US2570547A

US2570547A - Method of and apparatus for electrically heating and upsetting metal rods or bars

Info

Publication number: US2570547A
Application number: US64883A
Authority: US
Inventors: Hanna Merrill Oliver
Original assignee: Individual
Current assignee: Individual
Priority date: 1947-12-18
Filing date: 1948-12-11
Publication date: 1951-10-09
Anticipated expiration: 1968-10-09

Description

M. o. HANNA 2,570,547

METHOD OF AND APPARATUS FOR ELECTRICALLY HEATING AND UPSETTING METAL RODS OR BARS Filed Dec. ll, 1948 ArryllA Patented Oct. 9, 1951 METHOD OF AND APPARATUS FOR ELEC TRICALLY HEATING AND UPSETTING METAL RODS OR BARS Merrill Oliver Hanna, East Malvern, Victoria, Australia Application December 11, 1948,y Serial No. 64,883 In Australia December 18, 1947 7 Claims.

This invention relates to the heating and upsetting of metal rods or bars using electric resistance heating and refers particularly to the upsetting of rods or bars at one end. Rods or bars upset in this manner can be used for the manufacture of various articles, such as, for instance, single-ended spanners, poppet valves, gate bolts and the like.

The invention has for its object the provision of a method and apparatus whereby the end portion of the rod or bar required to be upset is quickly heated to the upsetting temperature while simultaneously therewith the remaining or body portion of the rod is subjected to a slow heating and, after the upset has been performed, the en#- tire length of the rod is heated to forging temperature, all by electric resistance heating.

According to the invention, the rod or bar to be operated on is placed between end contacts on head and tail saddles and a pair of oppositely arranged contacts provided at the side of the rod are brought into engagement with the rod at. a point close to the head saddle end while the tail saddle end is left free. A heavy current is passed through the end portion of the rod between the head saddle contact and the side contacts to quickly heat said end portion to upsetting temperature and, when the metalv of such portion becomes plastic, one of the saddles, preferably the tail saddle, moves inwardly under applied pressure and causes the metal of said end portion to flow or be upset to the required bulbous form.

Simultaneously with the heating and upsetting of the end portion of the rod, the remainingl body portion of the rod between the end contacts and the tail saddle contact is given a slow heating by causing a portion of the current to leak through said body portion. Finally, the side contacts are withdrawn from engagement with the rod and the full current passed through the rod to heat the entire length of the rod to the temperature required for subsequent forging or shaping.

The contacts of the head and tail saddles are connected to a source of heavy low voltage current, such as the secondary winding of a stepdown transformer, and the side contacts are connected to the tail saddle contact through a bridging conductor in which an adjustable resistance or the like is interposed.

When the side contacts are in engagement with the rod, the current passes through the end pore tion of the rod between the head saddle contact and the side contacts and thence through the bridging conductor and adjustable resistance to the tail saddle contact. The resistance partly restricts the iiow of current through the bridging conductor so that some of the current leaks through the body portion of the rod between the side contacts and thev tail saddle contact and so Icauses the slow heating of said body portion simultaneously with the heating and upsetting of the end portion of the rod.

The invention is more fully described aided by reference to the accompanying drawings wherein:

Fig. 1 is a plan View ofthe preferred form of apparatus used in the invention.

Fig. 2 is a diagram illustrating the electrical arrangements and also showing the end of the rod in the process of being upset.

The apparatus as shown in these views cornprises a head saddle I and a movable tail saddle 2. The head saddle carries a contact 3 while the tail saddle carries a contact 4. The metal rod or bar 5 to be operated on is placed between said

end contacts

3 and 4 as indicated by the dotted lines in Fig. 1^.

The contacts :i` and- 4 are connected by flexible conductors 6 to a source of heavy low voltage current such as the secondary winding 'I of a stepdown transformer 8.

The head saddle I is made adjustable to suit the length of theA rod 5" by mounting it on slides 9 and providing a suitable leading screw I0f operated b-y a hand-wheel or theY like (not shown).

The tail saddle 2 is movable to apply the upsetting pressure to the rod 5 and, for this purpose, it is also mounted onthe slides 9 and has pressure applied to it by means of the air cylinder II.

`The head saddle- I carries a pair of oppositely arranged side contacts I2 which are moved into and out of contact with the rodr 5 by means of air cylinders I3 or the like also-carriedv by the head saddle. The side contacts I2 are spaced from the contact 3 accord-ing to the quantity of metal required to be upset at the end of the rod and suitable means may be provided for adjusting this distance.

Connected to theside contacts I2 are adjust.- able resistances I4 each consisting of a copper coil I5- which may be tubular for water cooling. The coils are tapped as required by means of tapping members I6- connected by flexible bridging conductors Htc the-tailfsaddlefcontact 4.

In use, the rod 5l tol be upset is placed between and gripped by' the end contacts 3 and 4f and the sider contacts I2 moved* inwardly into engagement with the rod. The heavy current from the transformer thus passes through the short end portion I8 of the rod' between the head saddle contact 3y and the side contacts I2 and thence through the adjustable resistances I4 and bridging conductors I'I to the tail saddle contact 4. The short end portion I8 of the rod is thus rapidly heated to plastic state whereupon the tail saddle 2 moves inwardly under its applied pressure to cause the metal of said heated end portion I8 to flow or be upset to bulbous form as shown in Fig. 2.

During the end heating and upsetting operation not all of the current is carried by the bridging conductors II but, due to the restriction oered by the resistances I4, some of the current leaks through the main body portion I9 of the rod between the side contacts I2 and the tail saddle contact 4 and thus gives this portion of the rod a slow heating simultaneously with the heating and upsetting of the end portion I8.

On the completion of the upset, the side contacts I2 are withdrawn from the rod. The full current then passes through the whole length of the rod to heat the entire rod to the requisite temperature ior forging or shaping.

By the method of heating described, considerable economy is secured. The slow heating of the body portion I9 of the rod simultaneously with the heating and upsetting of the end portion IB enables the whole rod to be quickly heated to forging temperature after the upset has been completed and the side contacts I2 are withdrawn. Moreover, with the continuous sequence in the heating as described, the residual heat in the upset portion I8 of the rod is not dissipated but is retained in the heating of the Whole rod to forging temperature.

It will, of course, be obvious that the amount of current allowed to leak through the body portion I9 of the rod can be controlled by adjusting the resistances I4. rl`hus, the temperature to which the preliminary heating of the body portion I9 of the rod is carried can vbe conveniently controlled. Likewise, the resistances I4 can be adjusted as required to suit the length and the gauge or diameter of the rod being upset, and other requirements.

Although two bridging conductors I'I and adjustable resistances I4 are described herein and shown in the drawings, it will be appreciated that only a single bridging conductor and resistance may be used, although the above dual construction is generally preferred.

If desired, the head saddle Contact 3 may be constructed to progressively recede in the manner known in the art of upsetting as the metal in the upset end I8 of the rod increases. This will enable a greater quantity of metal to be upset f into the bulbous end.

What I claim is:

1. In the heating and upsetting of metal rods or bars using electric resistance heating, the method which consists in placing the rod between end contacts on head and tail saddles, moving side contacts into engagement with the rod at a point close to the head saddle end while the tail saddle end remains free, passing heavy low Voltage current through the end portion of the rod between the head saddle contact and the side contacts to heat the metal of said end portion to plastic state, moving one of the saddles inwardly under applied pressure to cause the plastic metal to ilow or be upset to bulbous form, simultaneously giving the remaining body portion of the rod between the side contacts and the tail saddle contact a slow heating by causing a portion of the current to leak through said body portion while the end portion is being heated and upset,

and nally withdrawing the side contacts from engagement with the rod to allow the full current to pass through the whole length of the rod to heat the entire rod for a succeeding operation.

2. An apparatus for heating and upsetting metal rods or bars using electric resistance heating comprising a head saddle and a, tail saddle each having a contact between which the rod is placed, side contacts adapted to engage the rod at a point close to the head saddle end while the tail saddle end remains free, means for moving said side contacts into engagement with the rod and out of engagement with the rod, means for passing heavy low voltage current through the end portion of the rod between the head saddle contact and the side contacts while the latter are engaged with the rod to heat said end portion to upsetting temperature, means moving one of the saddles inwardly to cause the metal of the heated end to iiow or be upset to bulbuous form, and means causing a portion of the current to leak through the remaining body portion of the rod to give such portion a slow heating simultaneously with the heating and upsetting of the end portion, the withdrawal of said side contacts from engagement with the rod causing the full current to pass through the whole length of the rod.

3. An apparatus as claimed in claim 2 including a source of heavy low voltage current and wherein the contacts of the head saddle and tail saddle are connected to said source of heavy low voltage current, said side contacts being connected to the tail saddle contact through a bridging conductor and an adjustable resistance in said bridging conductor, the restriction offered by the resistance causing some of the current to leak through the body portion of the rod between the side contacts and the tail saddle contact to give such portion of the rod the slow heating simultaneously with the heating and upsetting of the end portion.

4. In the heating and upsetting of metal rods or bars using electric resistance heating, the method which consists in placing the rod between end contacts on head and tail saddles, moving side contacts into engagement with the rod at a point close to the head saddle end while the tail saddle end remains free, passing heavy low voltage current through the end portion of the rod between the head saddle contact and the side contacts to heat the metal of said end portion to plastic state, moving one of the saddles inwardly under applied pressure to cause the plastic metal to flow or be upset to bulbous form, and finally withdrawing the side contacts from engagement with the rod to allow the full current to pass through the whole length of the rod.

5. An apparatus for heating and upsetting metal rods or bars using electric resistance heating comprising a head saddle and a tail saddle each having a contact between which the rod is placed, said contacts being connected to a source of current side contacts adapted to engage the rod at a point close to the head saddle end while the tail saddle end remains free, means for moving said side contacts into and out of engagement with the rod, means for passing heavy low voltage current through the end portion of the rod between the head saddle contact and the side contacts while the latter are engaged with the rod to heat said end portion to upsetting temperature, means moving one of the saddles inwardly to cause the metal of the heated end to flow or be upset to bulbous form, the disengagement of said side contacts from engagement with the rod causing the full current to pass through the whole length of the rod.

6. An apparatus as claimed in claim 5, wherein the contacts of the head saddle and tail saddle are connected to said source of heavy low voltage current, said side contacts being connected to the tail saddle contact through a bridging conductor, and an adjustable resistance in said bridging conductor.

'7. An apparatus for heating and upsetting metal rods or bars using electric resistance heating comprising a head saddle and a tail saddle each having a contact between which the rod is placed, side contacts adapted to engage the rod at a point close to the head saddle end whilel the tail saddle end remains free, means for moving said side contacts into engagement with the rod and out of engagement with the rod, means for passing heavy low tolta-ge current through the end portion of the rod between the head saddle contact and the side contacts while the latter are engaged with the rod to heat said end portion to upsetting temperature, means moving one of the saddles inwardly to cause the metal of the heated end to flow or be upset to bulbous form, and means causing a portion of the current to leak through the remaining body portion of the rod to give such portion a slow heating simultaneously with the heating and upsetting of the end portion.

MERRILL OLIVER HANNA.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 1,752,598 Jorgensen Apr. 1, 1930 2,006,459 Jones July 2, 1935