JPS6027401A - Manufacture of shaped steel bar with screwed knar - Google Patents

Abstract

PURPOSE:To prevent the torsional phenomenon of a steel bar by providing a pair of flat rolls for nipping the width part of the bar to the outlet side of screw finishing rolls and giving an inverse torsional force for correcting the torsion of the bar delivered from the finishing rolls in manufacturing a reinforcing steel bar with screwed knar. CONSTITUTION:A reinforcing steel bar 3 with screwed knar is delivered from screw finishing rolls 1, after being somewhat twisted depending on the shape of a screwed knar at the time of roll forming the screwed knar. A pair of flat rolls 2 for nipping the flat part of the bar 3 is arranged just behind the outlet of the rolls 1, and the torsional phenomenon is corrected by providing an inverse twisting angle required for correcting the torsion to the roll 2 shafts through a flat roll holder 6 by rotating a worm 7 for rocking. Further, the application of a light rolling reduction to the flat part of the bar 3 by decreasing the roll gap between a pair of flat rolls by a rolling reduction worm 9, is also available instead of said correction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for manufacturing a deformed steel bar with threaded joints (hereinafter referred to as threaded reinforced steel bar).

(Prior art) Threaded reinforced steel bars are not affected by the weather during construction and are advantageous in terms of construction time. They are used in a wide range of applications where only mechanical joints are permitted, and there are no steps in the joints. It has been widely used in recent years because it is suitable for cases where sticking causes problems. Its shape is shown in Figure 1 (a) (b) I
As shown in C, a spiral knot is formed on the surface of the steel bar during rolling by a finishing roll with a thread-shaped caliber carved into it. At this time, a component of the force in the rolling direction acts in the direction of the helical knots, thereby generating a rotational moment in a certain direction in the steel bar and causing twisting.

There is no problem with screw reinforcing steel bars that are twisted in this way when they are used as straight bars, but problems arise when they are bent. In other words, when bent into an arc shape, the section modulus Q,
Since bending deformation occurs in the smaller direction, the threaded reinforcing steel bar bends along the twisted width part, and the threaded reinforcing steel bar does not bend uniformly after processing. As a result, the joints of the threaded reinforced steel bars become misaligned, making it impossible to connect them.

As a method for solving the problem of screw reinforcing bar needle 1, Japanese Patent Application Laid-open No. 8?158-16705 (Japanese Patent Application No. 1983
5.819). The method is to inscribe the grooves on the finishing roll by tilting them, and the torsional force in the opposite direction to the torsional force of the steel bar is applied due to the differential moment of circumferential speed that occurs between the upper roll groove and the lower roll groove. Therefore, the torsion angle of the product is the same as the lead angle of the threaded reinforced steel bar, so the inclination angle of the hole carved on the finishing roll should also be the same as the lead angle of the threaded reinforced steel bar. There is a description.

However, the present inventors investigated the relationship between the lead angle and the amount of twist of the steel bars for seven types of copper screw reinforcing bars with different lead angles, and found that although the amount of twist is roughly proportional to the lead angle, as shown in Figure 2, However, it was found that the amount of twist in the steel bar varies.

(Object of the Invention) The present invention has been constructed in view of the above facts, and its purpose is to provide a ζ-roar, a threaded knurled variant that can prevent twisting of a steel bar that occurs when forming spiral knots with a finishing roll. To provide a method for manufacturing steel bars.

(Structure and operation of the invention) The gist of the present invention is that in a method for manufacturing a deformed steel bar with threaded joints in which spiral knots are formed on the surface of the steel bar in a hot finishing mill, the roller gap is defined as the width dimension of the steel bar. 11? If a flat roller with the same settings as ``I'' is placed at the exit of the finishing roll and clamps the width part of the steel bar at an appropriate inclination angle according to the twist of the steel bar, it will be able to resist the twisting force of the deformed steel bar. A method for manufacturing a threaded deformed steel bar characterized by applying a twisting force in the opposite direction.

The present invention will be explained in detail below.

FIG. 3 is an explanatory diagram for showing one embodiment of the present invention,
Finishing roll 1 and a flap provided on its exit side.

The troller 2 is shown in a plan view. The threaded reinforcing steel bar 3 is rolled by the finishing roll 1, and at the same time spiral knots are formed on the surface, which progresses to the right in the figure. A clockwise twisting moment acts on the steel bar 3 from the finishing roll 1 toward the flat roller 2. Therefore, the flat roller 2 clamps the width part of the threaded reinforcing steel bar 3 and tilts it in the opposite direction of the twist as shown in FIG. 4, which is the view from arrow A-A in FIG. This is to prevent twisting by adding a moment to prevent twisting.

In the case of this embodiment, the pace 4 of the flat roller 2 is fixed to the finishing stand nokuruken 5 with a bolt or the like, and is tiltably connected to the roller hole 7 by a swinging worm 7 and a swinging worm wheel 8. ing. Since the flat row 2 holder 6 swings around the threaded reinforced steel bar 3 by rotating the swinging worm 7 and the worm wheel 8, the inclination angle of the flat roller 2 installed therein can be freely changed.

In addition, as shown in FIG. 4, in this embodiment, the axis of the flat roller 2 and the axis of the rolling-down worm wheel 1o are made eccentric, and the rolling-down worm 9 is rotated to shift the shaft.
By changing the interval between the two, the amount of reduction can be adjusted.

Note that both the worm 9 for rolling down and the worm wheel lo for rolling down have reverse threads on the left and right sides.

We will discuss the results of preventing twisting of threaded reinforcing steel bars using the above method. C: 0.23%, Mn: 1.50%,
A D32 threaded reinforced steel bar with a lead angle of 9.1 degrees was manufactured from a billet of 162 containing St: 0.35%. At this time, the distance between the finishing roll and the 7th roller is 5
The length was 50m, but the inclination angle of the flat roller was 3d@
At G, no twisting occurred at all.

In addition, the present invention is characterized in that the width portion of the threaded reinforcing steel bar is simultaneously lightly rolled down by the troller, and its purpose is to produce a threaded reinforcing steel bar with the same width within the billet, between the billet and the billet. There is a particular thing. When bending with a curvature of 25 mH is being performed using an inder with a distance between fixed rollers of 600 mH, the curvature changes to 20 mH if the dimension of the threaded reinforcing steel bar perpendicular to the bending surface increases by 0.5. The curvature must be constant during construction, so items with different curvatures must be reworked, and if the curvature of each threaded reinforcing bar is different, the construction will have to be stopped.

The present invention focuses on such a problem, and as mentioned above, when deformed during bending, the width part of the threaded reinforcing steel bar becomes a curvature surface due to the section modulus, so it is important to keep the width dimension constant.

(Effects of the Invention) As explained above, the present invention not only prevents twisting of threaded reinforced steel bars during rolling, but also enables production of threaded reinforced steel bars with constant width dimensions and prevents trouble during construction. It is extremely useful as a countermeasure.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the shape of a threaded reinforced steel bar, Figure 2 is a diagram showing the investigation results of the relationship between the lead angle and twist amount of the threaded reinforced steel bar, and Figure 3 is a diagram showing one implementation of the present invention. Explanatory diagram, 4th
FIG. 3 is a view taken along the line A-A in FIG. 3; 1... Finishing roll, 2... Flat roller, 3...
・Screw reinforced steel bar, 4...Pace, 5...Palken,
6... Flat roller holder, 7... Worm for swinging, 8... Worm wheel for swinging, 9... Worm for rolling down, 10... Worm wheel for rolling down Figure 1 (α) (b) Figure 2 Word fl (tkgl Figure 3 Figure 4

Claims (2)

[Claims] (1) In a method for manufacturing threaded deformed steel bars in which spiral knots are formed on the surface of the steel bar using a hot finishing mill, a flat roller with the roller gap set to the same width as the steel bar #1 is used at the exit of the finishing roll. It is characterized by applying a twisting force in the opposite direction to the twisting force of the threaded deformed steel bar by sandwiching the width part of the steel bar at an appropriate inclination angle according to the twist of the bar hook. A method for manufacturing a deformed steel bar with threaded joints. (2) The method for producing a threaded deformed steel bar according to claim 1, characterized in that the width portion of the threaded deformed steel bar is simultaneously lightly rolled down by a flat roller.