Method to manufacture wire measurement resistor. RU patent 2504035.

FIELD: electricity.

SUBSTANCE: place of their connection is divided with a frame at the ratio close according to the proposed ratio of temperature resistance coefficients (TRC) of materials of sections wire produced by temperature characteristics of annealing. The temperature dependence of resistance is adjusted by means of winding the wire off the frame. They perform thermal treatment of the resistor to produce the specified TRC of resistive sections of various sign, adjusting the mode of thermal treatment. They determine the ratio of the TRC values in sections and alternate winding of wire off them, using intermediate measurements of section resistances, they provide for compliance with the following ratios: R=R1+R2, where α₁ α₂ - TRC of sections; R1, R2, ρ_1; ρ₂ - their electric and specific resistances; n, m - number of turns in the first and second sections; R - total electric resistance of the resistor, so that in process of winding to preserve the established proportion of section turns, providing for the TRC of the resistor equal to zero and bringing its total resistance to the nominal value.

EFFECT: achievement of low absolute value of resistor's TRC and high accuracy of finalisation of its resistance to nominal value with simplification of the method for resistor manufacturing.

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The invention relates to electronic engineering and may be used in the production of precision wire-wound followed by manufacture on their basis of measuring transducers of high precision.

Known precision wire resistors (PR) of various types [1]. The disadvantage of all known according to [1] precision wire resistors are sufficiently high values of the temperature coefficient of resistance (TCR) and its instability in the operating temperature range.

Known wire resistor [2]. The disadvantage of this design PR is a relatively high complexity of manufacturing, as well as insufficient to compensate TKS due to the complexity of selection of resistive conductors of various diameters with the same, but opposite in sign of TCS in the operating temperature range.

As a prototype chosen method of manufacturing resistors [3], which includes the following operations: winding wire resistive on a cylindrical frame consisting of two parts, the main and additional, made of materials with different values of temperature coefficient of linear expansion, determination of values and TKS nonlinearity of the temperature dependence of the resistance?, adjust the values of β by twisting the part of wire with an additional or main part of the frame several times successively, with intermediate removing the characteristics of the relative change in resistance in the temperature range to obtain optimum performance and adjustment of the value of the resistor to the nominal value of produce after adjustment of the nonlinearity.

The disadvantage of this method of manufacturing PR is its high complexity and differentiation of adjustments to the values of beta and its impedance lead to an increase of the absolute value of the TCS wire wound resistor.

The objective of the invention is to simplify the process of manufacturing of the measuring resistor, achieving low absolute values of its TCS and high precision finishing his resistance to the nominal value.

The task is achieved by way of manufacturing of wire measuring resistor includes winding wire resistive on a cylindrical frame and adjusts the characteristics of the temperature dependence of the resistance by twisting the wire frame. Winding on a cylindrical frame produce two sections of different types of wire resistive that frame electrically connect the metal clamp, and the place of their connection divides the frame in relation to close the absolute value of the expected attitudes TKS materials wire partitions, obtained previously on annealing temperature characteristics, then perform heat treatment resistor, in seeking to achieve a given TKS resistance sections of different sign, adjusting the mode of submission of heat treatment on the treated resistor current, a variation of which determine the optimal mode of heat treatment, and then determine the ratio of the TCS resistance sections, and alternate with them wire using the intermediate resistance measuring data sections, provide performance ratios:

where a 1 , a 2 - TKS relevant resistive sections; R1, R2, ρ 1 , ρ 2 - electrical and specific resistance; n, m - number of turns of the first and second sections accordingly; R - the complete electrical resistance of the measuring resistor, - so that when coiling maintain the established proportion turns sections, providing TKS of the measuring resistor equal to zero and bringing it impedance to the nominal value.

1 is a wire resistor.

Wire resistor consists of ceramic frame 1;

metal caps 2, of the windings of the 3 and 4-wire resistive, having TKS - a 1 and a 2 respectively; metal conclusions 5; metal strap 6; L - length of ceramic frame; L1 - length part of the ceramic frame to the metal buckle 6, made, for example, of aluminium.

Figure 2 shows the graphical dependence TKS wire of some chromium-Nickel (Cr-Ni) materials, depending on the temperature of the heat treatment (annealing) T .

Figure 7 shows the dependence of TKS from T wire of a material 701087, graphics 8-11 respectively 2073, 70, 23, 80.

Figure 3 presents electric scheme provides a fitting parameters of the manufactured measuring resistor (aggregate measurement resistor resistance R is equal to: R=R1+R2).

Electrical circuit of figure 3 consists of a controlled source of a stable DC 12, voltmeter 13, switch metering modes 14, probe electrode 15, and terminals is 16.

Distinctive features of the declared method of manufacture of a wire measuring resistor compared with the prototype are:

1. The design of the proposed precision wire resistor easier as its frame is divided into 2 parts, made from various materials and requiring various manufacturing technology.

2. Adjusting method is easier and more accurate, as in the proposed method, the fitting of the TCS and the nominal value of the resistor is carried out in a single cycle, unlike the prototype method.

The essence of the invention is illustrated by drawings figure 1-2.

Frame 1 resistor made of ceramic, which has a temperature coefficient of linear expansion (TCLE) 5 x 10 -6 grad -1 . On frame 1 metal caps 2 with metal pins 5. Wound wire resistive with TCS - alpha 1 on the part of the ceramic frame length L1, providing electrical contact with one of the conclusions of 5 and clamp 6, made, for example, of aluminium.

Heat treatment is a common operation for stabilization of electrical properties of resistors. Change TCS, resistance and stability resistive wire annealing associated with the different degree of crystallization (ordering of structure). This is also connected with a change of internal stresses in it, including those arising in the process of winding on the frame, oxidative processes, taking place both inside and on the surface of a resistive wire annealing of defects, stabilization pin knots.

The graphs in figure 2 shows the experimental dependencies of TKS resistive wire from five different Cr-Ni alloys used in the production of resistors. As follows from the above graphs and mathematical point of view, the most high stability TKS depending on annealing temperature T falls on the treatment temperature, located on the excesses characteristics, i.e. the points of the function extremums TKS (T ).

In turn, when the flow through the resistors operating currents is their self heating due to the selection of resistors active power: P=I 2 R.

As a result of laboratory tests has received the following experimental table 1.

The tabular factor is determined by the expression:

where P is a fact - the actual power dissipation, and P nom - nominal power dissipation resistor. As follows from table 1, for resistors with a capacity of scattering equal to, for example, 1 watt when applying the rated load temperature on the housing of the resistor reaches 75C C. it was found also that the temperature of the resistive element is much higher, at 90°C.

Parallel or series connection of resistors is a resistive structure, which has its own TCS and which can be calculated [4; 5]. For serial connection of two resistor with resistance R 1 and R 2 temperature coefficient of resistance patterns is:

where a 1 , R1, a 2 , R2 - TKS and resistance respectively the first and second resistor, a, R - TKS and resistance consistent framework (comprehensive resistor).

Suppose lim α = 0, then

but this attitude cannot be negative due to the physical properties of the electrical resistance of the resistor, i.e. the ratio can be satisfied if the signs TKS α 1 and C 2 opposite.

The layout and graphics presented in figure 2 suggest a method of manufacturing of precision resistor consisting in the following.

The ceramic frame 1 metal caps 2 with the conclusions of 5, reel up with some margin wire 3 from the first resistive material on the part of the L-L1 ceramic frame and attach one end to the first pin 5 of the resistor, and the other end to a metal collar 6 installed at the distance of L-L1 from the edge of ceramic frame. Reel up also with some margin wire 4 from the second resistive material, TKS which after heat treatment will have the opposite sign TKS first resistive material, the second part of L1 ceramic frame, and the first end of a wire 4 is connected to the second terminal 5, and the second to a metal collar 6. The dependencies TKS (T ) determine the optimal mode of annealing, guided types of resistive wire and characteristic points dependencies TKS (T ), where for two selected materials TKS T ) have different signs and are either flat sections, or extreme points. Then resistor placed in the chamber, the temperature in which establish a less than optimal on the value of the self-ignition temperature at rated operation mode resistor, through which pass the rated current. After annealing measure TKS two resistive plots resistance R1 and R2, using, for example, the electrical circuit of figure 3, and then periodically conducting measurements, perform adjustment of the impedance by resistive wire with one end of the resistor, and with another, using the calculated ratios:

From a mathematical expression (2), the following formula:

where n and m - the number of turns on the areas L-L1 L1 and resistor, r - radius turns of wire resistive, which is the same for both sites (unlike the original), ρ 1 and ρ 2 - specific resistance of the resistor plots, A 1 And 2 - section of the first and second resistance of the conductor. Assuming that the radius r of turns is the same everywhere, as shown in the drawing figure 1, and A 1 =2 , we obtain a simplified formula:

As a result of thermal linear expansion of ceramics frame the value of r is , but this does not affect the calculation formulas (2-4), therefore, does not lead to errors in the process of tuning the parameters of the resistor.

Electrical circuit of figure 3 can be used to measure parameters of separate parts of the resistor R1 and R2, as well as installation of the optimal regime of the fitting, adjustable current controlled source 12. The scheme is simple and does not need additional description. All measurement is reduced to the following: set the current source 12, close to the nominal one, using the 14 measured with a voltmeter 13 voltage relevant resistive sites and determine the resistance R1 and R2. Give currents in the range of 20-25 % of the nominal value and determine the increment PTC resistors R1 and R2. Known in EQ TCS at the initial stage thermal treatment establish a mode of annealing.

For example, use experienced dependence TKS (T ) (figure 2) for the five types of varieties resistive wire: 701087, 2073, 70, 23, 80. The graphs 7-11 (figure 2) select two of the material, having in the close area at characteristic zone of stability TKS, with a different sign. It is seen that they are graphs 9 and 11 to the field DT €[400; 480]°N Graph 11 in this area is a point of inflection, parabolic type of extremum, with a small change in the TCS, and schedule 9 is simply the relative stability of the dependence of the TCS (T ), and wire materials 70 and 80 have in the field DT €[400; 480]°With the temperature coefficients of her and I are of opposite sign, which practically does not change the process of cooling of materials at the end of the annealing. Setting the temperature of the heat to 400 OC and placing it partially made resistor is connected to the schema, as shown in figure 3, include a power supply 12 and in a range(20-25) % of nominal current through the resistor define a point with a minimum variation of the TCS and wire of a material 70, and a wire of a material 80. As a material in the production of metal strap prototypes used A1, as a DC source device IPT-5, as a measuring voltmeter - high precision digital voltmeter B1-18.

After heat treatment, the resistor in the optimum from the point of view of stability of TKS mode, execute in a single cycle finishing his TCS and to zero and impedance adjustment to the nominal value, using the calculated ratios (1, 2), alternate winding excess wire from both ends of the resistor and by conducting periodic measurement resistors R1, R2.

Thus, the use of the proposed method ensures the significant (compared with the prototype) reducing the complexity of the manufacturing of precision resistors, and also allows the measurement resistors with PTC Hz 0.1 to 0.5)x 10 -6 grad -1 in the interval of temperatures from +20 to +80 degrees and, in addition, provides high accuracy with the accuracy of manufacturing of the nominal value is not more than + 0,005%.

Sources of information

1. Buts VP Permanent precision wire resistors. Improvement of TCS / VP Buts, I. Filippov, V. M. Telegin // Electronic industry. - M: "CNII ELECTRONICA, 2001. - №4. - P.19-21.

2. A.S. №517944 USSR, H01C 3/00. Wire resistor / SCI Avvakumov, L.P. Kernitsky and . - Publ. 1976, bul. №22.

3. A.S. 1667548 USSR, 01 17/00. A method of manufacturing resistors / G.S. Kuznetsov and V. Isaev. - Publ. 1988, chipboard.

4. Patent of Russian Federation №2208256, 01 17/22. A method of manufacturing of thin film resistor / G.S. Vlasov A.N. Luhin. - Publ. 2003, bul. №19.

5. Vlasov G.S. Research of metrological characteristics of thin-film chips and development of methods and means of their functional fit, and control: the Monography. Part 1. - Penza: Ed.-in . state University, 2003. - 280 C., Pp.138-144; P.98-101.

Method of manufacture of a wire measuring resistor, including winding wire resistive on a cylindrical frame and adjusts the characteristics of the temperature dependence of the resistance by twisting the wire frame, wherein the wound on a cylindrical frame produce two sections of different types of wire resistive that frame electrically connect the metal clamp, and the place of their connection divides the frame in relation to close the absolute value of the expected attitudes of the temperature coefficient of resistance (TCR) materials wire sections obtained previously on annealing temperature characteristics, then perform heat treatment resistor, in seeking to achieve a given TKS resistance sections of different sign, adjusting the mode of submission of heat treatment on the treated resistor current, a variation of which determine the optimal mode of heat treatment, and then determine the ratio of the TCS resistance sections, and alternate with them wire using the intermediate resistance measuring these sections provide the ratio R=R1+R2;

where a 1 , a 2 - TKS appropriate resistance sections; R1, R2, ρ 1 , ρ 2 - electrical and specific resistance; n, m is the number of turns of the first and second sections, respectively; R - the complete electrical resistance of the measuring resistor, - so that when coiling maintain the established proportion turns sections, providing TKS of the measuring resistor equal to zero and bringing it impedance to the nominal value.