JPS5939441A - Operating method of warm heading machine and preheating method of heading punch - Google Patents

Abstract

PURPOSE:To prevent the formation of a button head having an inadequate shape by preheating the tip of a heading punch up to the saturation temp. of the heading punch shown by a heading cycle time in the stage of starting the operation of a warm heading machine. CONSTITUTION:A heading punch 2 is driven prior to a heading sequence and the tip 21 of the punch 2 is inserted into the prescribed position in an induction heating coil C. The coil C is then energized to preheat the tip 21 until said part is uniformly heated up to the saturation temp. of the punch 2 substantially higher than 450 deg.C which is the formable line for the button head of a normal shape. Thereafter the punch 2 is advanced to a position L in a direction (a) and a PC steel bar W is inserted in a direction (d) up to the position L and is held by a chuck mechanism 1. The bar W is heated to a prescribed temp. by the coil C and the punch 2 is slowly advanced in the direction (a), thereby forming a button head WH to the bar W.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of operating a warm heading machine and a method of preheating a heading head.

A complex rod for Solestress concrete (hereinafter referred to as a PC steel rod) is often formed with a 1c + J-kun head at the end and used for locking during tension (see Fig. 1 for forming the above 7g tongue head). A warm heading machine is used as shown in FIG. .

The forging punch 2, which can move forward and backward in the direction of the arrow ←→b, is advanced in the direction a, and the end face of the tip 21 of the forging punch 2 is moved to the position Lf shown by the dashed-dotted line in the induction heating coil C.
:The ape steel rod W is taken and put into a standby state.The ape steel rod W is carried in from the right side of the figure according to the arrow d through the passage of the chuck mechanism 1 which is in the released state, and its end surface is brought into contact with the end surface of the tip 21 of the forging punch 2. They collide, and the end is inserted into the heating coil C as shown by the solid line, and the forward movement is stopped and positioned. Heading nokunchi 21 of the above pcfj8 rod W
The collision with the chuck mechanism 1 is detected by a detection mechanism (not shown), and the chuck mechanism 1 is closed in response to a detection signal generated by the detection mechanism and grips the PCC steel bar. Next, heading punch 2
moves back in the direction of the arrow and heats the tip 21 of the heating coil C.
After retreating to the outside as shown by the solid line, the power supply (not shown) is fully turned on and the induction heating coil C is energized for a predetermined period of time. After energization, the forging punch is slowly advanced in the Zta direction, and the PCC is heated to a predetermined humidity, for example, 400 to 450°C.
The end of the steel bar is pressed by the tip end face of the forging punch 2, and plastic working is performed while the end face of the forging punch 2 reaches the most forward position shown by the broken line, resulting in a button head W T (as shown by the broken line).
is formed. PC copper e with butane head WH formed
The chuck w is released from the chuck machine s2 and transported out.

By the way, the button head Wit is formed by pressing the end face of the rod W heated to a predetermined hot water temperature with the tip end face of the forging punch 2, so if the tip 21 is cold, the edge 2 When pressed, the temperature of the heated part of the PCC steel bar transfers to the forging punch 2 through the contact surface by heat conduction, so the end of the PCC steel bar, which has been heated to a predetermined temperature, will not experience a drop in hot water temperature. Then, for example, by applying cold heading as shown in Fig. 2 (a), it becomes a dumpling shape similar to the shape when it is made.
It is formed into an irregular shape as shown in 2nd [ir, + (b)], and not only is the shape and function unsuitable for locking during tensioning of the PCM undergarment, but also due to the work hardening phenomenon. Tongue head W
) Only I has abnormally high hardness, which causes delayed fracture during use on other days.

Therefore, when starting the operation of a conventional warm heading machine, or when the loading of PCC steel rods is temporarily interrupted and the operation is resumed after being temporarily stopped, the heading process is warmed up and the heading process is carried out. Until the Tanino Head W)I is formed into a normal shape, the number of PC steel rods with incorrectly shaped button heads formed as a test shot will be discarded, although the number will vary depending on conditions such as the air temperature and the temperature of the TIC steel rod. It could reach up to 6 trees, making it uneconomical.

The present invention has been made in order to solve the above-mentioned problems existing in conventional warm heading machines. The present invention provides a complete method of operating a warm heading machine and a method of preheating a heading machine, which do not require additional equipment such as a kamori.

The gist of the first invention of the present application is as follows: (1) At the start of operation of the heading machine, the tip of the heading punch prior to the heading sequence is preheated by using an induction heating coil for heating the end of the PC steel frame. ...Do not provide a separate heating section for preheating. (2) Adjust the temperature for preheating the tip of the forging punch to the punch indicated by the cycle time of the forging punch performed during operation. By setting the temperature to be almost the same as the saturation temperature of the button head, by setting the temperature to be above the lower limit at which a button head with a normal shape can be formed, there is also a margin in the timing of feeding the PCW 4 rods to the heading machine. The method of operating a warm heading machine is characterized by:

The gist of the second invention of the present application is as follows: (1) When the tip of the forging nokunchi is preheated to the saturation temperature at the start of operation of the warm heading machine, the tip is inserted to a predetermined position in the induction heating coil; ) The power output of the induction heating coil is set to a predetermined value, and (3) energization and discontinuation of energization are repeated multiple times over a predetermined period of time, and (4) the temperature is raised almost uniformly over the entire cross section. Preheating the 4' inch of heading of the warm heading machine,
It's in the method.

The present invention will be explained with reference to FIGS. 3 to 5.

In the present invention, when starting the continuous rotation of the warm heading machine, the heading punch 2 is driven prior to the forging sequence, and the tip 21 of the heading punch 2 is heated by induction for heating the inner part of the PCC steel bar. Insert it into the coil C up to the position shown in FIG. 3, for example. Next, the power supply E of the induction heating coil C is closed, and a current of a predetermined frequency is passed through the induction heating coil C, and the tip 21 of the forging punch 2 is heated by the magnetic flux generated from the induction heating coil C. @ By the way, the output and frequency of the induction heating coil C and its power source are set to achieve optimal heating by forming a proper button head WH on the end of a PCC steel bar by warm heading.
Moreover, as is clear from a comparison between FIG. 1 and FIG. 3, the gap between the inner diameter of the induction heating coil C and the outer periphery of the tip 21 of the forging punch 2 is PCf'i! 4-rod W end 7JI
Since the gap between the inner diameter of the heating coil 2a and the outer periphery of the PCC steel rod is smaller than the gap between the inner diameter of the heating coil 2a and the outer periphery of the PCC steel rod, it is found that it is not suitable for heating the entire tip 21.

Therefore, preheating of the prehistoric part 21 requires a heating method different from that used when heating the end of the PCC steel rod.

In order to solve the above problems, the present inventor first analyzed the temperature change at the tip of a forging punch when a conventional forging machine starts operating and forging is performed continuously at a normal cycle time. Immediately before pressing the end of the heated PC steel bar, touch the contact type temperature measuring device to the center of the end face of the tip of the forging punch d11] Repeat the temperature NJJ process from the start and measure the temperature value. The temperature characteristic curve shown in FIG. 4(a) was obtained by plotting the locusometric eζ plot with the vertical axis representing the forging of the head and the horizontal axis. The warm forging tower used was a type in which the button head was forged with metal on a 7.4 inch PC61'% bar. According to Figure 4 (a), fk: The temperature of the large forging punch rises rapidly from the start and continues to remain almost constant at around 230°C from the number of forged punches of about 20 or more. υ, the saturation temperature of heading and gunchi was confirmed. It was also confirmed that the forged button head has a normal shape when the temperature of the forging punch is 150° C. or higher.

Inventors t, t: 'Furthermore, is the forging/P punching saturated after the operation of the above-mentioned warm heading machine is stopped? The temperature decreased from 1i71 degrees due to natural cooling, and the temperature was measured using a contact temperature measuring device attached to the tip end face of the punch.
The measured temperature value is plotted on the vertical axis and the elapsed time is plotted on the horizontal axis as shown in Figure 4 (b). ), the heading punch is 60
! It was confirmed that when the temperature exceeds Iee, the normal-shaped specimen cools down to a temperature of 150° C. or lower at which a tongue head cannot be formed.

Based on the above analysis, the inventor has determined that the tip portion 21 of the forging punch 2
What is the preheating temperature for the normal shape? The saturation temperature of the forging punch 2 was set to sufficiently exceed 150° C., which is the line at which a head can be formed, so as to allow enough time for the PC steel rod W to be delivered to the warm forging machine after preheating.

Furthermore, the present inventor designed a power source for the induction heating coil C so that the forging punch 2 would not be heated above the saturation temperature and that the heating would not be limited to the outer periphery of the tip 21 of the forging punch 2. Output 1 p c Set the output unrelated to the output when heating the 14 rods, for example, 50%, and completely power the tip 21 of the forging d'inch 2 by the energization cycle as shown in the time chart in Fig. 5. It was configured to preheat to a substantially uniform saturation temperature over the cross section. In Fig. 5, th indicates the energization time, and ts indicates the energization stop time.By repeating the energization and energization stop several times, the induction heating coil C generates a large magnetic flux, which causes a large amount of induction heat generation. The heat from the surface layer is conducted to the center, raising the temperature uniformly across the entire cross section. Energization time t
h, the energization stop time ts, and the number of repetitions are determined based on various conditions such as the power output, the frequency, the diameter of the forging punch to be used, and the size of insertion into the induction heating coil C.

Through the above operations, the tip 21 of the forging punch 2 is preheated to the saturation temperature, and then moves forward in the direction of the arrow a in the induction heating coil C, which is no longer energized, until it reaches the position shown by the dashed-dotted line in FIG. The machine then stops and waits for the positioning of the PCjijil rod W that is brought in according to the forging sequence that is about to start. In this way, the warm heading machine forges normal-shaped button heads wHft from the first forged product, and all normal-shaped button heads WH are forged according to the continuous forging cycle time, and the operation continues.

By implementing the present invention, (1) At the start of operation of the B heading machine, the end el of the PC steel bar! Since the heating source for cold heading is used to preheat the heading/gunchi, the heat source setting (I7
(2) Since the preheating edge heat source is induction heating, the preheating temperature can be controlled more reliably compared to, for example, a combustion gas flame, and (3) the preheating temperature can be completely pressed or Since the temperature is set at the saturation temperature of m degrees, there is plenty of time from the end of preheating to the time when the PC steel bar is brought in for heading, and it is possible to produce a certain quality of forging. (4) Completely eliminate the waste of trial driving The effect is extremely large.

[Brief explanation of the drawing]

Figure 1 is a partially sectional front view showing the main parts of the warm heading machine;
Figures (a) and (b) are front views of an irregularly shaped button head forged on the end of a PC steel bar, respectively, to explain the problems that exist when a warm heading machine starts operation, and Figure 3 is a non-inventive button head. A partial cross-sectional front view of the main parts of the warm heading machine, vg4 diagrams (&) and (b) explain the operating method of the warm heading machine, respectively.
FIG. 5 is a temperature characteristic curve diagram that analyzes the temperature rise due to the start of operation of the punch and the temperature decrease after the operation is stopped, and FIG. 5 is a time chart illustrating the method for preheating the forging punch of the present invention. 1...Chuck mechanism 2...Forging punch 21...Forging punch tip C...Induction heating coil W...PC steel bar W H...Button head E...Fat tom heating coil Power supply jh... Energization time ts... Energization stop time Special clause JJJ Application Koshuha Netoren Co., Ltd. Agent Patent Attorney Fu Kobayashi Figure 1 Figure 2 (G) Figure 2 (b
) Figure 3 Figure 4 (0) Headed book bU 00 fr

Claims (1)

[Claims] 1) Equipped with a chuck mechanism, an induction heating coil, and a forging punch, the end of the PC steel undershirt gripped by the chuck mechanism is heated to a predetermined temperature by the induction heating coil, and then pressed with a forging punch of 4 inches. And to the end concerned? In a warm heading machine that forms a tongue head, at the start of operation, the tip of the forging punch is heated to approximately the same temperature as the saturation temperature of the forging A4 inch indicated by the continuous forging cycle time using the induction heating coil. A method for operating a warm heading machine, characterized in that a heading sequence is executed after preheating. 2) At the start of operation of the warm heading machine, which heats the end of the PC steel bar gripped by the chuck mechanism to a predetermined temperature with an induction heating coil and presses it with a forging punch to form a butane head on the end, the above-mentioned When using an induction heating coil tube and preheating the tip of the forging punch to a temperature that is approximately the same as the saturation temperature of the forging punch indicated by the continuous forging cycle time, Insert the tip of the punch to a predetermined position inside the heating coil, set the power output of the induction 7JII heating coil as predetermined, and turn on and off the current for a predetermined time several times. A method for preheating a warm heading machine, characterized in that the temperature is raised almost uniformly over a period of time.