). The opposite located cams of the two shafts (2) and (3), that is (21) with (31), (22) with (32), (23) with (33), (24) with (34), and (25) with (35), have their maximum and minimum eccentricity simmultaneously and they rotate "in phase", that is their rotation angle measured by a certain starting level is the same.

The successive cams of the same shaft (e.g. of number (2), that is (21) with (22), (22) with (23) etc.) have the levels of their maximum eccentricity parallel, but they rotate with "a phase difference" of 180° (that is they are turned by 180° on the same shaft) (Figure 15b).

Camshafts (2) and (3) rotate at the same direction, being in synchronisation through the sprockets (4) and (5) and the

chain (6) . The sprockets are driven by motor (8) through transmission system (7).

Each one of the movable straightening rings (9) is located on each one of the solids (1), whilst the two Tunmovable straightening rings (10) are located on the fixed frame, one being located before the entry point of the wire to the machine and the other being located after the exit point of the wire from the machine. The X-X axis determines the average advancement direction of the wire though the machine and it is the final straight line of the straightened wire. The intersections of the X-X axis with the planes of solids (1) are the centers of rotation of rings' axes (9) during their rotation (11) caused by the motion of solids (1) (Figure 15a).

For each wire two τimmovable straightening rings (10) and a number of movable rings (9) [equal to the number of solids (1)] are required. In Figure (1), only one wire is shown for simplicity. Moreover, the required entrance and exit rollers, which are driving the wire (12) in the direction of X-X, at a speed U, are not shown since those mechanisms are common in all straightening machines.

As it has been already indicated in the general part thereof, the movable (9) and immovable (10) rings are located on the rotating wire straightening plane,, and they achieve the straightening of the wire, which is pulled by the rollers.

The movable rings (9) are easily mounted on the solids (1) by means of grippers (13) (Figure 15a). The geometrical data which are essential to the straightening of wire of a given diameter d, are the following (Figure 15c):

1. The distance 1 between two successive rings (9) [equal to the distance between the successive solids (1)].

2. The length l of the rings (9) or (10).

3. The clearance I2 between the rings (9) or (9) and (10).

4. The interior diameter D of the rings (9) and (10).

5. The eccentricity r of the circular motion of the solids (1).

By an approximate theory, in the case of equal distances 1-^, I2, 1, the following relation is found:

[r-0.5(D-d)] = (K 2 d 2 -0.251 1 2 ) 1 2 - (K 2 d 2 -0.251 2 ) 1 2 (7)

where for a good straightening it should be

17.5 < < 12.5 (8) and U/n = πd/tan (50° ÷ 55°) (9)

(wherein ϋ is the wire advancement speed and n is the frequency of circular motion)

Thus, by mainly changing the rings (9) and (10) (that is l* j _, 12, D) and the advancement speed U, it is possible to adjust a given machine (r, n) to accept a new wire of a different diameter d.

Many facilities are provided in the construction of camshafts (2) and (3) , such as:

a. Construction of one type of cam which creates the eccentricity with phase difference of 180° on a shaft, bearing only one wedge groove (Figure 16), upon its rotation about its symmetry plane ε-ε.

b. Capability to mount a ball-bearing on the external surface of the cam, when implementing the previous method.

c. Capability to increase the length 1-^ of the rings by

the construction Figure (17).

d. Changing of the eccentricity of the cams of the camshafts (2) and (3) by installing cams of rectangular cross-section, and by adjusting them using two screws (Figure 18).

e. Support of the camshafts (2) and (3) only by one bearing, thus presenting those camshafts as clamped beams, resulting in easy changing of the camshafts.

In Figure (19) a variation of the present invention is presented, which uses two pairs of camshafts (2) - (3) and (14) - (15). The solids (1) of one phase are attached to the first of the camshaft pairs and the solids (1) of the other phase to the second of the camshaft pairs. There is, of course, a synchronisation between the shafts of the pairs as already mentioned, as well as a synchronisation between the pairs.

On the said variation of the machine, that is when two pairs of camshafts are used, each pair bearing the solids (1) of one phase, we may easily change the eccentricity r of the rotation. Such an adjustment is shown in Figure (20).

The pairs of the camshafts may rotate either at the same or opposite direction.

In Figure (21), a variation of the machine with four camshafts is shown, wherein the two camshafts (3) and (15) [one of each pair (2) - (3) and (3) - (15)] have been replaced by slide rulers bearing cylindrical joints (16) and (17), respectively.

It is proved that when: p then point Σ (and Σ ) performs approximately circular motion.