Rolling Articles

Abstract

This invention relates to a method of forming headed articles such as bolts from round bar. The bar is rotated in the throat between two rollers and has a part extending beyond the roller surface. A stylus is pressed against the face of the projecting end to form an indentation in this face of the rolling bar and as the indentation increases in size a head is formed on the bar. The head can be subjected to further working if necessary.

Description

This invention relates to the formation by rolling of headed components, such as bolts, mushroom valves and so on, from cylindrical workpieces that have been cropped from round bar.

According to one aspect of the invention there is provided a method of rolling articles comprising rolling a blank within a throat defined by two or more rolling surfaces with one end projecting beyond the throat, arresting axial movement of the blank in the direction of the other end, and forming a head on the projecting end by engaging the end with an inclined rotating end forming stylus that is rotated in unison with the blank and is forced in line contact against the projecting end to spread it.

According to another aspect of this invention there is provided, apparatus for rolling articles comprising at least a pair of rolling surfaces which define between them a throat; stop means at one end of the throat for restraining movement of a workpiece received in the throat in one axial direction; and inclined rotatable, stylus located at the other end of the throat and having a shaped preferably conical end for engaging in line contact the end face of a workpiece located in the throat; and means for urging the stylus towards the throat, preferably in a direction parallel to the axis of the throat.

Embodiments of the invention will now be described by way of example with reference to the accompanying detail diagrammatic drawings which are sections showing workpieces being acted upon during rolling.

In the drawings:

FIG. 1 shows the parts at the commencement of forming the head on a rolled article,

FIG. 2 shows the parts after the head has to a large extent been formed,

FIG. 3 shows the parts after completion of the head forming operation,

FIG. 4 shows parts for forming a hollow head,

FIG. 5 shows an end forming operation using a shaped stop, and

FIG. 6 shows nails being headed and pointed simultaneously.

Referring now to FIG. 1 there is shown a cylindrical workpiece 11 contained in the throat between two rotatable rolls 12. The rolls 12 each have a stepped down portion 14 to provide an enlarged throat part 15. The workpiece 11 is held within the throat against axial movement in one direction by stop means comprising a rotating stop 16. The workpiece 11 is located so that its end part 17 projects into the enlarged throat part 15. It should be noted that the diameter of the enlarged throat part 15 is so much greater than the diameter of the workpiece that the end part 17 is in effect freely located.

An inclined stylus 18 having a conical end 19 is rotatable in a bearing 21 and is located so that its point lies on the axis 22 of the workpiece 11. The stylus 18 may be freely rotatable or it may be driven so that it rotates at the same speed as the workpiece. Means, not shown are provided to move the bearing housing 21 towards the rolls 12 so that the stylus is forced into the end of the workpiece. Such means may comprise an hydraulic jack, a screw jack arrangement or the like which is arranged to provide a thrust parallel to the workpiece axis 22.

As the stylus is forced towards the end face 24 of the workpiece it pierces it and runs in line contact therewith gouging a recess 25 out of the end face 24. As the recess 25 is formed, the projecting end 17 of the workpiece 11 expands as shown in FIG. 2. Continued movement of the stylus 18 causes the sides of the expanded end of the workpiece 11 to contact the stepped down portions 14 of the rolls 12. A cylindrical roll 26 which is rotatable about an axis (not shown) at right angles to workpiece axis 22, i.e., having its working surface normal to the axis 22, now engages the end face of the workpiece on one side of the workpiece axis and rolls the latter into the enlarged throat portion 15. A headed article 27 is produced (see FIG. 3).

The roll 26 is preferably mounted for rotation about a fixed axis and each blank passes through a throat defined between it and an end face of the rolls 12 or of a C-frame. Alternatively, where the blank is mounted about a fixed axis or one that is nearly so, the roll 26 may be retractable, to be brought into operation after withdrawal of the stylus.

It should be noted that the pressures required to form the head are considerably less than those required for forging heads. Consequently the rolls 12 last much longer than the dies and also the radius of curvature at the join of the head to the shank will be smaller than with forged heads.

In a modification shown in FIG. 4, the bearing housing 31 is tiltable and the enlarged side portion of the stylus 32 has an annular end face 34. The stylus which is inclined has a conical end which is located against the center of the end face of the workpiece. The stylus 32 is forced into this end face so that its surface applies pressure in line contact with the end face and gouges out a recess as described above.

When a sufficiently large recess has been gouged out, the bearing housing 31 is pivoted round so that the stylus axis is brought closer to and then into coincidence with the workpiece axis. Thereafter the stylus is forced into the workpiece end so that the annular end face 34 of the stylus 32 butts against the end face of the workpiece to square it off. The stylus 32 is then removed to leave a recessed head on the workpiece. This workpiece can then be used for Allen screws of the like.

In this embodiment, the stop means to prevent the workpiece being forced out of the throat by the stylus is constituted by a flange 35 of one of the rolls 36 and 37.

It will be appreciated that the stop means may be any suitable configuration and may itself carry out profiling function. For example it may comprise a stop which is embossed to form a concavity in the workpiece as at 40 in FIG. 5. In this embodiment the stylus 41 has a domed head 42 surrounded by an annular recess 43 which in turn is located within an annular rim 44. The front face 45 of this rim 44 is frusto-conical, the cone angle being very large. The axis 46 of the stylus 41 is inclined to the axis 47 of the workpiece 48 by a very small angle .alpha. (which is shown exaggerated in FIG. 5 so that there should be line contact between the domed head 42 and the end face of the workpiece 48).

As in the first described embodiment the stylus 41 is moved inwardly parallel to the workpiece axis 47 and is rotated either by friction with the workpiece or by a separate drive means. The projecting end of the workpiece 48 which was initially of a shape shown in broken lines is shaped by the stylus and a centrally recessed head 51 is formed in the annular recess 43.

Also the stop means may be constituted by another stylus so that both ends of the workpiece can be headed. It will also be appreciated that additional profiling of the workpiece may take place during rolling. For example where both ends of the workpiece are headed, the workpiece may be pointed and conveniently parted so that two headed articles would be formed. This technique could with advantage be carried out for forming nails as shown in FIG. 6 where two styli 61 are provided. The styli have conical end faces 62 of large cone angle and are arranged with their axes 63 slightly inclined at an angle .beta. which may be of the order of 1.degree. to the axis 64 of the workpiece 65. The rolls 66 and 67 each have a central raised rib 68 which points the nails and parts them from one another. As in all the embodiments the apex of the end face of each stylus contacts the end face of the workpiece initially at its center point.

The nature of the assembly of rollers defining the throat will vary, depending upon whether the rolls merely constitute a holder to secure the blank while it is being headed, without any, or any significant, reduction of the blank diameter; or whether the blank is to be profiled or reduced in diameter simultaneously with the heading operation. In one form and as shown in the drawings the rolls may be a solid pair but one may be hollow and the other eccentrically mounted within its cavity. In this form of the invention, the blank is nipped in the convergent throat and is entrained through the throat with reduction in diameter. It follows that the stylus must move in unison with the blank and advance in a path which is parallel to the path followed by the blank, but not within the throat. Similarly, if the stop is other than the flange of one of the rolls, the stop surface must also move along a path parallel to the path of the blank through the throat. When a procession of blanks passes through the throat, the stylus (and the stop, if necessary) may be rotatably mounted in cages that are geared to revolve at a speed which is that at which the blanks are drawn into and through the throat. The styli and stops need not themselves be driven, but may derive their rotation by frictional engagement with the blanks.

Then, the rolls may be a series of three of more, although usually three, defining the throat between them. If the rolls be rotatable about fixed axes, so that the throat is merely a device to hold the blank, there is no complication in mounting of the stop and stylus. They are mounted about fixed axes (which, if the stylus is to be tilted, can be moved to provide the tilting movement). On the other hand, if the throat is to be narrowed to profile the blank or to reduce it in diameter, the rolls must move inwardly symmetrically, if the stylus and stop are rotatable about fixed axes. If the inward movement of the rolls causes the axis of the throat to wander, then means are provided to ensure that the stylus and stop axes move correspondingly.

Finally, there is the arrangement which can be akin to a combination of the two-and-three-roll systems. One roll is replaced by a stationary frame that is C-shaped. The other is mounted within it, though not necessarily eccentrically. The arcuate throat defined between the frame and the roll converges and a series of blanks can be fed through it in a procession, each associated with a stop surface and a stylus geared together to advance with the blank. The blank is reduced or profiled as it passes through the throat. The same arrangement would be applicable where there is no convergence, when the frame and roll would be merely a means to hold the blanks as they are operated on by the styli. On the other, the throat may be lined along one wall with a series of small rolls which are mounted in a holder, such as a cage, to advance through the throat, with blanks held in the space defined between each trio of rolls. Each roll forms part of two trios, so that, when the machine is fully charged, each roll is in simultaneous engagement with two blanks. Each trio is a three-roll system, differing only from the three-roll system discussed above in that it moves in a prescribed orbit through the throat, and rotation is imparted to the rolls by frictional engagement with the walls of the throat.

The deformation imposed by the stylus on the blank may suffice, as is the case in FIGS. 4 and 5 but usually further deformation is called for, and a subsequent rolling operation, such as shown in FIG. 3 may be carried out.

While it is not impossible to carry out the technique of the invention on cold blanks, it is preferred to heat the blanks to facilitate their deformation. For instance, localized heating to the zone to be deformed to make the head may be applied by electrical induction before application of the former.

The technique of the invention enables a large throughput to be achieved of components which are precisely made and well finished without excessive wear of the apparatus.

It will be understood that flanges and the like for example on automobile half-shafts may be formed by the method and operation of this invention and the term `head` as herein used is intended to include in its meaning a flange or the like unless the contrary is obvious from the context.

Claims

I claim:

1. A method of rolling articles comprising rolling a blank within a throat defined by two or more rolling surfaces, with one end projecting beyond the throat, arresting axial movement of the blank in the direction of the other end, and forming a head on the projecting end by engaging the end with an inclined rotating stylus that is rotated in unison with the blank and is forced in line contact against the projecting end to spread it.

2. A method as claimed in claim 1 comprising further working the head after it has been formed by the stylus.

3. A method as claimed in claim 2 in which the further working of the head is affected by a roller to the working surface of which the workpiece axis is normal.

4. A method as claimed in claim 1 further comprising restricting the outward growth of the head.

5. A method as claimed in claim 1 further comprising forming a recess in the head.

6. Apparatus for rolling articles comprising at least a pair of rolling surfaces which define between them a throat; stop means at one end of the throat for restraining movement of a workpiece received in the throat in one axial direction; an inclined rotatable stylus located at the other end of the throat and having a shaped end for engaging in line contact the end face of a workpiece located in the throat; and means for urging the stylus towards the throat.

7. Apparatus as claimed in claim 6 wherein the end face of the stylus is conical.

8. Apparatus as claimed in claim 6 wherein the end face includes a projection surrounded by a recess into which material of the article will be forced when the projection enters the end face of a workpiece.

9. Apparatus as claimed in claim 6, wherein the stylus is movable towards the throat in a direction parallel to the axis of the throat.

10. Apparatus as claimed in claim 6, wherein the rolling surfaces have at least one end of the defining throat portions of different dimensions so as to define a throat portion of enlarged diameter.

11. Apparatus as claimed in claim 6, wherein the means defining one of the roller surfaces has a flange which constitutes the said stop means.