DK143072B - PROCEDURE FOR MANUFACTURING A REMAGNETIZABLE DESIGN PART - Google Patents

Description

(S) (11) PUBLICATION NOTICE 1 ^ 3072 DENMARK '') Intel * c 22 F 1/10 • (21) Application No. 91 6/73 (22) Filed on 21 Feb. 1973 (24) Running day 21 Feb 1973 (44) The application presented and the petition published on 25 Π1 & Γ · 1 981 DIRECTORATE OF THE PATENT AND TRADEMARKET (3 °) Pr, ontet b "* ®" "f ™ on

Feb 22 1972, 227762, US

(71) WESTERN ELECTRIC COMPANY INCORPORATED, 195 Broadway, New York, N.Y., US.

(72) Inventor: Wendel Edward Archer, 468, Anthony Court, Gahanna, Franklin County, Ohio 43250s US: "Karl Martin _01sen, 231 Greenwood Avenue, Madison, Madison County, New Jersey 07g40, US: Paul William Renaut, 6153 # Cherry Hill Drive, Columbus, Franklin County, Ohio 43213 # Us.

(74) Plenipotentiary in the proceedings:

Hofman-Bang & Boutard Engineering Company.

(54) Method of manufacturing a re-magnetizable structural member.

The invention relates to a method of the kind set forth in claim 1.

The "Bell System Technical Journal" January I960 page 1 et seq. Describes a group of switching devices which are distinguished by tightly enclosed metallic contacts which are part of a magnetic switching circuit comprising at least one remanent magnetic part. Remanent magnetic parts, which are generally connected by an enclosing coil winding, have a sufficient remanent magnetization so that the contacts can either be kept in closed or open position without continuous energy consumption.

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The hitherto used constructions of the aforementioned kind comprise a pair of magnetically soft tongues with contact zones which are magnetically coupled to one or more remanent magnetic parts located outside the switch. At the same time as the basic structural members appeared, proposed simplified variants in which the tongues themselves comprised or consisted of magnetic material (see the above article as well as the description for US Patent 3,059,075).

There are many advantages to remanent magnetic tongues. The disposal of the non-contact remanent magnetic parts leads to both economical manufacture and a reduction of tolerance. Tongues with an inherent remanent magnetism can be driven in many ways even with power savings.

Although these magnetic tongues have obvious advantages, they have no commercial significance. In general, the continued manufacture of the uneconomical large structure, which uses outside magnetic shifting parts, attributes certain difficulties in the manufacture of the remanent magnetic tongue. The main difficulty lies in the shaping of the tongue. This shaping is desired to be done by means of a simple press or stamp (comprising precipitation of a circular wire). It has been found that this design frequently leads to a brittle material at risk of rupture when a suitable magnetic material is used.

The above-mentioned technique presupposes the use of an alloy consisting of 50/50 parts of cobalt and iron with a slight addition of vanadium. Providing the desired residue (of the order of at least 1.0 Thesia) comprises one or more curing operations.

From German Patent Specification No. 1,458,521, it is known to use a permanent magnetic alloy for the manufacture of re-magnetizable structural members for re-magnetizable switches which comprises 40-75 wt.% Cobalt, 25-60 wt.% Iron and 1-5% vanadium. and has been tooth-discarded a treatment comprising at least 60% cold rolling and standing at 400 ° C-675 ° C for a time interval of between 1/4 - 25 hours, the shorter time corresponding to the higher temperature.

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This magnetic material is used as a sleeve for self-holding switches and must exhibit a stable coercive force over a large temperature range at a high residual and good rectangle ratio.

SUMMARY OF THE INVENTION The object of the invention is to provide a method which makes it possible to use such magnetic material for the manufacture of the tongues for a switch of the kind mentioned.

This is achieved by performing the method as set forth in the characterizing portion of claim 1. According to the invention, it is cured at 550 ° C-670 ° C, i.e. the upper part of the known temperature range.

By practicing the method of claim 2, a lightly cured wire is obtained which results in the flat tongue portion and the round shaft portion obtaining more uniform magnetic properties.

The invention will be explained in more detail by the following description of an embodiment of an encapsulated contact, reference being made to the drawing, the only figure of which shows an embodiment of such contact.

The figure shows a tongue contact serving as an example of such contacts intentionally made by the method according to the invention. A detailed description of such an apparatus and number of variations is contained in the aforementioned specification of U.S. Patent No. 3,059,075. The figure shows a glass tube 1 containing two tongues 2 and 3, each provided with contact areas 4 and 5, respectively. The majority of each tongues 2 and 3 are flattened from a round thread whose cross-sectional shape is retained in protruding parts 6 and 7. These parts 6 and 7 enter the capsule 1 through glass seals 8 and 9. The apparatus has two separate windings 10 and 11, the first of which, when receiving power from means not shown, will cause the polarization of the tongue 2 in one of the two allowed directions, while the second winding 11 will cause polarization of the tongue 3. This particular arrangement, which in more complicated forms may contain overlapping windings, permits separate control of each of the tongues and is therefore suitable for use in an arrangement of crosspoints.

The operation of the device is very simple. Polarization of the tongues 2 and 3 in the same direction, e.g. north-south from left to right 1 of the figure causes contact closure while magnetizing tongues 2 and 3 in opposite directions, e.g. north-south of tongue 2 and south-north of tongue 3, counted from left to right, causes disruption. As mentioned above, the nature of the residual material contained in at least in part at least one of the tongues 2 and 3 is such that either closed state or interrupted state can be maintained without energy consumption, i.e. the residual magnetization is sufficient to overcome the natural feedback forces in the apparatus.

The apparatus may be modified such that, for example, one of the tongues is made with permanent pre-magnetization, being made of a permamagnetic material which is not switched during operation, or by using a separate pre-magnetizing element, by incorporating a number of additional tongues or contacts or at various circuit arrangements.

Composition of the tongues

It was mentioned that the residual material used belongs to the class of materials commonly referred to as "Remendur". It was mentioned that the full range of composition of the material is from 40 to 75 parts by weight of cobalt, 25 to 60 parts by weight of iron and 1 to 5 parts by weight of vanadium. Various compositions and preferred ranges are disclosed in U.S. Patent No. 3,364,449.

As discussed therein, the nominal and preferred composition consists of approximately equal parts of cobalt and iron, a preferred range of the major constituents being designated as 45 to 65 parts of cobalt, the remainder iron. The preferred range of vanadium serving to determine the coercive force is from 2 to 4 parts by weight, based on 100 parts by weight of the three components, cobalt, iron and vanadium. Other constituents may include manganese intended to reduce the detrimental effect of possible sulfur content, usually up to about weight by weight on the above basis, and possibly less amounts of silicon and aluminum, each in an amount of less than 1 part by weight. These last two constituents serve to bind oxygen which can also be harmful during treatment. In addition to said intended ingredients, there are tolerable amounts of commonly occurring impurities. Such impurities, the total amount of which does not exceed 1 part by weight, may consist of nickel, coal, copper and sulfur.

Treatment A. The remanent magnetic material

The specified blend is referred to as "Remendur" only when it has a medium hardness to obtain a residual magnetization of the order of at least 10,000 gauss. In magnetic soft state, the material is sometimes referred to as "Permendur", while in cured state it is sometimes referred to as "Yicalloy "The development of the necessary force of magnetic hardness requires both cold working and phase precipitation hardening. The present invention is largely based on the particular way in which these processing steps are performed. Although the most crucial processing steps for the invention are the three final steps ( hereinafter referred to as 5 or 5 plus 5A, 6 and 7), the following description indicates appropriate prior steps, beginning with the formation of the alloy itself.

Step 1. A starting material is made of a melt. Suitable materials are electrolytic cobalt, electrolytic iron, ferrovanadium (an alloy of vanadium and iron) and electrolytic manganese. The ingredients are melted, melting temperature and so on. The temperature is kept for a minute or two to ensure thorough mixing, and upon cooling a block is formed.

Step 2. The block undergoes heat deformation at a temperature between 900 ° C and 1250 ° C. Machining may have forums of rolling, forging or extrusion. Treatment is continued to an appropriate dimension, e.g. to a diameter of approx. 6 mm. This step usually includes many passages or connectors.

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Step 5. The heat-processed body is softened by heating to a temperature of at least 750 ° C followed by quenching at such a rate as to avoid appreciable phase precipitation. This is usually done by rapid immersion in ice water (ice brine). Room temperature is reached in less than 1 minute.

Step 4. The cooled rod is cold worked to the desired final dimension (generally cold drawing to a diameter of between 0.025 and 0.125 cm).

Step 5. The first of the special treatments which contribute to the proper preparation according to the invention comprises a strand annealing. During this step, the wire is softened by heat treatment, so as to obtain a tensile strength of not more than H.000 kg / cm and an extension of at least approx. An exemplary treatment is based on maintaining a temperature in a range of approx.

850 ° C to 1050 ° 0. This temperature should be kept for a minimum of at least 5 seconds while the upper time limit is uncritical and determined for practical reasons. In a procedure that is found to be satisfactory, the thread is passed through a hot zone of 1 m length at a speed of approx. 2 m per maintaining a temperature near temperature in the zone for a period of approx. 15 seconds. Immediately after this heating, the wire is passed through a water-cooled chamber, in which it cools down so rapidly as to prevent phase precipitation and associated cure. This step is carried out for a variety of reasons in a reducing atmosphere, e.g. hydrogen or cracked ammonia. Although an inert atmosphere will in principle be permissible, it is more practical for practical reasons to work with a reducing atmosphere than to use the degree of care necessary to exclude minor amounts of oxidizing constituents from conventional "inert" gases. The purpose of the reducing atmosphere, or more commonly the non-oxidizing atmosphere, is to avoid the formation of surface oxide, especially vanadium dioxide, which, by its abrasive action, would cause severe wear of the matrix in the subsequent step 6. The use of such a non-oxidizing atmosphere is also desirable to provide a relatively clean surface for subsequent plating for contact formation as discussed later in Section B.

Step 5a. Although a strand annealing as described - for appliance properties - will be sufficient to prepare the material for cold working during step 6, some practical considerations may require modification. For example, it has been found that the finished tongue exhibits different magnetic properties between the flattened portion bearing the contact surface and the still round portion serving for sealing needle.

For the sake of proper preparation, it may be desirable to treat the tongue so that these properties become more similar. For example, while this will have no definitive effect on the operating characteristics of the apparatus, it may be convenient as a result of such practical considerations as specifying the thread properties of the intermediate to undergo the treatment referred to in step 6. A possible solution in this regard is to use a light cured wire at this step. This can be done, for example. obtained by a cold working after strand annealing in step 5. This cold working, which must be so light that the thread remains within the values of the highest permissible tensile strength, can take the form of a cross-sectional reduction between 20 and 50 $> This treatment must be considered as optional.

Step 6. This is a punch operation. During this step, the round wire from step 5 or step 5 plus step 5a is flattened to form the inner portion of the tongue while retaining the round cross section in the portion to be melted into the glass tube. During this punching, the tongue can also be cut to the desired length. The properties developed in step 6 or the treatment benefits obtained in step 6 relate only to the flattening effect. In the punching operation, a coercive force of about 30 - 60 trout is obtained and a residual magnetization of 7,000 - 10,000 gauss. Further improving the properties, Ted obtains a phase precipitation treatment as described in step 7.

Since the thread produced at the manufacturing steps up to step 5 or step 5a usually shows some curvature, it is usual to correct the thread at this point. As a rule, the thread starting from step 5 or step 5a is first straightened, then flattened and finally cut to the desired length in the order specified. The straightening had little effect on the mechanical and magnetic properties.

A further minor mechanical treatment that can be performed at this time comprises drum cleaning in liquids containing abrasives or other means for removing possible burrs or other surface irregularities produced by the mechanical punching operation.

It has generally been found that the degree of cold working during the punching operation has relatively little effect on the final developed properties. For example, if one starts with a 0.053 cm diameter round wire from which one sample is flattened to 0.013 cm and another to 0.02 or 0.023 cm, no appreciable variation in the final magnetic properties is seen. A thickness reduction of at least approx. $ 40, corresponding to the ratio of the minimum final thickness to the original wire diameter, will suffice at this step to provide the required operating characteristics.

Step 7. The final treatment step comprises phase precipitation at such a temperature for such a period that the desired values of residual magnetization are developed and the cationic force is obtained. In the case of apparatus of the invention, it is generally desired that the residual magnetization is in the range of 10,000 gauss to 20,000 gauss and that the coercive force is in the range of 10 trout to 50 trout. These values apply to both the round and flat parts of the tongue.

It has been found that the said magnetic properties are obtained by heat treating the tongue at temperatures in the range of 550 ° C to 670 ° C for a period of 1/2 to 6 hours. Extensive increments have shown that substantially longer periods of time or higher temperatures will result in a reduction of both the residual magnetization and the coercive force to values below the specified limits. Shorter time or lower temperature mean that higher values of coercive force are retained, but do not produce the desired residual magnetization.

It is discussed above how the protruding portion of the tongue becomes hermetically connected to the capsule. It has been stated that the use of a non-oxidizing or preferably reducing atmosphere in step 5, thereby avoiding the formation of surface oxide, has a beneficial effect in the punching and plating operation. In addition, it has been found that at other processing stages, particularly good hermetic seals are produced. These steps must now be described.

Step 2a. After hot working, the oxide layer is removed either mechanically or chemically. Although conventional strong acid pickling is useful, it has proved most desirable to use mechanical treatment such as grinding or milling. The most important thing here is to get a smooth surface so that the rod can be transformed into wire without surface defects. Such a thread is essential for hermetic sealing since the sealing between the wire and glass seems to be primarily a pressure seal, with no chemical effect.

Step 5a. After quenching it will be found that quite a thin layer of oxide has again formed and this must also be removed, e.g. by sand blasting. Alternatively, pickling can be used. It may be possible to omit step 2a and perform the entire surface cleansing at this step. However, attempts to carry out the entire grinding or milling operation at this stage, however, in some cases resulted in fractures during the cold working of step 4. It is possible that the entire surface treatment may be performed on smaller diameter bars, either produced by further hot rolling as under step 2 or by cold working of quenched rods as in step 4.

Step 3b. Previous experience has shown that "Remendur" treated according to step 3 is susceptible to the required cold drawing or other cross-sectional reduction in cold working without the use of a metallic plating. Cheaper lubrication methods using oil or dry lubricants have generally been considered adequate. However, it has been found that the use of a coating of copper or other soft metal, such as silver or tin, usually applied electrochemically, or alternatively another chemical coating material such as zinc phosphate, borax or inorganic oxalates not only contributes to lubrication, but also provides a protective layer that facilitates the fabrication of wire with a more perfect surface suitable for hermetic sealing. As with the previous practice, such cladding material can be removed, usually by chemical etching, before the last drawing through diamond matrices (as opposed to carbide matrices). This generally corresponds to a diameter of about 0.15 cm. One permissible alternative to this step is to preserve the soft metal plating of copper or another permissible soft metal, while organic cladding like tin or other easily digestible metals must be removed as the final product must be able to withstand a temperature between 600 ° and 1400 ° G at formation of the hermetic seal.

In order to maintain a high degree of surface perfection to optimize the hermetic seal, one or more additional strand anneals may be introduced starting at a diameter of approx. 0.15 cm, to prevent surface scratches. This annealing can be done by passing the thread at a rate of 1 in. minutes pass through a hot zone of 1 m in length, in which temperatures between 250 ° C and 1050 ° C are achieved for about half a minute, followed by passage through a water-cooled chamber for rapid cooling.

B. Contact formation

The contact parts of the tongues are provided with appropriate plating in the usual manner. As a rule, a single layer of hard gold (e.g., cobalt-cured gold produced in a cyanide bath with citrate buffer) will be adequate. The thickness of the plating, which is also not unusual, is not critical and may be in the range of 0.5 to 5 μ. Due to the unusually small dimensions, especially the contact gap of the apparatus, it is usually desirable to maintain uniform thickness within 5 ¢.

C. Canned seal

The second operation that deserves mention here concerns the hermetic seal between the protruding tongue portion and the material in the capsule. The requirements are the same as for seals between glass and metal in other areas. An appropriate coefficient of temperature expansion, which closely corresponds to the corresponding value for "Remendur", can be obtained using lead glass mixtures or other suitable materials. It was mentioned that in general, the compound must be considered as a main seal a pressure seal. The glass material in the capsule is softened by heating and caused to flow around the protruding tongue. Upon cooling, compressive stresses are developed in the sealing region by an intended design, with quite a slight inequality between the expansion coefficients of the glass and the material of the tongue. The best hermetic seals have been produced by the preferred embodiment of the invention, namely by using steps 2a, 3a and 3b.

The temperature sensitivity of the tongues with respect to the desired operating characteristics results in a further requirement for the sealing operation or the melting operation. It has been found that if the tongue is kept at a temperature above ca. 800 ° C, even in the short periods of approx. 6 seconds occurring during the melt-in can reduce the coercive power up to $ 20.