US2968711A - Heating a portion of a profile - Google Patents

Description

Jan. 17, 1961 G. ZUPPIROLI HEATING A PORTION OF A PROFILE 4 Sheets-Sheet 1 Filed April 1, 1959 Jan. 17, 1961 G. ZUPPIROLI 2,968,711

HEATING A PORTION OF A PROFILE Filed April 1, 1959 4 Sheets-Sheet 2 Jan. 17, 1961 G. ZUPPlROLi HEATING A PORTION OF A PROFILE 4 Sheetls-Sheet 5 Filed April 1, 1959 llli'll Jan. 17, 1961 G. ZUPPIROLI 2,968,711

HEATING A PORTION OF A PROFILE Filed April 1, 1959 4 Sheets-Sheet 4 Fig.6

United States Patent HEATING A PORTION OF A PROFILE Guido Zuppiroli, Milan, Italy, assignor to Innocenti Soc. Generale per llndustria Metallurgica e Meccanica, Milan, Italy Filed Apr. 1, 1959, Ser. No. 803,390

Claims priority, application Italy May 27, 1958 1 Claim. (Cl. 219-10.61)

The main patent concerns a device for heating a portion of limited length of a workpiece of elongated shape performing a substantially uniform motion in its longitudinal direction, comprising a plurality of electrical inductors, each of which is adapted to heat a portion of limited length of the workpiece, so arranged as to suecessively act on the workpiece on movement of the latter, means for energizing the said inductors successively in synchronism with the displacement of the workpiece to cause them to constantly operate on the same portion of limited length of the workpiece for the purpose of heating it.

Such devices, which will be hereafter and in the claim referred to as device of the type specified, is described in US. Patent No. 2,822,453, published February 4, 1958.

This invention provides a device of the type specified which is very simple in concept and construction and reliable in working.

The improved device provides for feeding the electrical inductors an alternator feeding the inductors through a rotary commutator including a brush electrically connected with the alternator output, cooperating with a plurality of stationary contacts, each of which is connected to one of the inductors, the said brush being rotated at a speed proportional to the workpiece feed means to cause the inductors to constantly act on the same portion of the workpiece for the purpose of heating it, the device moreover comprising means for cutting out the inductor feed current as the brush is about to leave a stationary contact and contacts the next one.

Further characteristic features of this invention will be understood from the appended detailed description referring to the accompanying drawings, given merely by way of example, wherein:

Figure l is a perspective overall view of the device,

Figure 2 is a detail view of Figure l on an enlarged scale,

Figure 3 is a part diagrammatical plan view of the device,

Figure 4 shows the wiring diagram of the device,

Figure 5 is a part axial sectional view of the rotary commutator and Figure 6 is a detail part view of the wiring diagram shown in Figure 4.

On the drawings 2 generically denotes the workpiece, such as an iron tube movable on rollers 2a carried by a supporting frame.

The workpiece 2 is delivered by a rolling mill 1 to the improved device for the purpose of heating spaced portions thereof. The workpiece issuing from the heating device is caught by a pair of rollers in the manner disclosed by the main patent, the said rollers drawing the heated portion thereby dividing the workpiece into sections.

The heating device generally comprises a high-frequency generator 8 controlled by a modulator 9, the function of which shall be explained hereafter, the generator a conductive ring 12 secured to a rotor 12a splined in turn on a shaft 21.

The rotor 12a is moreover provided with a pair of brushes 13 carried by two radial arms 13a fast with the rotor, the brushes 13 being electrically connected with the ring 12. The brushes close the circuit on a plurality of stationary contacts 22 arranged in a circular row.

The stationary contacts 22 are each connected by a wire 23 to a high-frequency transformer 24 feeding an inductor 25 (heating coils).

The high-frequency transformer 24 and inductor 25 form a unit adapted to concentrate on the workpiece 2 the whole electric power from the high-frequency generator 8, thereby effecting by induction a localized heating of the workpiece.

The shaft 21 carrying the rotor 12a is rotated by an electric motor 7 at a speed proportional to the workpiece feed, the arrangement of the stationary contacts 22 and inductors 25 being moreover such that on operation of the device the operative inductor constantly acts on the same portion of the workpiece for the purpose of heating it.

The motor 7 is operated through a control and adjusting equipment 5 by speed adjusting dynamos 4 running at a speed of its own, linked through the feeler wheel 3 to the movable workpiece 2.

According to a further feature of this invention opening and closing of the circuits through the brush 13 and stationary contacts 22 cannot be effected under load by virtue of means adapted to cut out the current feeding the inductors as the brush is about to leave a stationary contact and contact the next one. The cutout means comprises a lamp 19, the light rays from which are concentrated to a parallel beam 20 on a photoelectric cell 18 acting on the modulator 9, means adapted to intercept light from the lamp being arranged in the path of the light rays.

The intercepting means comprises an annular screen 16 secured to the rotor 12a, the annular screen 16 being formed with an aperture 17 which, when it is brought within range of the rays 20 causes the latter to strike the photoelectric cell 18. The signals from the photoelectric cell are conveniently amplified by the modulator 9 and control the high frequency generator 8 by biasing its grid.

By way of example, the circuit of the photoelectric cell and modulator 9, of a type known per se, could be carried out as shown in Figure 6.

In this figure, 19 still denotes the energizing lamp, 18 the photoelectric cell having a potentiometric circuit, the photoelectric cell being fed through a double half-wave rectifying tube 26.

The output current from the photoelectric cell is amplified by a first amplifying stage comprising a tetrode 27 fed by two rectifying diodes 28. The output signals from the first stage are amplified by an end amplifier triode 29 having the high-frequency generator connected across its output 30. 31 denotes two rectifying diodes feeding the end stage.

The modulator is fed with alternating voltage supplied by a network 32 and includes feed transformers T, signalling lamps S and further known circuit components.

What I claim is:

In the device of the type specified, the means for energizing the inductors in synchronism with the displace- Pat'ented Jan. 17, 1961 ment of the workpiece comprising a high-frequency current generator; a rotary commutator including a rotary distributor brush operatively connected to the output of the generator and a circular series of stationary contacts successively engaged by the brush on rotation of the latter, the successive contacts being electrically connected to the successive inductors whereby the latter are successively energized on rotation of the brush; means sensitive to the speed of the workpiece controlling the rotary movement of the brush thereby to energize the successive inductors in synchronism with the displacement of the workpiece; and control means associated with the generator for blocking the latter every instant in which the brush is about to leave a contact, the said control means comprising a photoelectric cell-controlled modulator open-- References Cited in the file of this patent UNITED STATES PATENTS 1,981,631 Northrup Nov. 20, 1934 2,404,147 Strickland 2. July 16, 1946 2,822,453 Zuppiroli t. Feb. 4, 1958 2,829,229 1958 Metz Apr. 1,

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