JPS6012142B2 - Induction heating elbow joint processing equipment - Google Patents

Description

[Detailed description of the invention] The present invention relates to an induction heating type elbow joint processing device.

Conventional elbow joint processing equipment of this type attaches a mandrel as a shaping section whose diameter gradually increases and curves to the tip of a workpiece guide rod, inserts the workpiece from the end of the workpiece guide rod, and presses the workpiece. The workpiece is sequentially sent to the shaping section, and in the furnace surrounding the shaping section, the workpiece is heated with a burner to expand and shape the elbow joint. ``This method is usually called the mandrel bending method of a combustion furnace. This conventional elbow joint processing equipment has problems such as bulges (due to flattening), cracks, wrinkles, and poor shape in the center of the elbow joint, especially when manufacturing large-diameter elbow joints with pipe diameters exceeding 10 inches. was occurring.

However, in order to solve the above problem, we conducted various experiments and discovered that the above problem was solved by heating the workpiece at a uniform temperature from the beginning to the end of the process and extruding it with a constant press pressure. The cause was clarified.

In other words, it has been found that it is better to mold the workpiece by changing its temperature during the steps of expanding and bending the workpiece. As a result of the above-mentioned research, the present invention provides an elbow joint processing device that can produce products without bulges (deformation), cracks, defects (uneven heating), etc. in the center of the elbow joint.

That is, in the present invention, the guiding heating device is divided into three parts: a child heating coil, an expanding heating coil, and a curved heating coil, and the child heating coil is arranged at the tip of the work guide rod adjacent to the mandrel. Three positions are selected and arranged: the outer periphery of the expanding part of the mandrel, the expanding heating coil on the outer periphery of the expanding part of the mandrel, and the curved heating coil on the outer periphery of the curved part of the mandrel, and electric power is adjusted to each of the heating coils. This is a conductive heating type elbow joint processing device characterized in that it is supplied with

An embodiment of the present invention will be described below with reference to the drawings.

In this figure, a mandrel 2 whose diameter gradually increases and curves downward is attached to the tip of a work guide rod 1.

A preheating coil 3, a broadside heating coil 4, and a curved heating coil 5 are divided into three parts on the outer periphery of the part la of the work guide rod 1 near the expanded part 2a of the mandrel 2, the expanded part 2a, and the curved part 2b, respectively. placed and properly supported. Between the preheating coil 3 and the work guide rod 1, the expansion heating coil 4
The workpiece W is placed between the work guide rod 1, the widened part 2a of the mandrel 2, and the curved part 2 of the mandrel 2, and between the curved heating coil 5 and the curved part 2b of the mandrel 2, respectively.
At b, there is an annular gap S that can move concentrically in the longitudinal direction of the work guide rod 1 and the mandrel 2. The tip of the mandrel 2 protrudes from the curved heating coil 5 to form a shaping portion 2c. Then, the preheating coil 3 and the expansion heating coil 4
, a high frequency current is passed through the curved heating coil 5, and the workpiece W is sequentially pressed into the preheating coil 3, the expansion heating coil 4,
It is sent to a heating section consisting of a curved heating coil 5. Numerals 6, 7, and 8 are power sources for supplying high-frequency current, and the heating temperature can be adjusted separately.

The high frequency power supply 6 is a power switch SS connected to a commercial power supply.
, a transformer section 6a consisting of a transformer T; a forward converter B, and a forward converter C. , a DC reactor R, and an inverse conversion section 1; a high frequency conversion section 6b consisting of a transformer T; a matching section 6c consisting of a power factor adjustment capacitor C, a changeover switch CS, and a matching transformer T2. The high frequency power supplies 7 and 8 also have a similar configuration. The heating temperature applied to the workpiece W for shaping is made such that the heating areas of the preheating coil 3 and the curved heating coil 5 are approximately equal;
The area of the expanded heating coil 4 is raised. In this way, the heating temperature can be adjusted for each coil by "Work W".
This is to mold the material smoothly and efficiently. For example, if the temperature given by all the coils is made equal to that of the highest expansion heating coil 4, the workpiece W entering the heating area of the preheating coil 3 will be suddenly heated to a high temperature, becoming soft in the middle and moving outward in the radial direction. Since it expands and is pushed in all directions, it collapses into a flattened state, which is undesirable. After all the workpieces W inserted into the workpiece guide rod 1 are formed and taken out from the mandrel 2, a predetermined number of new workpieces W are inserted into the workpiece guide rod 1 again.

During this time, the Matsukai heating coil 4 and the curved heating coil 5 are maintained in a heat-retaining state such that the temperature of the latter is higher than that of the former. However, this insulating temperature is set to be considerably lower than the above-mentioned heating temperature. As a result, the workpiece W can be smoothly heated and formed when the next heating cycle starts, and the mandrel 2 will not be destroyed by thermal stress. In this way, the workpiece W heated by the preheating coil 3 is heated by the expansion heating coil 4.
It is widened by the gunwale 2a of the mandrel 2 in the region , further curved in the region of the curved heating coil 5, and shaped by the shaping portion 2c to form an elbow joint and extruded downward.

As is clear from the above, "According to the present invention, the heating of the workpiece is performed using a preheating coil formed by dividing the heating coil into three parts.
Expanded heating coils and curved heating coils are arranged around the outer circumference of the mandrel, and each heating coil is processed at different temperatures in stages using a separate high-frequency power source, so it is especially suitable for pipes with a diameter of 10 inches or more. When manufacturing large-diameter elbow joints, you can obtain elbow joints that are free from uneven heating, undesired deformation, and cracks.

In addition, since the device of this invention is an induction heating type, there is no generation of SO x 10 m and NO x 120 m in the working atmosphere, and the combustion noise is reduced to 90 h, compared to 113 h of the burner. did.

Furthermore, the large amount of heat radiated from the furnace that workers were previously exposed to is almost eliminated, and production efficiency has been reduced from the previous average of 3 to 3.
It increased five times. In addition, as the forming speed increases, the workpiece is not heated in the furnace for a long time, which extends the service life of the mandrel tool and prevents oxidation scale from burning. Yield is improved because there is little loss, and there are fewer burnt skins and molding scratches, reducing the rate of corrections.

[Brief explanation of drawings]

The drawing is a partial vertical sectional view of the induction heating type elbow joint processing apparatus of the present invention. 1...

Claims (1)

[Claims] 1 A mandrel 2 whose diameter gradually increases and is curved is connected to the tip of a work guide rod 1 that guides a cylindrical work W, and a preheating coil 3 is installed around the outer periphery of a portion of the work guide rod 1 near the mandrel 2. , an expanded heating coil 4 is provided on the outer periphery of the expanded portion 2a of the mandrel 2, and a mandrel curved portion 2b.
A curved heating coil 5 is disposed on the outer periphery of the workpiece W, and the workpiece W is disposed between the workpiece guide rod 1 and the preheating coil 3, between the mandrel 2, the expansion heating coil 4, and the curved heating coil 5. An induction heating type elbow joint processing apparatus characterized in that an annular gap S through which the workpiece W can pass is provided, and electric power for heating the workpiece W to an appropriate temperature is supplied to each of the coils 3, 4, and 5 in an adjustable manner.