GB2134427A - Apparatus for the hydroplastic reduction of tubular apparatus for rolling blanks - Google Patents

Abstract

Apparatus for rolling tubular blanks utilises fluid between the internal surface of a blank 17 and a mandrel 13. The apparatus in our form comprises a hydraulic cylinder 3 within a hollow spindle and rotatable therewith, the cylinder containing a piston 4 and one end of the mandrel. Duct means 14, 15 supply hydraulic pressure to the outside of the mandrel on which the blank is located. Locking means 18, 19 hold the blank on the mandrel against rotation and roller means 22 having associated heater means 21 act on the surface of the blank to effect the hydroplastic reduction thereof while fluid is located in a deformation space 16 between the blank and the mandrel. The rollers 22 are controlled by a template (38). In a modification, pressure pulses are produced by plungers (51) urged into the rotating cylinder by stationary cams (52). <IMAGE>

Description

SPECIFICATION Apparatus for the hydroplastic reduction of tubular blanks This invention relates to an apparatus for the hydroplastic reduction of tubular blanks which is to be used in the metal working industry.

In USSR Authors Certificates Nos. 524,578 and 603,472 there are disclosed apparatuses for tube reduction comprising coiler rolls which undergo rotation around their longitudinal axes and forward motion along the length of the tubular blank as the latter, being reduced in thickness, slides over a mandrel.

A disadvantage of such an apparatus is its rather limited capability because the running of the blank overthe mandrel as the blank undergoes reduction is a cold process and hence it is impossible to achieve very high deformation rates and to process tube external surfaces with very pronounced relief.

Another disadvantage of such apparatus is the unfavourable working conditions encountered, involving high contact loads and dry friction between the mandrel surface and the internal surface of the blank being processed; this has a negative effect on the quality of the surfaces.

According to the present invention, there is provided an apparatus for the hydropiastic deformation of a tubular blank, which comprises a hollow rotatable spindle, a hydraulic cylinder within the spindle for rotation therewith and, for contacting by fluid within a cavity in the hydraulic cylinder, a piston and one end of a mandrel likewise for rotation therewith, the hydraulic cylinder being formed as a multi-step cylinder with the piston and defining therewith a plurality of sequential zones subjectable to different fluid pressures therein, duct means being provided in the apparatus for supplying fluid under pressure to said zones from a source external of the apparatus for irreversible fluid flow to one said zone and thence through duct means communicating it with the surface of an additional part of the mandrel on which the blank is to be located in response to fluid pressure increase impulses achievable in the said one zone, the apparatus additionally including means for locking the blank against rotation independently of the mandrel and, provided externally of the mandrel, roller means and associated heater means displaceable therewith for acting on the blank to effect reduction thereof.

A cap will generally be postioned on the end of the mandrel remote from the hydraulic cylinder to abut the blank and close off the fluid-containing deformation space present in use between blank and mandrel.

The apparatus of this information enables hydroplastic reduction of tubular blanks to be carried out in a way which will enable high deformation rates to be achieved, will permit the axial component of the deformation force to be increased and allow a generally more favourable working regime to be created as a result of fluid friction existing between the internal surface of the blank and the working surface of the mandrel. These features are enhanced particularly because the apparatus of this invention enables deformation to be carried out at elevated temperatures. The extent of the axial component of the deformation force which can be achieved is related to the size of impulse superpressure which is achievable. The fluid friction which is achieved will lead to an improvement in the quality of the internal surface of the worked blank and to a prolonging of the life of the mandrel.

With one form of apparatus embodying this invention, three aforesaid zones are provided by an initial chamber on the side of the piston remote from the mandrel, an end chamber of larger cross-section intermediate the opposite end of the piston and one end of the mandrel and communicable with the initial chamber through duct means through the piston having a check valve therein for preventing fluid flow therethough towards the initial chamber, and an intermediate chamber of largest crosssection having a middle portion of the piston passing therethrough and providing a surface on which fluid can act to drive the piston towards said end of the mandrel, there being duct means associated with the intermediate chamber for supply of fluid under pressure thereinto for acting on said surface of the piston.

With such a form of apparatus, the combination of diameters of the chambers and the supply of fluid thereinto enables fluid under pressure impulses to be supplied to a deformation space between the mandrel and a blank thereof, through duct means through the mandrel, when the apparatus is in use, as will be apparent from the description of this embodiment as illustrated in the drawings which follows.

In an alternative form of apparatus embodying the invention, the aforesaid zones lie sequentially within a single cavity within the hydraulic cylinder, which zones are defined by one or more impulse pistons passing into the cavity through the wall of the hydraulic cylinder at a plane or at each of a plurality of planes at intervals therealong.

More particularly one or more impulse pistons is/are mounted radially within the hydraulic cylinder at each zone-defining plane with the outer end of each impulse piston being contactable by cam means located in the wall interior of housing means of the apparatus, with the inner ends of the pistons entering the hydraulic cylinder for contact by fluid therein. Preferably, the number of impulse piston planes is such that the cavity is divided into three or more zones.

The front end of the mandrel, which is itself preferably formed of magnetically soft material, is formed as a chute in which is fitted a throttle ring. In order that profiling of the blank can be achieved simultaneously with its reduction, the roller means may be additionally associated with a copying device including a template for deforming the blank in accordance with the profile of the template as the blank undergoes reduction.

For a better understanding of the invention and to show how the same can be carried into effect, reference will now be made by way of example only to the accompanying drawings wherein: Figure 1 is a longitudinal section through one form of apparatus embodying this invention; Figure 2 shows in longitudinal section a rearwardly extending part of the apparatus of Figure 1; Figure 3 is a cross-section through the apparatus of Figure 1 (and aiso that of Figure 4) at A-A; Figure 4 is a longitudinal section through a second form of apparatus embodying this invention; and Figure 5 is a cross-section through the apparatus of Figure4at B-B.

The apparatus for hydroplastic deformation of tubular blanks shown in Figure 1 comprises a cylindrical housing 1 with a cylindrical spindle 2 therein. Within the spindle 2, there is located a hydraulic cylinder 3 housing a piston 4therein. A spigot 5 mounted to the housing 1 is in engagement with another spigot 6 in which a hole is drilled for fluid feed therethrough. Hydraulic cylinder 3 is a three-step cylinder and correspondingly piston 4 is a three-step piston, there being formed therebetween three sequential chambers, namely an initial chamber 7, an intermediate chamber 8 and an end chamber 9. The initial chamber 7 is formed between the front end of piston 4 and the second spigot 6 and has the smallest diameter and the intermediate chamber 8 is of largest diameter.In piston 4, there is provided a duct 10 connecting the initial chamber 7 with end chamber 9, and in which there is fitted a check valve 11 opening in the direction of fluid travel, that is from front to rear of piston 4. In spigot 5there is provided a by-pass channel 12 for fluid feed to the intermediate chamber 8.

A mandrel 13 connected to spindle 2 is fitted to the rear end of hydraulic cylinder 3. Mandrel 13 includes an axial duct 14 and radial ducts therefrom for feeding hydraulic fluid into a deformation space formed between mandrel 13 and tubular blank 17 fitted thereon for sliding movement of deformed metal thereover. The blank is locked against turning by a keyed bush 18 and sleeve 19 pressed to mandrel 13 with interposition of a sealing gasket 20. An induction heater 21 and roller head 22 fit over blank 17 for sliding engagement therewith.

Hydraulic fluid is supplied to initial chamber 7 and intermediate chamber 8 by means of a hydraulic system consisting of a gate distributor 23 connected at one side through piping 24 with a pressure gauge 25 and electromagnetic valve 26, and through its other side through piping 27 with another pressure gauge 28 to the duct through the second spigot 6. As can be seen from Figure 2, a sleeve 30 is pressed to the rear end of mandrel 13 over the front end of deformed part 29 of the blank. At this end of the mandrel 13 is provided a chute 31 in which is fitted a throttle ring 32.

In order to enable the apparatus to be used in the hydroplastic deformation of tubular blanks, there is provided a copying system as shown in Figure 2.

This system is mounted on through axis 34 which is mounted within sleeve 30 and comprises a carrier 35 and, attached to axis 34 by means of a nut 36 and a lock net 37, a copying template with a pawl 39 which is connected to the roller head in a conventional manner not shown in the drawings. The copying template and pawl 39 are carried on a further carrier 40, while a second hydraulic cylinder 41 with an additional piston 42 is mounted to carrier 35.

The apparatus shown in Figure 4, in which like reference numerals denote like parts in Figure 1, consists of a hydraulic cylinder 3 fitted to a hollow rotating spindle 2 at one end and with its other end occupied by a manifold 43 with a duct 44 therethrough which includes a check valve 11. A sealing element 46 is positioned between the manifold 43 and the inner surface of hydraulic cylinder 3 whose central chamber is closed thereby. The manifold 43 is locked against axial movement by an inner flange 48 and a stop piece 49 and against turning by an outer flange 50. Radiai bores in hydraulic cylinder 3 house, with an adjustable gap, impulse pistons 51 contactable by cams 52 fitted within the inner wall surface of housing 1 oftheapparatus.Amandrel 13 with an axial bore 14 and radial bores 15 is attached to hydraulic cylinder 3.The bores 14 and 15 connect the central chamber of hydraulic cylinder 3 with the deformation space 16. A sealing element 53 is fitted between the mandrel 13 and cylinder 3. A blank 17 is placed on mandrel 13 with one end engaged by keyed bush 18fixedto mandrel 13. Several roller heads in an offset arrangement as shown in Figure 3 act on the blank 17 to effect deformation of its external surface.

The apparatus shown in Figures 1 and 2 is operated inthe following manner: A blank 17 is passed over mandrel 13 and sleeve 30 is pressed over the free end of the mandrel to close off the space existing between mandrel and blank and to cause the blank to engage keyed bush 18 and sleeve 19. Fluid under high pressure P1 is fed through the gate distributor 23 to the initial chamber 7 and from there to end chamber 9 where, because of differences in the diameter of piston 4 along its length, the fluid causes the piston to be displaced to the left. At the same time the mandrel 13 is undergoing rotation.Afterwards, fluid flow under low pressure P2 is fed into intermediate chamber 8 and initial chamber 7 as a consequence of which piston 4 is displaced to the right and the high pressure P3 which had been set up in the end chamber is reduced as fluid under high pressure is displaced along axial duct 14 and radial ducts 15 and is fed to deformation space 16 of mandrel 13. Roller head 22 is actuated to advance along the outer surface of blank 17 to reduce its thickness under conditions of semi-hot rotational extrusion which then exist with induction heater 21 being in an operating condition.

The actual profile deformation makes use of the aforementioned copying system. When the end of part 29 of blank 17 at which reduction has occurred is moved to the right, sleeve 30 moves towards the carrier35 and second carrier 40 and in turn the copying template 38. The pawl 39 remains fixed and during the movement of the copying system to the right it follows the contours of the copying template 38 and transmits through constructional elements which are conventional and not shown in Figure 2 changes in these contours so that they are reproduced to a set scale in the radial displacement of the work elements of the roller head 22. Hence the profile of the copying template 38 is reproduced on the exterior of tubular blank 17 as it is reduced in thickness under the action of the roller head.

The apparatus shown in Figure 4, in contrast, operates as follows: Tubular blank 17 is positioned on mandrel 13.

Roller head 22 is moved towards the blank 17 until the first row of rolls touches it. Spindle 2 is then rotated and the roller head 22 advances. At the same time, fluid under a specified pressure P1 is fed through hole 44 of manifold 43 in hydraulic cylinder 3 and this fluid passes through duct 14 and radial duct 15 of mandrel 13 to enter the deformation space 16. As a result of the rotation of hydraulic cylinder 3, the impulse pistons 51 make contact with cams 52 at the outer end thereof and reciprocal motions result.

Hence high impulse pressures P pulse are created in hydraulic cylinder 3. These high impulse pressures are transmitted through the ducts in mandrel 13 into the deformation space 16 to enable the hydropiastic processing of the internal surface of blank 17 to take place. The connecting flanges of spindle 2, hydraulic cylinder 3 and mandrel 13 are so sized that they perform the functions of a fly wheel.

The impulses imparted to the fluid enclosed in the chamber of the hydraulic cylinder are generated by using a large number of impulse pistons 51 fitted radially in different sections (B. C....K in Figure 4) along the length of hydraulic cylinder 3, with an optimum number desirably being positioned in each section. Each of the impulse pistons 51 is actuated many times in one revolution depending on the number of cams in the section. The magnitudes of the impulse pressures are determined by variations in the speed of revolution of the spindle 2, the diameters of the impulse pistons 51 and their stroke, and the overall pressures built up depend on the number of impulse pistons 51 and cams 52 in the sections B, C K of Figure 4).

Claims (12)

1. An apparatus for the hydroplastic deformation of a tubular blank, which comprises a hollow rotatable spindle, a hydraulic cylinder within the spindle for rotation therewith and, for contacting by fluid within a cavity in the hydraulic cylinder, a piston and one end of a mandrel likewise for rotation therewith, the hydraulic cylinder being formed as a multi-step cylinder with the piston and defining therewith a plurality of sequential zones subjectable to different fluid pressures therein, duct means being provided In the apparatus for supplying fluid under pressure to said zones from a source external of the apparatus for irreversible fluid flow to one said zone and thence through duct means communicating it with the surface of an additional part of the mandrel on which the blank is to be located in response to fluid pressure increase impulses achievable in the said one zone, the apparatus additionally including means for locking the blank against rotation independently of the mandrel and, provided externally of the mandrel, roller means and associated heater means displaceable therewith for acting on the blan to effect reduction thereof.

2. Apparatus as claimed in claim 1, additionally comprising a cap for positioning on the end of the mandrel remote from the hydraulic cylinder to abut the blank.

3. Apparatus as claimed in claim 1 or 2, wherein three said zones are provided by an initial chamber on the side of the piston remote from the mandrel, an end chamber of larger cross-section intermediate the opposite end of the piston and one end of the mandrel and communicable with the initial chamber through duct means through the piston having a check valve therein for preventing fluid flow therethrough towards the initial chamber, and an intermediate chamber of largest cross-section having a middle portion of the piston passing therethrough and providing a surface on which fluid can act to drive the piston towards said end of the mandrel, there being duct means associated with the intermediate chamber for supply of fluid under pressure thereinto for acting on said surface of the piston.

4. An apparatus as claimed in claim 1 or 2, wherein the said zones lie sequentially within a single cavity within the hydraulic cylinder, which zones are defined by impulse pistons passing into the cavity through the wall of the hydraulic cylinder at a plane or at each of a plurality of planes at intervals therealong.

5. An apparatus as claimed in claim 4, wherein one or more impulse pistons is/are mounted radially within the hydraulic cylinder at each zone-defining plane with the outer end of each impulse piston being contactable by cam means located in the wall interior of housing means of the apparatus, with the inner ends of the pistons entering the hydraulic cylinder for contact by fluid therein.

6. Apparatus as claimed in claim 4 or 5, wherein the cavity is divided into three or more said zones.

7. An apparatus as claimed in claim 4 and 5, wherein the cavity is defined at one end by said end of the mandrel and at the other end by a manifold fixedly positioned in the end of the hydraulic cylinder remote from the mandrel, the manifold having passing therethrough duct means having a check valve for preventing fluid flow therethrough out of the cavity in the hydraulic cylinder.

8. An apparatus as claimed in any one of the preceding claims, wherein the end of the mandrel remote from the hydraulic cylinder is formed as a chute in which there is fitted a throttle ring.

9. An apparatus as claimed in any one of the preceding claims, wherein the mandrel is made of a magnetically soft material.

10. An apparatus as claimed in any one of the preceding claims, wherein the roller means is additionally associated with copying means including a template device for achieving deformation of the blank in accordance with the profile of the template as it undergoes reduction.

11. An apparatus for hydroplastic reduction of tubular blanks, substantially as hereinbefore described with reference to and as shown in Figures 1 to 3 of the accompanying drawings.

12. An apparatus for the hydroplastic reduction of tubular blanks, substantially as hereinbefore described with reference to and as shown in Figures 3 to 5 of the accompanying drawings.