JPH03283511A - Transformer for welder - Google Patents

Abstract

PURPOSE:To get over a skin effect caused at a high frequency for making a reduced-size and light-weight transformer by making a plurality of grooves on the surface of a secondary coil and by providing a cooling water path through the secondary coil to cool it down. CONSTITUTION:With high-frequency ac power input into a primary coil 10, a same-frequency ac electromotive force is induced between both ends 16 and 18 of a secondary coil 12. the ac electromotive force is converted by rectifying devices 24, 24 into dc to be output from between center-tap terminal strips 24 and 20. At this time, a high-frequency large current flows in the secondary coil 12, resulting in generation of heat and skin effect which would increase an energy loss. However, heat generation is controlled by cooling water which is running in a cooling water path 28. The cooling water path 28 through the secondary coil 12 and the grooves 30 on the surface of the secondary coil 12 remarkably increase a surface area of the secondary coil 12, with a result of a sharp reduction of energy loss which would be caused by a skin effect.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high-frequency welding transformer used in an inverter type resistance welding machine and the like.

[Prior Art] As is well known, welding robots equipped with resistance welding machines are generally used in automobile welding lines, etc., and alternating current power is stepped down through a welding transformer of the resistance welding machine and is made to have a large current. Later, this is supplied to the object to be welded via the welding gun arm.

This type of resistance welding machine supplies a large current from the welding transformer to the welding gun arm, so the welding transformer is generally large and tends to be heavy. In order to increase speed, it is desirable to make it smaller and lighter.

In this type of welding transformer, by performing its input and output at high frequencies, the required cross-sectional area of the core can be reduced, and as a result, the welding transformer can be made smaller and lighter. As the resistance welding machine, a so-called inverter type resistance welding machine is often used, which first converts the AC power into DC power, then converts it to high frequency AC using a switching circuit, etc., and inputs this into a welding transformer. ing.

However, when inputting and outputting to a welding transformer is performed at high frequencies in this way, although the core can be made smaller and lighter, the outer skin of the secondary coil and secondary coil is The effect is increased energy losses, which are particularly noticeable in secondary coils where large currents flow.

For this reason, both coils of such a welding transformer, especially the secondary coil, have a very small surface area in order to reduce the energy loss due to the skin effect. This has been an obstacle to further miniaturization and weight reduction of the secondary coil, and further miniaturization and weight reduction of the welding transformer.

[Problems to be Solved by the Invention] The present invention has been made in connection with such technology, and it is an object of the present invention to provide a welding transformer that can be further reduced in size and weight by overcoming the skin effect of high frequencies. With the goal.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a high-frequency welding transformer used in a welding machine, in which a plurality of grooves extending in the longitudinal direction of the secondary coil are provided on the surface of the secondary coil. It is characterized by

The present invention is characterized in that a cooling water passage is provided through the secondary coil through which cooling water flows to cool the secondary coil.

Furthermore, it is characterized in that the groove portion is provided on an outer surface of the secondary coil or an inner surface forming the cooling water passage.

Alternatively, the groove portion is provided on an outer surface of the secondary coil and an inner surface forming the cooling water passage.

[Function] By providing a plurality of grooves extending in the longitudinal direction on the surface of the secondary coil, the surface area increases, and therefore, the cross-sectional area of the secondary coil can be made relatively small.

By providing the cooling water passage through the secondary coil, the inner surface of the secondary coil forming the cooling water passage also contributes to an increase in the surface area of the secondary coil.

In this case, the surface area of the secondary coil can be increased by providing the groove on either the outer surface of the secondary coil or the inner surface forming the cooling water passage. Note that when the grooves are formed on the inner surface, the cooling effect can be further enhanced.

Further, by providing the groove portion on both the outer surface of the secondary coil and the inner surface forming the cooling water passage, the surface area of the secondary coil can be further increased.

[Example] Next, an example of a welding transformer according to the present invention will be described in detail below with reference to the accompanying drawings.

1 and 2 are a schematic side view and a schematic plan view showing an example of the welding transformer, respectively, FIG. 3 is a perspective view of the secondary coil of the welding transformer, and FIGS. FIG. 3 is a cross-sectional view of the coil.

In FIG. 1 and FIG. 2, reference numeral 1O is a single layer coil, 12 is a secondary coil, the secondary coil 10 has a number of turns of many turns, and the secondary coil 12 has a number of turns of 2 turns, for example. A center tap terminal plate 14 is led out from the neutral point of the secondary coil 12, as shown in FIG.

In this case, although not shown in FIG. 3, the secondary coil 12 has a cross-sectional shape as shown in FIG. 4 a, b, or c.

Secondary coil 100 winding start end 16 and winding end end 18
are opposed to each other with an interval as shown in Fig. 3,
A terminal plate 20 is interposed between these, and the terminal plate 20 is connected to both ends 1 of the secondary coil 12 by a plurality of insulating bolts 22.
It is fixed at 6.18.

On both sides of this terminal plate 20, a pair of rectifying elements 24, 24 formed in a disk shape are provided as shown in FIGS. 1 and 2.
are integrally fixed.

In this case, both rectifying elements 24,24 are electrically connected to the winding start end 16 and the winding end end 18 of the secondary coil 12 through the electrode cases 26 forming the outer surface thereof, respectively. The winding start end 1 can be energized only from the winding start end 16 and the winding end end 18 toward the terminal plate 20.
6 and the end portion 18 of the winding are connected to the terminal plate 20.

Inside the secondary coil 12, as shown by the broken line in FIG. 3 and in FIG.
A cooling water passage 28 extending in the longitudinal direction over almost the entire length is provided through the secondary coil 12 at both ends 16.1 of the secondary coil 12.
The secondary coil 12 is cooled by flowing cooling water through the cooling water passage 28 from one side of the coil 8 to the other.

Further, the outer surface of the secondary coil 12 and the inner surface forming the cooling water passage 28 are provided with, for example, as shown in FIG. 4a.
A plurality of grooves 30 are provided at intervals in the circumferential direction of the secondary coil 12, extending in the longitudinal direction over almost the entire length from the winding start end 16 to the winding end end 18.

In FIG. 3, reference numerals 32 and 34 indicate cooling water passages formed in the center tap terminal plate 14 and the terminal plate 20 to cool them, respectively.

Next, the operation of the welding transformer having such a configuration will be explained.

In this welding transformer, when high frequency AC power is manually applied to the secondary coil 10, both ends 16.1 of the secondary coil 12
An alternating current electromotive force of the same frequency is induced between the center tap terminal plates 14 and 20, and this alternating electromotive force is converted into direct current by the rectifying elements 24 and 24 and output from between the center tap terminal plate 14 and the terminal plate 20.

At this time, since a large high-frequency current flows through the secondary coil 12, heat generation and a skin effect occur, which tends to increase energy loss. However, the heat generation is suppressed by the cooling water flowing into the cooling water passage 28.

On the other hand, regarding the skin effect, by providing the cooling water passage 28 through the secondary coil 12, the surface area of the secondary coil 12 including the wall surface of the cooling water passage 28 is increased.
By forming the grooves 30 on the outer and inner surfaces of the secondary coil 12, the surface area of the secondary coil 12 is greatly increased, and therefore energy loss due to the skin effect is significantly reduced.

In this way, in this welding transformer, the secondary coil 120
By forming the grooves 30 on the surface and greatly increasing its surface area, even if the secondary coil 12 is downsized and its cross-sectional area is reduced, it is still sufficient to reduce energy loss due to the skin effect. The surface area can be secured, and therefore the welding transformer can be made smaller and lighter.

In this embodiment, the grooves 30 are formed on both the outer and inner surfaces of the secondary coil 12, but depending on the degree of skin effect, the grooves 30 may be formed on the secondary coil 12 as shown in FIGS. Even if the groove portion 30 is formed only on either the outer surface or the inner surface as in this embodiment, it is possible to secure a sufficient surface area to reduce energy loss due to the skin effect. Even in the case of the secondary coil 12
Therefore, it is possible to reduce the size of the welding transformer.

[Effects of the Invention] As is clear from the above description, according to the welding transformer of the present invention, by providing a plurality of grooves extending in the longitudinal direction on the surface of the secondary coil to increase the surface area, high frequency It is possible to reduce the cross-sectional area of the secondary transformer while reducing energy loss due to the skin effect in the welding transformer, thereby making it possible to reduce the size and weight of the welding transformer.

By providing the cooling water passage through the secondary coil, it is possible to suppress the heat generation of the secondary coil, and the inner surface of the secondary coil forming the cooling water passage also The surface area can be further increased, the secondary coil can be further downsized, and the welding transformer can be made smaller and lighter.

In this case, the grooves can be provided on both the outer and inner surfaces of the secondary coil, and in particular, when the grooves are provided on both sides, the surface area of the secondary coil can be significantly increased, and the It is possible to further reduce the size and weight of the welding transformer. Furthermore, providing a groove on the inner surface of the secondary coil has the advantage that the cooling effect is further improved.

Furthermore, by making the welding transformer smaller and lighter in this way, the operating speed of the welding robot to which it is attached can be increased, thus improving the cycle time of the welding line in which the welding robot is installed. can.

[Brief explanation of the drawing]

1 and 2 are a schematic side view and a schematic plan view showing an example of the welding transformer of the present invention, respectively, FIG. 3 is a perspective view of the secondary coil of the welding transformer, and FIGS. FIG. 3 is a cross-sectional view of the secondary coil. lO... - Secondary coil 12... Secondary coil 14... Center tap terminal plate 16... Winding start end 18... Winding end end 20... Terminal plate 28... Cooling water Passage 30...Groove 32.34...Cooling water passage

Claims (4)

[Claims] (1) A high-frequency welding transformer used in a welding machine, characterized in that a plurality of grooves extending in the longitudinal direction of the secondary coil are provided on the surface of the secondary coil. (2) The welding transformer according to claim 1, wherein a cooling water passage is provided through the secondary coil through which cooling water flows to cool the secondary coil. (3) The welding transformer according to claim 2, wherein the groove portion is provided on the outer surface of the secondary coil or on the inner surface forming the cooling water passage. (4) The welding transformer according to claim 2, wherein the groove portion is provided on an outer surface of the secondary coil and an inner surface forming the cooling water passage.