BLASTING APPARATUS AND METHOD FOR TREATMENT OF AN ELONGATE MEMBER

The invention relates to an apparatus, method and various novel apparatus components for treatment, such as shot blasting and/or polishing of an elongate member, such as a rod, wire, pipe, strip or the like.

Conventionally, rod for use in the wire industry is prepared for subsequent wire drawing by mechanical descaling or acid pickling to remove rust, and other surface roughness or contaminants. Typically, low grade steel rod is descaled and high grade steel rod is treated with acid. Following descaling or acid treatment, the rod surface is typically coated with borax, phosphate or lime. The cost of treating steel rod in this way prior to use in the manufacture of wire is not only expensive but can be environmentally hazardous. The chemicals used in treating the rod, particularly in acid pickling, often contain substances which may be a hazard to the environment. The disposal of these chemicals once the treatment process is completed presents a problem especially given the bulk and potential hazard of the chemicals.

Several years ago, shot blasting was proposed as a method of treating rod which is typically made from high carbon, low carbon or stainless steel. In this process

shot or pellets of steel are projected at high speeds against the rod. The conventional shot blasting apparatuses that have been used to date have a number of problems and disadvantages associated therewith.

Several prior art arrangements are illustrated in figures 1 to 4. In figure 1, a conventional shot blasting apparatus 1 comprises a wheel 2 which rotates about an axis 3 in order to project shot 6 towards a rod 4. As can be seen from the figure, the shot stream 6 diverges on leaving wheel 2 and is therefore not concentrated on impact with rod 4. Furthermore, rod 4 is only treated by shot blasting on one side and must be passed through a second apparatus to provide for overall treatment coverage. Also, the shot 6 impacts on the wall 5 of the shot blasting apparatus 1 behind rod 6. The majority of the shot constituting the shot stream 6 does not impact the wire 4. Accordingly, the wall is continually damaged by the impact of the shot.

In figure 2a, a cross sectional side view of a further prior art apparatus is illustrated. Here, guides 7 are provided to limit the dispersion of shot 6 on leaving wheel 2. Thus, there is an improvement in the amount of shot which impacts the rod 4. Figure 2b shows an end view of the apparatus as seen along line AA' in figure 2a. As shot 6 passes along guides 7, it impacts against guides 7 thus peening the innermost surfaces 8 of

guides 7. After a time, innermost surfaces 8 of guides 7 swell and become rounded as illustrated by the dotted line. Therefore, rather than directing shot 6 towards rod 4, surfaces 8 positively direct shot 6 away from rod 4 effectively reduce the efficiency of the apparatus. Wheel blades, especially long wheel blades, are also subject to wear and deformation, for example, from peening. Thus again, the shot may no longer be accurately directed by the blade towards the rod 4.

Thus, shot blasting apparatuses are not only inefficient in their use of shot but also require high maintenance and frequent repair or replacement which results in long down times.

A further problem is the spread of shot sizes as seen in figure 3 wherein a side view of a shot blasting apparatus is shown. The ideal angle of impact of shot 6 against the rod 4 is 90°, that is, the rod 4 and the path of the shot should be preferably perpendicular. For a given speed of rotation of wheel 2 about axis 3, shot is dispersed over a range of angles depending upon its mass. As will be understood by those skilled in the art, shot used in shot blasting is recycled and therefore after a certain number of impacts the average shot size will decrease and it will become lighter which serves to maintain a spread in shot delivery angles. Adding new, heavier shot will increase the average size but will also

provide a greater range of sizes of shot having a corresponding range of dispersement along the wire and an uncontrolled rod surface coverage.

Increasing the blade motor power is important as the shot decreases in mass in order to provide and maintain the necessary momentum of the shot as the mass thereof varies during use. The momentum of the shot affects the influence of the impact of the shot on the rod. However, the maintenance requirements on the blade motor also increase with increased rotational speed. In addition, whilst providing the lighter shot with the necessary force of impact, the increased motor power increases the overall angle of spread of shot, again providing an uncontrolled rod surface coverage. Indeed, the rod travels from a region where it is impacted by heavy shot to a region where it is impacted by light shot.

The rod, which may be around 5.5mm to 13mm or even up to 25mm in diameter, is paid-off from a coil. Pay-off from a static coil results in rod torsion so that the rod is not straight and its passage through the apparatus may not be wholly axial again resulting in uncontrolled coverage of the rod surface by the shot particularly in in-line apparatuses (shot blaster apparatus in-line with a drawing apparatus) .

The distance of the wheel to the rod in conventional apparatuses is usually around 60cm requiring increased motor power to provide the necessary impact and/or direction of shot.

Turning now to figures 4a and 4b, a prior art arrangement of another shot blasting apparatus containing three wheels 2a, 2b and 2c is shown. Figure 4a is a side view and figure 4b is an end view. The three wheels are typically located substantially facing one another and positioned approximately 60 cm from the rod 4. Whilst this improved apparatus arranges for shot to be directed towards all sides of the rod, each wheel may also be subject to shot blasting from the two facing wheels and therefore may suffer excessive wear.

Thus, known shot blasting apparatuses result in non- concentrated shot impact on the rod, excessive wear and destructive impact of shot on the shot blaster housing and other components, inconsistent shot blasting of the surface and therefore inconsistent rod cleaning (blind spots), shot binding when the wheels or turbines are in the same plane, deformation of wheel blades and shot guides by wear and peening and uncontrolled rod surface coverage.

Furthermore, conventional shot blasting apparatuses also have down times approaching 50% and are not

particularly adapted to drawing wire in a drawing apparatus which is a continuous operation. Using known apparatuses, shot blasting at present is a stop-start process requiring frequent maintenance and replacement of parts.

It is an object of the invention to reduce and substantially eliminate at least some of the above problems of the prior art.

According to one aspect of the invention there is therefore provided an apparatus for treatment, such as shot blasting or polishing, of an elongate member, such as a rod, pipe, strip or the like, having a longitudinal axis, said apparatus comprising: a first rotatable delivery means positionable relative to elongate member and being arranged to project a treatment medium so as to impact the elongate member, wherein the distance between the rotatable delivery means and the elongate member is approximately 150mm or less. Preferably, the distance is around 50 millimetres or less.

In a preferred embodiment, means for drawing the elongate member through the apparatus are provided.

Preferably a separate drawing apparatus is positioned adjacent the apparatus of the invention for drawing the

elongate member through the apparatus of the invention, and, preferably for drawing the rod into wire.

The first rotatable delivery means situated proximal to the elongate member, such as wire, rod or the like, advantageously improves the efficacy with which the apparatus can clean such members.

It will be appreciated that the first rotatable delivery means may comprise a single wheel suitably positioned with respect to the wire or rod.

However, having a single delivery wheel limits the coverage of the treatment process. Accordingly, an embodiment provides an apparatus for the treatment of an elongate member further comprising a second rotatable delivery means, said first and second rotatable delivery means forming a first pair of rotatable delivery means, wherein the first and second rotatable delivery means are disposable on substantially opposite sides of the elongate member.

Prior art apparatuses, such as those depicted in figure 4B in which the axes of rotation are all co-planar incur damage due to shot from the opposing wheels.

Suitably, an embodiment provides an apparatus for treatment of an elongate member wherein the first and

second rotatable delivery means are longitudinally offset by a predetermined distance relative to each other.

The longitudinal disposition or separation of the wheels, ie the pair of rotatable delivery means, obviates or reduces the possibility of damage being sustained by a wheel due to errant shot from an opposing wheel. It will be appreciated that the advantages of offset delivery means follow regardless of the distance of those means from the elongate member. However, the preferred distance is less than 150mm.

Preferably, an aspect of the present invention provides an apparatus further comprising a second pair of rotatable delivery means, the second pair of rotatable delivery means being longitudinally spaced apart from the first pair of rotatable delivery means.

In order to improve coverage of the treatment process, an embodiment provides an apparatus further comprising a second pair of rotatable delivery means, the second pair of rotatable delivery means being longitudinally spaced apart from the first pair of rotatable delivery means. In order to provide a compromise between the degree of coverage of the treatment process and the volume of space required to house an apparatus according to an embodiment, an apparatus is provided in which the first and second pairs

of rotatable delivery means rotate in respective first and second planes which longitudinally intersect the elongate member.

A preferred embodiment provides an apparatus for treatment of an elongate member wherein the or any of rotatable delivery means is selectably rotatable in at least one of either an anticlockwise direction or a clockwise direction.

Advantageously, the wheels or rotatable delivery means can be rotated in either a clockwise direction or an anticlockwise direction. Preferably, the rotatable delivery means is reversibly rotatable.

A further aspect of the present invention provides an apparatus for treatment of an elongate member wherein the rotatable delivery means comprises at least one blade having a first delivery surface.

In order to facilitate repair of the apparatus said blade is detachably couplable to the rotatable delivery means.

As mentioned previously, the replacement of blades in such apparatuses is expensive. Suitably, an embodiment provides an apparatus wherein said blade further comprises a second delivery surface,

substantially similar to said first delivery surface, disposed on an opposite side of said blade to said first delivery surface. In a preferred embodiment said blade is adapted to be reversible such that either of said first or second delivery surfaces can be used for projecting treatment medium.

As the elongate member may be narrow relative to the width of the blades, an aspect of the invention provides an apparatus wherein said first delivery surface is profiled so as to focus the treatment medium towards to the elongate member. Preferably, at least the central portion of a blade is concaved.

In a preferred embodiment, the apparatus comprises four wheels which are, preferably, spaced along the elongate member, and also preferably, alternating above and below the rod.

In a preferred embodiment the wheels are substantially equidistant and/or of substantially the same diameter.

Preferably, the wheels are arranged in pairs and the wheels within each pair are positioned such that the plane of rotation of one wheel is substantially in line with the plane of rotation of the other wheel. The plane of one pair of wheels is angled through, preferably,

approximately 120° with respect to the next pair of wheels. Within a pair, the wheels are spaced along the centreline of travel of the rod by a distance roughly equal to the diameter of one wheel. From one pair to the next, the wheels are separated by a distance along the wire of approximately three times the longitudinal separation of the wheels in a pair.

Each wheel may comprise one or more blades and preferably comprises several blades arranged approximately equidistantly around its axis of rotation.

The blades are preferably aligned along the radii of the wheel. Each blade may have a profiled delivery surface.

In cross section the surface is preferably concave so as to focus treatment medium such as shot against the elongate member as it passed adjacent to the delivery means. A preferred blade profile is illustrated in figure 12.

In a preferred embodiment, guide means are provided to limit the spread of the media in either the vertical and/or horizontal direction.

In a further preferred embodiment, collection means are provided to collect upwardly and/or downwardly directed treatment media. The means for collecting upwardly directed media may be magnetic.

In a preferred embodiment, the timing and/or delivery location of the treatment medium, such as shot, can be controlled by means of a variable position and/or variable sized window through which the shot must pass prior to delivery to the delivery surface of a blade and subsequent delivery to the elongate member. The window may be used to control the timing and/or duration of shot delivery.

In a preferred embodiment, the wheels are located in pairs each within a housing having a hinged lid. Preferably, means for adjusting the variable position and/or variable sized window are located in the hinged lid of the housing.

Other aspects of the present invention and embodiments thereof are set out in the appended claims.

Preferred embodiments of the invention will now be described, by way of example only, with reference to and/or as illustrated in the accompanying figures.

Figure 5 shows a side view of a schematic shot blasting apparatus according to an embodiment of the invention with four wheels, illustrating the position of the wheels with respect to each other and the rod 4 passing through the apparatus.

Figure 6 is an end view seen along rod 4 of the schematic shot blasting apparatus of figure 5 illustrating the radial position of the wheels with respect to the rod centre line.

Figure 7 is a more detailed schematic side view of a shot blasting apparatus in accordance with the invention.

Figure 8 is a view taken along the rod centre line in cross section of an apparatus in accordance with the invention illustrating the position of guide plates with respect to the direction of travel of the rod.

Figure 9A is an end view of the apparatus seen in figure 7 along the direction of arrow 100. Figure 9B is an end view of the apparatus in figure 7 seen along the direction of arrow 110.

Figure 10 is a cross sectional close-up of a wheel and the guide plates seen along the direction of travel of rod 4.

Figure 11 shows elevation, cross section and end views of a preferred blade in accordance with the invention.

Figure 12 shows an end view of a further preferred blade in accordance with the invention.

Figure 13A shows a schematic end view of an apparatus in accordance with the invention illustrating the arrangement of apparatus housings. Figure 13B is a schematic top view of the apparatus in accordance with the invention illustrating the location of the wheels with respect to the apparatus housings. Figures 13C and 13D illustrate more detailed end and top views of a similar apparatus to that seen in Figures 13A and 13B.

It will be appreciated that the embodiment described above comprises an apparatus for treatment of an elongate member wherein the housings are inclined relative to one another. Preferably, the angle of inclination of the housings relative to one another or relative to any other convenient frame of reference is variable and can be set at an arbitrarily selectable.

Preferably, the width of the housings is only slightly greater than the width of the turbines for projecting the treatment medium towards the wire to be treated.

Figure 14 is a side view of a housing of an apparatus in accordance with the invention illustrating the location of the hinges on the lid.

Figure 15 is a cross sectional view of the lid seen in figure 14 illustrating the mechanism for opening the lid using a pneumatic cylinder and the location of control cages for adjusting the timing and/or location of delivery of shot to a blade prior to directing same towards the rod to be treated.

Referring now to figure 5, a shot blasting apparatus 10 having rotatable delivery means comprising wheels 11, 12, 13 and 14 for delivering shot towards a rod 4 is illustrated. The direction of travel of rod 4 through apparatus 10 is indicated by the arrow. Rod 4 is pulled through apparatus 10 by an adjacent wire drawing apparatus (not shown). Wheels 11, 12, 13 and 14 rotate about respective axes 15, 16, 17, and 18 respectively. Shot is delivered to the wheels and, as the wheels rotate, the shot is delivered to rod 4 as it passes adjacent to the wheels. The wheels are staggered on either side of rod 4. In particular, wheels 11 and 12 are longitudinally spaced by a distance d. Optionally, spaced further along the line of travel of rod 4, wheels 13 and 14 are provided which are also spaced by a distance d. The separation of the first pair of wheels from the second pair of wheels is approximately three times the distance between the wheels constituting a pair, that is 3d.

Although an embodiment has been described above in which the rotatable delivery means comprises four wheels, a further embodiment may comprise only a single wheel, or a pair of wheels.

In the following figures, like referenced numerals refer to previously like referenced features.

The angular relationship of the wheels with respect to each other is illustrated in figure 6. Here, wheels 11 and 12 comprise blades IIA, IIB and 12A and 12B respectively. The blades IIA, IIB, 12A and 12B rotate about wheel axes 15 and 16 respectively. As can be seen from figures 5 and 6, although wheels 11 and 12 are spaced along the line of travel of the rod, they rotate in substantially the same plane on opposite sides of rod 4.

Similarly, wheels 13 and 14 comprise blades 13A, 13B and 14A, 14B which rotate about wheel centre lines 17 and 18 respectively. Wheels 13 and 14 rotate in substantially the same plane on opposing sides of rod 4. Thus, rod 4 receives shot from wheels which are radially and longitudinally disposed about the axis of the rod.

The plane in which the first pair of rotatable delivery wheels 11 and 12 rotate is at an angle of approximately 120° to the plane in which the second pair

of rotatable delivery wheels 13 and 14 rotate. This ensures coverage surface substantially the entire surface of rod 4 whilst allowing ease of construction of apparatus 10 and ease of access for replacement and repair of wheels 11 to 14 and associated components. Preferably, the planes containing the pairs of delivery are inclined at or within 30" to a vertical.

Wheels 11 to 14 can be adapted to rotate either clockwise, anticlockwise, or be reversible. Preferably, wheels on opposite sides of the wire in a pair rotate in opposite senses.

Referring now to figure 7, there is partially depicted a more detailed schematic side view of an apparatus in accordance with an embodiment of the invention. Here, wheels 11 and 12 comprise several blades 19 positioned equidistantly about the axes of rotation of the wheels. It is desirable that the distance between the edge of the blades 19 and the longitudinal axis of rod 4 along its direction of travel, the distance being denoted 't', is less than around 150mm and preferably less than around 50mm.

Although an embodiment has been described in which the elongate member to be treated is continuously moving through the apparatus, the present invention is not limited thereto. An embodiment could be realised in

which the elongate member remains stationary within the apparatus. Optionally, the rotatable delivery means may be moveable relative to that stationary member.

A radially extending pair of shot guide plates 21 are provided for guiding shot released from the first pair of wheels 11 and 12 into a collection tray 25 or a magnetic collection chamber 23 respectively. Shaped longitudinally extending treatment medium guide plates 22 also are provided for directing shot towards rod 4 as the rod 4 passes through the apparatus in the direction of travel indicated. The radially extending 21 and longitudinally extending 22 pairs of plates are mutually perpendicular. It will be appreciated that if the plane of the wheels is substantially vertical, as is preferable, the guide plates will also be substantially vertical. However, if the plane of the wheels is substantially horizontal, the radially extending guide plates will still have vertical guide faces whereas the longitudinally extending guide plates will have substantially horizontal guide faces.

Referring now to figure 8, the effect of providing guide plates 21 and 22 is illustrated. Here, a rectangular window 101 is provided by the edges and sides of guide plates 21 and 22 respectively. As can also be seen from the figure the tips of the blades 19 pass in close proximity to the centre line of rod 4.

The guide plates 21 or 22 may be either substantially parallel or may converge slightly to further focus the delivery of the treatment medium, such as shot, to the elongate member.

Referring now to figure 9A, an end view of the apparatus of figure 7 is shown along the direction of arrow 100. Magnetic collection chambers 23 are provided to collect excess shot. The magnet chambers 23 are arranged to retain a sufficient depth of treatment medium so that the impact of subsequently incident shot is absorbed by previously retained shot. Thus, damage to the surrounding housing and the chambers is limited.

Referring now to figure 9B, an end view of the apparatus of figure 7 is illustrated looking in the direction of arrow 110. Here, a shot collection tray 25 having a recess 26 is provided for collecting downwardly directed shot.

It can be seen from the figures that the guide plates 22 not only direct shot towards rod 4 but can also serve to direct excess shot following shot blasting towards shot collection means such as a magnetic chamber 23 or shot collection tray 25.

Referring now to figure 10, a close-up of the apparatus including a cross section of wheel 12 is shown.

Here, wheel 12 comprises a rotating blade carrier 20 which is U-shaped in cross section on which blades 12A are mounted. An impeller 28 having at least one control aperture 28A is fixed to blade carrier 20 with aperture or slot 28A aligned with the blades so that shot is passed from inside impeller 28 out towards blades 12A through aperture 28A when blade carrier 20 and impeller 28 are rotated. A non rotating, variable position control cage 27 is also provided with an opening 27A through which shot must pass. Opening 27A in conjunction with slot 28A may be used to provide a variable position and/or variable sized window through which shot is passed to blade 12A. This means that when the position of control cage 27 is adjusted (means for adjustment not shown) the duration and/or timing of delivery of shot to blade 12A and hence to rod 4 can be controlled. Thus, as the shot becomes lighter during use, it may be released earlier in the rotation of wheel 12 with respect to the rod such that the substantially perpendicular angle of impact of the now lighter shot onto the rod 4 is maintained. Thus, the average angle of impact over the range of sizes shot can be kept close to perpendicular, notwithstanding the variation in shot size during use of the apparatus. Thus, the apparatus is adapted for a more continuous style of operation.

As will be understood by those skilled in the art, providing a series of wheels staggered along and

positioned about the line of travel of the rod also allows for a more continuous style of operation.

Figure 11 shows plan, end and side elevations of a blade 29 provided with a dovetail blade mounting 31 for slotting into a blade carrier (not shown). The recessed profiled surface 30 of the blade is rounded at its inner corners to facilitate direction of the shot towards the central part of the blade and hence, as the rod is aligned with the central part of the blade, towards the rod.

Turning now to figure 12, there is shown a preferred blade 27A having a preferred blade profile 30A. Here, flanges 31A are provided to hold the blade in the wheel. Surface 30A comprises a concave region towards the central portion of the blade. Tests have been carried out to determine the preferred blade profile as illustrated for focusing of shot towards the rod.

As can be seen from figures 11 and 12, blades 29 and 29A are provided with profiled surfaces on both sides. This means that the wheels may readily be used in a reverse direction. This also means that the blades may be simply reversed, or in one embodiment, removed from the wheel, reversed and replaced, and the wheel allowed to rotate in the same direction so that the lifetime of

any given blade is increased two-fold. The blades may also be removable for replacement.

Referring now to figures 13A and 13B, angled housings 32 and 33 containing wheels 11, 12 and 13, 14 respectively are illustrated. Hinges 34 are provided to allow access to the interior of each housing by raising the lids of the housings as shown by the respective arrows. Housings 32 and 33 are of independent construction and are preferably bolted together at a junction 40 to form a unit. When one housing needs to be repaired or replaced, it may simply, where necessary, be unbolted from the adjacent housing. Each housing can therefore be independently replaced or repaired. Figures 13C and 13D show the housings and positions of the wheels in greater detail.

The staggered locations of the wheels beneath the lid 35 is illustrated in figure 14.

The shot blasting apparatus of the invention may be used with rod of several different diameters, however where a greater range of diameters of rod are required, it may be preferably to provide shot blasting apparatuses of different sizes.

Referring now to figure 15, the control cages 27 for adjusting the distribution of shot onto the blades within

a given wheel are located in lid 35. A pneumatic or hydraulic cylinder 36 with an appropriate arm linkage 37 to the lid 35 is used to open and close lid 35.

It will be understood by those skilled in the art that the provision of housings 32 and 33 and hinged lids 35 allows easy access to the interior of the apparatus for maintenance thereof and replacement and repair of the components therein. The provision of guide plates 21 and 22 and collection means 23 and 25 and contoured blades 29 and 29A, as well as the proximity of the blades to the rod 4 reduces the degree of dispersion of shot within the housing and thus protects not only the housing but other components from damage by shot blasting as well as improving the efficacy of the apparatus in treating elongate members such as wires and the like. Indeed, the shot blasting coverage by the first two wheels 11 and 12 may be sufficient such that the remaining two wheels 13 and 14 may be used to deliver a different treatment medium suitable for polishing the rod. Furthermore, the overall location of the wheels with respect to one another improves the overall coverage along the rod particularly when the rod is paid off from a coil and therefore may be subjected to torsion and not be straight.

Other advantages and benefits of the invention will be apparent to those skilled in the art from the

information contained herein. Furthermore, alternative embodiments of the invention will also be apparent to those skilled in the art from the information contained herein. All such alternative embodiments are intended to lie within the scope of this application.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings) , and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.