Post-forming method and apparatus

Abstract

One aspect of the invention concerns a metallic bar or post (15) comprising a longitudinal axis; a spine (16) extending along the longitudinal axis; and at least three interconnected arms (17-19), each of which extends along the spine (16) and generally radially from the spine (16), with a free end (20-22) of each said arm (17-19) being tapered in the direction of the free end (20-22) to the spine (16). Other aspects of the invention concern a roll stand and rolling mill for forming the bar or post (15).

Claims

1. A method of rolling a bar consisting of steel or alloy steel, wherein said method comprises the step of passing the bar consisting of steel or alloy steel through at least one roll stand configured to roll a bar consisting of steel or alloy steel to thereby form a rolled bar, wherein the rolled bar has a central longitudinal axis and three interconnected arms, each of which extends along the central longitudinal axis and generally radially from the central longitudinal axis adjacent one another, and wherein each of said three interconnected arms are from 2.0 mm to 4.0 mm thick, wherein the roll stand comprises: only three roll assemblies for shaping said arms, with each said roll assembly comprising: a roll having an axis of rotation and a circumferentially extending contoured rim extending between any two adjacent bar arms, a roll positioner for moving the roll towards or away from the pass line, and a drive shaft extending from the roll; wherein the roll assemblies define a pass line along which the central longitudinal axis of the bar substantially travels; and wherein the rolls are spaced about the pass line with their said axes of rotation in a common plane and said contoured rims provide a void through which the pass line extends and shape the arms of the bar as the bar passes through the void, and wherein the roll positioners are capable of moving the rolls incrementally within the common plane and along an axis perpendicular to the axis of rotation of each said roll so as to change the size of the void; and wherein the rolls abut each other to thereby encapsulate the bar as it passes through the void; and wherein the method comprises the step of varying the rotational speed of at least one roll within any one roll stand independently of the rotational speed of another roll within the any one roll stand; and wherein the at least one roll stand is a plurality of roll stands arranged in sequence, wherein the rolls of each of said roll stands have circumferentially extending contoured rims adapted to incrementally form the three interconnected arms of the rolled bar.

2. The method of claim 1, wherein at least one of said contoured rims is shaped to form a said arm generally tapered in the direction from a free end of the arm to the central longitudinal axis of the bar.

3. The method of claim 1, wherein each said contoured rim is shaped to form a said arm generally tapered in the direction from a free end of the arm to the central longitudinal axis of the bar.

4. A rolled steel bar formed by the method according to claim 1.

5. The method of claim 1, wherein at least one said roll assembly further comprises a bearing located each side of the roll through which the drive shaft extends.

6. The method of claim 5, wherein the roll stand further comprises a housing for containing the rolls, and wherein the roll positioner is a clamp assembly extending from said bearing located either side of the roll and connected to the housing by way of position adjusting screws.

7. The method of claim 1, wherein the roll stand further comprises a housing for containing the rolls, wherein the housing comprises a front wall having an inlet for the bar and a rear wall having an outlet for the bar, so that the pass line extends centrally through the inlet and outlet.

8. The method of claim 7, wherein the inlet and outlet are shaped to allow the rolls to extend partway there through.

9. The method of claim 1, wherein each said contoured rim has circumferentially extending outer flanges bordering a circumferentially extending inner recessed region having an apex, and wherein the rim has a circumferentially recessed groove located in the inner recessed region adjacent each outer flange, to thereby shape a bar having arms each having a bulbous or enlarged region at a free end thereof.

10. The method of claim 1, wherein the rolled bar has a property selected from the group consisting of: (i) being made of steel alloy, stainless steel, coated steel, anodised steel, galvanised steel or ungalvanised steel; and (ii) a length of approximately 1 m to 3 m.

11. The method of claim 1, wherein the rolled bar has a radial length of each of said arms of approximately 10 mm to 40 mm.

12. The method of claim 1, wherein the rolled bar when viewed on end is generally Y-shaped, and the angle between two upstretched shorter arms of the Y is between about 80 and 130 degrees.

13. The method of claim 1, wherein the rolled bar is a fence post.

14. The method of claim 1, wherein each said roll assembly further comprises a bearing located each side of the roll through which the drive shaft extends.

15. The method of claim 1, wherein one arm of the three interconnected arms of the rolled bar is radially longer than other arms of the three interconnected arms of the rolled bar.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows the profile of a known Y-profile steel post (bar);

(2) FIG. 2 shows part of a 2-high mill stand for rolling the post of FIG. 1;

(3) FIG. 3 is an end view (profile/cross section) of a post (bar), according to an embodiment of the present invention;

(4) FIG. 4 is a perspective view of the post shown in FIG. 3;

(5) FIG. 5 is a side elevation view of the post of FIG. 4;

(6) FIG. 6 is a perspective view of a roll stand for forming the post of FIG. 3, according to an embodiment of the present invention;

(7) FIG. 7 is a perspective view of part of the roll stand of FIG. 6;

(8) FIG. 8 is an elevation view of part of the roll stand of FIG. 6;

(9) FIG. 9 is a cross sectional view of three rolls of three roll assemblies of the roll stand of FIG. 6 and the post of FIG. 3 (shown in phantom), according to an embodiment of the present invention;

(10) FIG. 10 is a general cross sectional view of part of a roll of a roll assembly, according to an embodiment of the present invention;

(11) FIG. 11 is a partly exploded cross sectional view of three rolls of three roll assemblies of the roll stand of FIG. 6, according to an embodiment of the present invention;

(12) FIG. 12 is a partly exploded cross sectional view of three rolls of three roll assemblies, according to an embodiment of the present invention;

(13) FIG. 13 is a radial cross sectional view of four rolls of a roll stand and a four-armed bulbous post, according to another embodiment of the present invention; and

(14) FIG. 14 is a schematic showing processing steps of a metallic bar in a roll mill to form the post as shown in FIGS. 3-5.

BEST MODES FOR CARRYING OUT THE INVENTION

(15) In the figures, like reference numerals refer to like features.

(16) Referring first to FIG. 1, there is shown a known furcated Y-profile steel post 1 (bar 1). The post 1 has a spine 10, a central longitudinal axis extending along the spine 10 and three lateral arms (flanges) 2, 3, 4 that extend along a length of the spine 10 and generally radially from the spine 10. Arms 3 and 4 extend from the spine 10 at approximately 100-120 degrees relative to one another. Arm 2 is longer than arms 3 and 4 and a free end 5 of the arm 2 is tapered.

(17) FIG. 2 shows part of a two-high mill stand for rolling the post 1 of FIG. 1 and has an upper roll 7 and a lower roll 8.

(18) Referring now to FIGS. 3-5, there is shown a furcated Y-profile steel post 15 (bar 15) according to an embodiment of the present invention. The post 15 has a spine 16, a central longitudinal axis extending along the spine 16 and three arms 17, 18, 19 that extend along a length of the spine 16 and generally radially from the spine 16. Arms 18 and 19 extend from the spine 16 at approximately 100-120 degrees relative to one another. Arm 17 (long arm 17) is longer than arms 18 and 19. A free end 20-22 of each arm 17-19 is enlarged/bulbous 20-22 relative to an intermediate region of the arm 17-19 extending between the free end 20-22 and spine 16. Such a post 15 profile and like profiles cannot be produced by the conventional 2-high mill stand shown in FIG. 2.

(19) As seen in FIGS. 4 and 5, the long arm 17 has openings 24 spaced along a length of the arm 17 for retaining fencing wires and other types of fencing members. The post 15 also has a pointed ground anchoring end 25, as seen in FIG. 5.

(20) Referring now to FIGS. 6-9, there is shown a roll stand 30 for a rolling mill, for forming the post 15 shown in FIGS. 3-5. The roll stand 30 includes a housing 31 (see FIG. 6), a pass line 11 (see FIG. 9), a void 12 and three roll assemblies 32-34.

(21) Each roll assembly 32-34 includes a roll 37-39 having an axis of rotation and a circumferentially extending contoured rim 40-42 for forming/shaping said arms 17-19. The post arms 17-19 are shown in phantom/outline. The rolls 37-39 are spaced about the pass line 11 with their axes of rotation in a common plane and with their contoured rims 40-42 providing the void 12 through which the pass line 11 extends. The rolls 37-39 extend generally radially relative to the pass line 11 at about 120 degrees relative to one another. The contoured rim 40-42 of each roll 37-39 forms/shapes radial halves of two adjacent arms 17-19.

(22) The number of rolls of the roll stand will depend on the number of arms of the bar/post. For example, a three-armed post like post 15 would require three rolls, a four-armed bar like post 100 of FIG. 13 (shown with cross hatching) would require four rolls 101-104, and a five-armed post would require five rolls, and so forth.

(23) Referring now to the general depiction of a rim 111 (40-42) in FIG. 10, the shape/profile of each contoured rim 111 (40-42) will depend on the shape and thickness that the post arm is to have. Each contoured rim 111 (40-42) has circumferentially extending outer flanges 112, 113 (raised/proud edges) bordering a circumferentially extending inner recessed region 114 (shown with cross hatching) having an apex 115. That is, the inner recessed region 114 having the apex 115 is substantially V-shaped/wedge-shaped when viewed in radial cross section.

(24) The outer flange 112, 113 (raised edge) height determines the thickness of the free end of one radial half of an arm. The flange 112, 113 height together with the inner recessed region 114 having the apex 115 determines the shape and thickness of radial halves of two adjacent arms. The greater the distance between adjacent inner recessed regions 114, the greater the void and the thicker the arms. The greater the distance between the rim apexes 115 and the pass line, the thicker the spine where the arms intersect one another.

(25) As seen in FIG. 11, for the post of FIG. 3, the contoured rim 40-42 of each roller 37-39 has a circumferentially extending groove 120 located in the inner recessed region (not labelled) adjacent each outer flange 112, 113. A circumferentially extending groove 118 located in the apex 115 of the inner recessed region 40-42 can produce a bulbous/enlarged region 118 where two adjacent arms intersect at the central longitudinal axis (spine).

(26) As seen in FIG. 12, for a post whereby the free end of each arm is less bulbous/enlarged yet tapered in the direction of the free end to the central longitudinal axis (spine), each circumferentially extending groove 125 located adjacent each outer flange 112b, 113b (of each contoured rim 40b-42b) can be of greater width and of decreasing depth in the direction from the outer flange 112b, 113b to the apex 115b.

(27) As seen in FIG. 6, the housing 31 has a front plate wall 45 having a Y-shaped inlet 47 for the post and a rear plate wall 46 having a Y-shaped outlet (not shown) for the post 15. The pass line 11 extends through a centre of the inlet 47 and outlet. The inlet 47 and outlet are shaped so as to allow the rolls 37-39 to extend partway there through, as shown in FIG. 6.

(28) Each roll assembly 32-34 includes a drive shaft 51-53 extending from the roll 37-39 and a pair of bearing blocks 57-62 through which the shaft 51-53 extends. Ends of the shafts 51-53 are keyed to a respective drive in a conventional way, such that the rotational speeds of the rolls 37-39 can be varied as required (e.g. when rolls of differing diameter are used).

(29) Each roll assembly 32-34 includes a clamp assembly 70-72 extending from the bearing blocks 57-62. The clamp assemblies 70-72 hold the rolls 37-39 in the correct position within the housing 31 relative to the pass line 11. Each clamp assembly 70-72 is connected to the housing plate walls 45, 46 by way of a body 82-84 and screws 80a, 80b, 80c, 80d, 80e that extend through the body 82-84 (only some of which have been labeled) as seen in FIGS. 6 and 8.

(30) Each clamp assembly 70-72 includes a pair of position adjusting screws 90-95 for adjusting the position of the rolls 37-39 relative to the pass line 11. A shaft of each screw 90-95 is externally threaded and extends through the body 82-84. A head of each screw 90-95 is located one side of the body 82-84 and the other end of each screw 90-95 is fastened to a bearing block 57-62, as seen in FIG. 8. Turning the screws 90-95 in a first direction moves the rolls 37-39 incrementally towards the pass line 11 and turning the screws 90-95 in a second opposite direction moves the roll 37-39 incrementally away from the pass line 11. In this way, the positioning of the rolls 37-39 can be individually readjusted when requirede.g. when a roll is worn.

(31) The rolling mill may utilise cold profile rolling or hot profile rolling. The rolling mill will typically be a normal mill set up but comprising a plurality of roll stands like stand 30 arranged in sequence, each of which have rolls having specifically contoured rims for forming the arms of the post 15 in a step-by-step manner. Normally the contours would be designed with the aid of a computer.

(32) As generally depicted in FIG. 14, in order to manufacture a post/bar like post 15 (or even post 1), a steel pre-rolled bar/post is fed sequentially through roll stands like stand 30 of the mill, until a post 15 of the desired profile is achieved. Since arm 17 is longer than the other two arms 18, 19which means that the profile is not triangularly symmetricalthe rolling speed of each roll 37-39 will need to be adjusted accordingly.

(33) The post 15 may be cut to the required length using a die/flying shear system to form the post 15 or a longer intermediate post.

(34) The post 15 may be further processed by way of being cut to produce the ground anchoring point 25. The post 15 may be hole- or slot-punched using a punch of the roll mill. The post 15 may be subjected to anti-corrosion techniques (eg. coated, plated, anodised etc) using a baking or galvanisation line. These steps are generally depicted in FIG. 14.

(35) Some of the advantages of the present invention include the following: The long arm of the bar/post is less likely to get stuck in the rolls of the roll stand. Hence, the radial length of the long arm need not be shortened, nor heavily tapering. The post section can have extremely good dimensional tolerance and finish. Premature roll (die) wear is less likely, and worn rolls can be utilised by altering their position and rotational speed. A greater degree of profile shape design is possible due to the roll geometry and configuration. The 3-roll design of the roll stand enables the Y-shaped profile to be formed with fewer roll stands arranged in sequence. The profiles having enlarged/bulbous free ends increase the strength of the post as well as the strength to weight ratiothereby reducing the cost of the post and increasing strength, without reducing the surface area holding strength in the soil.

(36) The foregoing embodiments are illustrative only of the principles of the invention, and various modifications and changes will readily occur to those skilled in the art. The invention is capable of being practiced and carried out in various ways and in other embodiments. It is also to be understood that the terminology employed herein is for the purpose of description and should not be regarded as limiting.

(37) The term comprise and variants of the term such as comprises or comprising are used herein to denote the inclusion of a stated integer or stated integers but not to exclude any other integer or any other integers, unless in the context or usage an exclusive interpretation of the term is required.