RU2312427C2 - Device for fixing parts by way of freezing - Google Patents

Abstract

FIELD: thermoelectric engineering.

SUBSTANCE: proposed device has pipeline divided by means of control unit into three coolant circulation loops. First loop is brought in thermal contact with part, Two other loops are joined with thermoelectric batteries. One of these batteries is designed for cooling and other one, for heating. Control unit couples two loops into single channel and affords flow of either cooled or heated coolant within channel. Thermoelectric battery has alternating p and n branches connected into electric circuit by means of keyboards. Butt-end surface of p branch contacts one of keyboard surfaces and n branch contacts other one. Ends of keyboards protrude beyond surface of structure formed by thermoelectric battery branches. T-section leads of keyboards are soldered to insulated pads made in the form of metal or alloy films applied to ceramic boards.

EFFECT: enhanced effectiveness and reliability of fixation.

1 cl, 2 dwg

Description

The invention relates to thermoelectric technology, in particular to the design of thermoelectric devices for fastening-based parts by freezing during machining.

The prototype of the invention is a freezing device designed to fix parts during processing on machines by freezing [1]. The device includes a thermoelectric battery (thermopile), brought into thermal contact by cold junctions with the part to be machined, and a liquid heat exchanger associated with hot junctions of the thermopile.

The thermopile is made of semiconductor thermoelements connected in series to an electric circuit, each of which is formed by two branches (columns made either cylindrical or in the form of a rectangular parallelepiped) made of a p- and n-type semiconductor, respectively. The branches of thermocouples are interconnected by means of patch plates, moreover, the switching of both branches (p- and n-type) to the patch plate is made to the same flat surface along the edges of the latter. In this case, the thermocouple has a "U-shaped" shape, where the vertical elements are p- and n-branches, and the horizontal ones are patch plates. Thermoelements that form thermopiles electrically connected in series by switching plates are enclosed between two highly heat-conducting electrical insulating heat transfer plates.

A disadvantage of the known design is the inability to use powerful thermopiles with a supply current of about 100 A and higher due to the occurrence of significant mechanical stresses in this thermopile design due to the thermal expansion (compression) of materials, as well as the bimetallic effect, which reduce the reliability of its functioning and baseline accuracy to almost zero details. This circumstance limits the applicability of this device for freezing large parts and small parts in large quantities during their machining with high intensity.

The aim of the invention is to remedy these disadvantages.

The goal is achieved in that the thermopile is coupled with the part by means of a pipeline, divided by the control unit into three coolant circuits, the first circuit being brought into thermal contact with the part, and each of the other two circuits is mated with the thermopile, respectively, one of the thermopile functioning in cooling mode, and the second in heating mode. In this case, the control unit communicates the circuits one and two, or one and three into a single channel and ensures that either cooled or heated coolant flows in the channel. Each thermopile is composed of alternating branches connected in series to the electric circuit by means of patch plates, respectively made of p- and n-type semiconductor, the electrical connection of the branches is carried out by means of the p-type branch-connection plate-n-type branch, where the p- branch type contacts the end surface with one of the surfaces of the patch plate, and the n-type branch with the other. In this case, each branch in the thermopile is in contact with opposite end surfaces with two switching plates, and the connecting plates have an area slightly larger than the cross-sectional area of the p- and n-type branches, as a result of which their ends protrude beyond the surface of the structure formed by the thermopile branches. The ends of the connecting plates making cold contacts protrude beyond one surface of the structure, and the ends of the connecting plates making hot contacts protruding from the other, and the free ends of the connecting plates are made with a T-shaped cross section and are soldered to electrically insulated areas made in in the form of films of metals or alloys deposited on ceramic plates.

The design of the device for mounting parts by freezing is shown in figures 1 and 2.

The device includes a pipeline 1, divided by a control unit 2 into three coolant circulation circuits 3, 4, 5. The coolant circulation circuit 3 is brought into thermal contact with the freezing object (part) 6, and circuits 4 and 5 are interfaced with the thermopile, 7 and 8, moreover, one of the thermopiles is designed to operate in cooling mode, and the second in heating mode. The control unit 2 communicates circuits 3 and 4 or 3 and 5 into a single channel and ensures that either cooled or heated coolant 9 flows in the channel.

TEB 7 (8) consists of alternating branches connected in series into an electric circuit by means of switching plates 10 and 11, made of p-type 12 and n-type semiconductor, respectively. 13 Electrical connection of branches is carried out by means of a p-type branch 12-switching plate 10 or 11-branch of n-type 13, where the branch of p-type 12 is in contact with the end surface from one of the surfaces of the patch plate, and the branch of n-type 13 is on the other. Each branch in the TEB 7 (8) contacts opposite end surfaces with two switching plates 10 and 11. The switching plates 10 and 11 have an area slightly larger than the cross-sectional area of the p- and n-type branches 12 and 13, as a result of which their ends protrude beyond the surface of the structure formed by the branches of the thermopile elements 7 (8), as shown in Fig.2. The ends of the connecting plates 10, carrying out cold contacts, protrude beyond one surface of the structure, and the ends of the connecting plates 11, carrying out hot contacts, beyond the other. The free ends of the connecting plates 10 and 11 are made with a T-shaped cross section and are soldered to the areas 14 and 15 electrically insulated from each other, made in the form of metal or alloy films deposited on ceramic plates 16 and 17. On the extreme end surface of the branches, respectively at the beginning and end of the fuel and energy complex 7 (8), there are contact pads 18, through which electric energy is supplied to it.

The device operates as follows.

When the device is operating in the freezing mode of part 6, the control unit 2 communicates circuits 3 and 4 into a single channel through which the coolant 9, cooled by the thermopile, 7 flows.

Cooling the coolant 9 is as follows.

When passing through the thermopile, working in the cooling mode (for example, thermopile 7), a constant electric current supplied from the electric energy source through the contact pads 18, between the switching plates 10 and 11, which are the contacts of the p- and n-type branches 12 and 13 , a temperature difference arises due to the release of Peltier heat at other neighboring ends of the branches and absorption at the other neighboring ends of the branches. With the polarity of the electric current indicated in FIG. 2, the patch plates 11 are heated and the patch plates 10 are cooled. Accordingly, the pads 15 and the ceramic plate 17 are heated and the pads 14 and the ceramic plate 16 are cooled. The coolant 9 is cooled to the required temperature when flowing through pipeline 1 along the ceramic plate 16. Heat is removed from the ceramic plate 17 by means of a heat transfer system (not shown in FIGS. 1 and 2). The freezing of the part 6 is due to its thermal interface with the cooled coolant 9 flowing in the channel formed by regions 3 and 4.

At the end of the machining of part 6, it is removed from the working surface. The removal of part 6 is carried out with an increase in its temperature by the coolant 9 flowing in the channel formed by the regions 3 and 5 connected by the control unit 2 and the heated thermopile 8.

The heating mechanism of the heat carrier 9 of thermopile 8 is similar to its cooling of thermopile 7. The difference is in the reverse direction of the supply current flowing through the thermopile 8, in relation to the thermopile 7.

In the inventive device for mounting parts by freezing:

1) mechanical stresses arising in the branches of p- and n-type thermoelements due to the linear compensation of thermal expansion of one ends of the (hot) branches by linear compression of the other ends (cold) are partially or completely eliminated, which leads to increased reliability of the thermopile

2) to a large extent, heat flows from hot patch plates to cold are eliminated through inter-element spaces due to their denser packing;

3) connection plates due to the specifics of the performance of the electrical contacts of the thermopile, have a much smaller thickness than in the prototype, the consequence of which is a significant decrease in their electrical resistances and heat capacity, which makes it possible to achieve lower temperatures, and also reduces the duration of the thermopile on the operating mode;

4) branches of various lengths can be used in the thermopile, which makes it possible to more accurately coordinate parameters such as the optimal current and temperature difference for each pair of p- and n-type branches, which results in an increase in the energy efficiency of the thermopile and the whole device.

Literature

1. Anatychuk L.I. Thermocouples and thermoelectric devices. Kiev: Naukova Dumka, 1979.

Claims (1)

A device for fastening parts by the method of freezing, including thermoelectric batteries, consisting of semiconductor thermoelements connected in series to the electric circuit via connection plates, each of which is formed by two branches made of p- and n-type semiconductors, respectively, in thermal contact with the part (by freezing), and a heat release system, characterized in that the pairing of thermoelectric batteries with the part is carried out by means of a pipeline a, divided by a control unit into three coolant circuits, the first circuit being brought into thermal contact with the part, and each of the other two circuits mating with a thermoelectric battery, one of the thermoelectric batteries being designed to operate in cooling mode, and the second in mode heating, while the control unit communicates the circuits one and two or one and three into a single channel and ensures that either cooled or heated coolant flows in the channel For each of the thermoelectric batteries consists of alternating branches connected in series to the electric circuit by means of patch plates, respectively made of a p-type and n-type semiconductor, the electrical connection of the branches is carried out by means of a p-type branch-connection plate-n-type branch , where the p-type branch contacts the end surface with one of the surfaces of the patch plate, and the n-type branch contacts the other, with each branch in the thermoelectric battery contacting end faces with two connection plates, the connection plates having an area slightly larger than the cross-sectional area of the p- and n-type branches, as a result of which their ends extend beyond the surface of the structure formed by the branches of the thermoelectric battery, the ends of the connection plates making cold contacts , protrude beyond one surface of the structure, and the ends of the connecting plates making hot contacts, beyond the other, and the free ends of the connecting plates are made with HAND T-shaped and are soldered to the electrically insulated from each other pads formed as films of metals or alloys deposited on a ceramic plate.

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