GB1564249A - Pressure piercing and rolling-mill - Google Patents

Description

(54) AN IMPROVED PRESSURE PIERCING AND ROLLING-MILL (71) We, INNOCENTI SANTEUS TACCHIO S.p.A., an Italian joint Stock Company, located at 20 via A. Franchi, Brescia, ITALY, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a pressure piercing and rolling mill, more particularly to an improvement to the inlet guide of a pressure rolling-mill for square bars which are to be simultaneously rolled and axially pierced.

A pressure piercing and rolling-mill, hereinafter indicated by the symbol PPM only, is a machine used for converting square cross-section steel bars into round, axially pierced blanks, the bars coming from a square-bar rolling mill or directly from a continuous casting installation. Such a machine mainly comprises two grooved rolls and a rod or mandrel which extends along the rolling axis and from the outlet side, the rod having a piercing bit coaxially mounted at one end. The square bar is driven against the grooved rolls and the piercing bit so as to be simultaneously pierced in the axial direction and rolled on the rod or mandrel.

An essential condition for obtaining concentric hollow blanks is that the square bars for rolling and axial piercing must have a regular cross-section, the edges being perpendicular and within very narrow tolerances, so that the PPM can be accurately supplied via a suitable inlet guide fitted thereto. At present, the aforementioned condition is obtained by using a rotary calibrating machine positioned upstream of the PPM and adapted to ensure that each square bar, which comes e.g. from a continuous casting installation, is given a rectangular cross-section with equal diagonals and edges having a radius of curvature suitable to be easily engaged by the rolls of the PPM.

A second condition for optimum simultaneous rolling and axial piercing is that the square bar should be conveyed with a sufficient, constant degree of force by the PPM rolls. To meet this condition, the square bar must be free from surface oxides.

At present, this requirement is satisfied by using a "descaling" unit, which is generally disposed upstream of the calibrator to prevent oxides becoming incorporated in the bar.

However, the distance between the descaling unit and the PPM inlet is usually sufficient for secondary oxides to form on the bar in transit, thus counteracting or at least reducing the usefulness of the descaler.

Another disadvantage of the prior art is that the calibrator is an independent unit and is thus driven by a separate motor and has to be operated by separate personnel. In addition, the calibrator has to be provided with its own inlet and outlet guides, to prevent the calibrated bar from being bent, e.g. because of non-uniform temperature along the bar or non-uniform cross-section.

The invention is based on the problem of reducing the distance between the descaler and the PPM to a length which reliably prevents the formation of secondary oxides on the square bar to be rolled and simultaneously pierced, without thereby neglecting the desired operation of calibrating the bar before it is machined on the PPM.

To this end, according to the invention, there is provided a pressure piercing and rolling mill comprising an inlet guide extending coaxially to the direction of motion of a bar which is to be simultaneously rolled and axially pierced, the rolling mill also comprising a pre-guide secured upstream of the inlet guide and extending coaxially therewith, such mill further comprising at least one pair of calibrating rollers secured between the inlet guide and the pre-guide, the rollers defining a calibration orifice extending coaxially to the inlet guide.

According to another feature of the invention, the pair of calibrating rollers is held by the same structure which bears the inlet guide and co-operates therewith to form a unit which can be individually manipulated.

According to a third feature of the invention, the calibrating rollers are idly borne.

The advantages of the invention are as follows: A descaling machine can be disposed in the immediate neighbourhood and upstream of the PPM, thus reducing the distance between the descaler and the PPM to a value which reliably prevents the formation of secondary oxides on the bar.

The square bar is moved through the idle calibrating rollers by the axial pusher which is also used in the PPM, thus avoiding the use of a motor and accessories for operating the calibrating rollers, and saving considerable energy as a result.

The PPM inlet guide is used as an outlet guide for the pair of calibrating rollers, whereas the PPM pre-guide acts as an inlet guide for the aforementioned pair. This results in considerable structural simplifications and in the possibility of substantially reducing the labour required for operating, checking and maintaining the entire machine.

Since the pair of calibrating rollers and the PPM inlet guide form an individually manipulatable unit, another advantage is the speed with which the unit can be replaced by another, separately-prepared unit in the event of a change in calibre, using the normal PPM operaters.

Other features and advantages of the invention will be clearer from the following description of an embodiment of the invention, given with reference to the accompanying illustrative non-limitative drawings, m which: Figure 1 is a diagram of a PPM inlet guide incorporating the improvement according to the invention; Figure 2 is a cross-section along line II - II in Figure 1, and Figure 3 is a section along line III - III in Figure 1; In the accompanying drawings, reference 1 and 2 denote two grooved rolls of a PPM, references 3 and 4 denote the mandrel and associated piercing bit of the PPM, and A denotes the axis for rolling and simultaneous axial piercing, along which a square bar (not shown) is moved, so as to be converted into a round blank.In known manner, the aforementioned movement is produced by a pusher, diagrammatically indicated by 5, which presses the square bar against the tip of piercing bit 4 between the grooves in the rolls 1 and 2.

The general reference 6 denotes a conventional inlet guide of the PPM. The guide substantially comprises four plates or walls 7, 8, 9, 10 disposed to form a tubular duct having a square cross-section and a longitudinal axis coinciding with the rolling axis A.

The walls are adjustably borne by a rigid frame 11 removably held by an upstream portion 100 of the PPM bearing structure.

References 12 and 13 are diagrammaticallyindicated conventional means of adjusting each wall portion 7, 8, 9, 10 relative to the rolling axis A.

In the position immediately upstream of the inlet guide 6, a bracket 101 is secured to the PPM bearing structure 100 and bears a structure diagrammatically indicated by 14 and substantially comprising a rolling frame comprising a pair of conventional idling rollers 15, 16. Rollers 15, 16 together define a calibrating orifice 17 extending coaxially to the inlet guide, i.e. so that its axis coincides with the rolling axis A.

Upstream of frame 14 and coaxially with orifice 17, a pre-guide 18 of the kind conventionally used in PPM machines is secured in conventional manner (not shown). In the accompanying illustrative drawings, pre-guide 18 comprises a Cshaped duct 18a comprising a number of idle rollers 19 forming a bearing surface for a bar.

As clearly shown in Figure 1, pre-guide 18 is the inlet guide of the pair of calibrating rollers 15, 16, whereas the PPM inlet guide 6 is also the outlet guide of the aforementioned pair of cylinders.

Advantageously frame 14 is removably secured to the structure bearing the inlet guide 6, thus combining therewith to form an individually manipulatable unit.

Of course, rollers 15, 16 can be driven if necessary, and of course more than one pair of calibrating rollers can be used for the required calibration.

WHAT WE CLAIM IS: 1. A pressure piercing and rolling mill comprising an inlet guide extending coaxially to the direction of motion of a bar which is to be simultaneously rolled and axially pierced, the rolling mill also comprising a pre-guide secured upstream of the inlet guide and extending coaxially therewith, such mill further comprising at least one pair of calibrating rollers secured between the inlet guide and the pre-guide, the rollers defining a calibration orifice extending coaxially to the inlet guide.

2. A rolling-mill according to Claim 1, wherein the pair of calibrating rollers is secured in a frame secured to the structure which bears the inlet guide and co-operates therewith to form a unit which can be manipulated in one piece.

3. A rolling-mill according to Claim 1 or

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. the rollers defining a calibration orifice extending coaxially to the inlet guide. According to another feature of the invention, the pair of calibrating rollers is held by the same structure which bears the inlet guide and co-operates therewith to form a unit which can be individually manipulated. According to a third feature of the invention, the calibrating rollers are idly borne. The advantages of the invention are as follows: A descaling machine can be disposed in the immediate neighbourhood and upstream of the PPM, thus reducing the distance between the descaler and the PPM to a value which reliably prevents the formation of secondary oxides on the bar. The square bar is moved through the idle calibrating rollers by the axial pusher which is also used in the PPM, thus avoiding the use of a motor and accessories for operating the calibrating rollers, and saving considerable energy as a result. The PPM inlet guide is used as an outlet guide for the pair of calibrating rollers, whereas the PPM pre-guide acts as an inlet guide for the aforementioned pair. This results in considerable structural simplifications and in the possibility of substantially reducing the labour required for operating, checking and maintaining the entire machine. Since the pair of calibrating rollers and the PPM inlet guide form an individually manipulatable unit, another advantage is the speed with which the unit can be replaced by another, separately-prepared unit in the event of a change in calibre, using the normal PPM operaters. Other features and advantages of the invention will be clearer from the following description of an embodiment of the invention, given with reference to the accompanying illustrative non-limitative drawings, m which: Figure 1 is a diagram of a PPM inlet guide incorporating the improvement according to the invention; Figure 2 is a cross-section along line II - II in Figure 1, and Figure 3 is a section along line III - III in Figure 1; In the accompanying drawings, reference 1 and 2 denote two grooved rolls of a PPM, references 3 and 4 denote the mandrel and associated piercing bit of the PPM, and A denotes the axis for rolling and simultaneous axial piercing, along which a square bar (not shown) is moved, so as to be converted into a round blank.In known manner, the aforementioned movement is produced by a pusher, diagrammatically indicated by 5, which presses the square bar against the tip of piercing bit 4 between the grooves in the rolls 1 and 2. The general reference 6 denotes a conventional inlet guide of the PPM. The guide substantially comprises four plates or walls 7, 8, 9, 10 disposed to form a tubular duct having a square cross-section and a longitudinal axis coinciding with the rolling axis A. The walls are adjustably borne by a rigid frame 11 removably held by an upstream portion 100 of the PPM bearing structure. References 12 and 13 are diagrammaticallyindicated conventional means of adjusting each wall portion 7, 8, 9, 10 relative to the rolling axis A. In the position immediately upstream of the inlet guide 6, a bracket 101 is secured to the PPM bearing structure 100 and bears a structure diagrammatically indicated by 14 and substantially comprising a rolling frame comprising a pair of conventional idling rollers 15, 16. Rollers 15, 16 together define a calibrating orifice 17 extending coaxially to the inlet guide, i.e. so that its axis coincides with the rolling axis A. Upstream of frame 14 and coaxially with orifice 17, a pre-guide 18 of the kind conventionally used in PPM machines is secured in conventional manner (not shown). In the accompanying illustrative drawings, pre-guide 18 comprises a Cshaped duct 18a comprising a number of idle rollers 19 forming a bearing surface for a bar. As clearly shown in Figure 1, pre-guide 18 is the inlet guide of the pair of calibrating rollers 15, 16, whereas the PPM inlet guide 6 is also the outlet guide of the aforementioned pair of cylinders. Advantageously frame 14 is removably secured to the structure bearing the inlet guide 6, thus combining therewith to form an individually manipulatable unit. Of course, rollers 15, 16 can be driven if necessary, and of course more than one pair of calibrating rollers can be used for the required calibration. WHAT WE CLAIM IS:

1. A pressure piercing and rolling mill comprising an inlet guide extending coaxially to the direction of motion of a bar which is to be simultaneously rolled and axially pierced, the rolling mill also comprising a pre-guide secured upstream of the inlet guide and extending coaxially therewith, such mill further comprising at least one pair of calibrating rollers secured between the inlet guide and the pre-guide, the rollers defining a calibration orifice extending coaxially to the inlet guide.

2. A rolling-mill according to Claim 1, wherein the pair of calibrating rollers is secured in a frame secured to the structure which bears the inlet guide and co-operates therewith to form a unit which can be manipulated in one piece.

3. A rolling-mill according to Claim 1 or

2 wherein the aforementioned pair of calibrating rollers are idly borne in the frame.

4. A pressure piercing and rolling-mill substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.