JPH0364217B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing screws using an inclined rolling mill, and specifically, square screws used in screw feeders etc. by a plastic working method using an inclined rolling mill. The present invention also relates to a method of manufacturing screws such as rods with spiral fins.

[Prior art]

The screw feeder uses a rod with spiral fins (hereinafter referred to as the screw shaft) in which the fin part and the fin bottom base material are integrated. A method of cutting out by machining is used. However, in this case, there are problems in that the material yield is low and the machining cost is extremely high because it is difficult to increase the machining speed in machining the screw shape.

As a method other than this, application of a thread rolling method can be considered. This thread rolling method is a method in which threads provided on the surface of a rolling die are transferred to the surface of a cylindrical body of a raw material.

However, when using this method, the pitch is short,
In addition, only so-called screw-shaped fins can be processed in which the peaks and valleys of the fins are arranged alternately, such as a screw feeder that has a flat groove bottom between the fins, a long fin pitch, and tall, thick fins. It was impossible to apply this method to manufacturing.

Further, as a second method, there is a rolling method used for manufacturing heat exchanger tubes such as heat exchangers. This rolling method is the 9th rolling method.
As shown in the figure, three rolling rolls 31, 32, 3 are arranged around the pass line of a hollow metal tube 34.
3, the metal tube 34 is cold (or hot) rolled. The shapes of the rolling rolls 31, 32, and 33 are all the same, and for example, as shown in FIG. 10 (cross-sectional view taken along the line X-X in FIG. 9), they are shaped like a thin disc and have a thin disk shape around one shaft. A number of rolls with a wedge-shaped cross-sectional shape are arranged on the same axis.
10 pieces were installed.

In the case of the above method using such rolling rolls 31, 32, 33, as shown in FIG. 11, approximately U-shaped grooves 35a, 35b, etc. are formed on the outer surface of the hollow metal tube 34 (see FIG. 11) in the thickness direction. The grooves 35a, 35b, etc. are then rolled down with a rolling force of (see Fig. 11), and then the grooves 35a, 35b, etc. are rolled down with a disk-shaped roll, and the force acting in the direction perpendicular to the groove surface (in the direction of the arrow) at that time is applied. The depth of the fins is increased by increasing the depth of the grooves {see Figure 11}, and the amount of metal displaced by this groove processing is transferred to the gap between the disc-shaped rolls of the rolling rolls. 35
is formed. During this time, there is almost no stretching in the longitudinal direction of the tube axis, and since it is pushed away by the disc-shaped rolls, the tube with spiral fins has wide fin spacing ( (hereinafter referred to as finned tube)
A finned tube that cannot be manufactured using this method is, for example, one with a fin groove bottom diameter of 28 mmφ, a fin height of 8.5 mm, a fin thickness of 0.5 mm, and a short fin spacing of about 3.5 mm. Also, regarding the height and thickness of the fins, for example, only when the material is soft metal such as copper or aluminum, the height and thickness of the fins should be 15 mm and 0.2 to 0.2 mm, respectively.
There is a relationship in which the higher the fin height (approximately 0.5 mm), the thinner the thickness, and as in the case of thread rolling described above, there were many restrictions on product dimensions.

There is a third method proposed by the present inventors as a method that can solve the problems associated with these rolling methods and dramatically expand the range of dimensions that can be manufactured. No. 124203). In this third method, a plurality of annular grooves are cut on the outer circumferential surface of the rolling part of the inclined rolling roll so that the intervals gradually become wider from the material input side to the material output side. This method produces a finned tube with high fins and long fin spacing by hot elongating a hollow metal tube with a regulating tool inserted inside. More specifically, Fig. 12 and Fig. 13 (Fig. 1
As shown in the cross-sectional view taken along line X-X in Figure 2),
Three rolling rolls 41, 4 in which a plurality of grooves forming fins 45 are cut in the circumferential direction of the outer circumferential surface of the rolling part at intervals that gradually become wider from the input side to the output side.
An internal surface regulating tool, in the example shown, a mandrel bar 46, was inserted into the inside using a cross-type inclined rolling mill (a model with four rolling rolls may be used) in which rolls 2 and 43 were arranged facing around the pass line. In this method, a hollow metal tube 44 is hot stretched and rolled to produce a metal tube with spiral fins having a fin bottom parallel to the inner surface of the tube. In this method, since the metal tube can be hot-rolled at a high rolling reduction rate using a cross-type inclined rolling mill, elongation rolling is performed using this, and each part of the rolling part of the rolling rolls is By cutting grooves at these positions, the rolling rolls apply a rolling reduction (indicated by arrows) that increases sequentially as shown in Fig. 14, thereby increasing the fin spacing. While spreading, form a spiral fin with desired fin height and thickness.

[Problem that the invention seeks to solve]

By the way, when attempting to manufacture a finned rod by processing a solid circular cross-section metal material using the second method, the inner surface regulating tool cannot be used, so the material's axial center may be oriented in the axial direction. As a result, the material tends to sink in the radial direction, making it impossible to form high fins.

In addition, when applying the third method and trying to manufacture a finned rod from a solid material without an inner surface regulating tool, the axial center of the material is stretched in the axial direction, so the metal material is The strain component in the radial direction toward the axis of the roll increases, and the outer diameter of the fins formed in the roll grooves gradually becomes smaller as the rolling progresses (→→→), as shown in FIG. did not fill the roll groove, and as a result, the height and thickness of the fin portion of the manufactured finned rod were sometimes shorter than the target values.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method for manufacturing a screw that allows the height and thickness of the fin portion to be manufactured to target values.

[Means for solving problems]

A method for manufacturing a screw according to a first invention is a method for manufacturing a screw from a solid circular cross-section metal material by inclined rolling, wherein the outer diameter of the solid circular cross-section metal material is the same as the outer diameter of the screw. Or select a size larger than this, and roll around the pass line a plurality of conical rolling rolls formed in the circumferential direction of the outer circumferential surface at intervals where the annular grooves that form the spiral protrusions gradually widen from the input side to the output side. The method is characterized in that the circular cross-section metal material is hot elongated using three to four cross-type inclined rolling mills arranged at equal intervals.

A method for manufacturing a screw according to a second invention is a method for manufacturing a screw from a solid metal material with a circular cross section, in which an annular groove forming a spiral protrusion is formed at intervals that gradually widen from the input side to the output side. A cross-shaped slope in which three or four rolling rolls are formed in plurality in the circumferential direction of the outer peripheral surface of the rolling part, and each groove width is narrower from the entry side to the exit side, facing around the pass line. The method is characterized in that the circular cross-section metal material is hot elongated using a rolling mill.

The method for manufacturing a screw according to a third aspect of the invention is characterized in that the outer diameter of the solid circular cross-section metal material is larger than the outer diameter of the screw.

[Effect]

In the method of the present invention, it is possible to freely set the height, thickness, and pitch of the helical protrusion.

Example 1 The present invention will be specifically explained below based on the drawings.
Fig. 1 is a front view showing the implementation state of the present invention (grooves are omitted), Fig. 2 is a partially enlarged side view taken along the - line in Fig. 1, and 4 in the figure is a circular cross-section. The actual metal material, 5, indicates a rod with spiral fins, which is the product.

The metal material 4 is transferred in the axial direction and rolled by a set of three cone-shaped rolling rolls 1, 2, and 3 in a cross-type inclined rolling mill.

Rolls 1, 2, and 3 each have the same conical half angle α
{see FIG. 2}, and its axis line is inclined so that the shaft ends on the same side face the same side in the circumferential direction (the angle β of this axis line with respect to the path line is called the inclination angle), Also, the shaft end on the same side is inclined so that it approaches or moves away from the pass line (the angle γ of this axis center line with respect to the pass line is called the intersection angle, and the roll axis is on the exit side with respect to the pass line). The direction of separation is γ (defined as positive).

The opening side is wider at the portion where the distance between the outer peripheral surface of the rolling rolls 1, 2, and 3 and the pass line is smaller than the radius of the outer periphery of the metal material 4 passing therethrough, that is, the outer periphery of the rolling portion. A plurality of annular grooves, for example, 5 to 7 annular grooves each having a trapezoidal cross section, are cut in the circumferential direction at appropriate length intervals in the axial direction. The positions, intervals, widths, and depths of the grooves differ among the rolls, as partially shown in FIG. 2, and the intervals among the rolls also vary in the axial direction.

The position and spacing of the grooves are determined according to the height and spacing of the fins to be formed, and the conical half angle α, inclination angle β, and crossing angle γ of the inclined rolling roll are related to these.
etc. are determined. The positions of the grooves are different for each roll, and the pitches are gradually widened from the material input side to the material output side for each roll depending on the amount of stretching, as will be explained later. The fins coming out of one roll are guided into the grooves of the next roll and are successively shaped. The groove width and groove depth are substantially the same between the rolling rolls.
Note that the groove depth in each roll is appropriately changed from the entry side to the exit side so as to obtain a desired fin height at the exit end.

On the other hand, regarding the groove width, the more it goes from the entry side to the exit side,
The groove width at the exit side is made to match the target fin thickness. However, as shown in Figure 2, the groove width _t1 at the entrance end is approximately 1.5 times the target fin thickness t to be manufactured.
Preferably, 1.2t<t ₁ <2.5t.

Note that t ₁ and t here mean the average value of the groove width and the thickness of the fin portion coming out of the roll at the bottom and top, respectively.

In addition, when the fins to be formed are perpendicular to the surface of the metal material, the inclination angle of each groove with respect to the roll axis in the depth direction is the same as the above-mentioned intersection angle γ in the direction of the material exit side. Form a slope at an angle. That is, when the fins are formed on the material surface so as to be inclined at a predetermined angle, the intersecting angle γ and the inclination angle of each groove with respect to the roll axis in the depth direction are made different. By the way, the above-mentioned groove width means the groove width seen in the material axis direction at each roll setting angle.

Manufacturing of screws using the rolling mill configured as described above is carried out as follows.

First, a solid metal material 4 having a circular cross section and an outer diameter D ₁ larger than the outer diameter D _F (see FIG. 2) of the screw to be manufactured is selected. The size of D ₁ is
It is preferable that D _F be approximately 1.1D _F <D ₁ <1.3D _F.
Next, the selected metal material 4 is heated in a heating furnace (not shown) to a predetermined temperature, for example, 1100° C. in the case of medium carbon steel, and then transferred to a cross-type inclined rolling mill having rolls as described above. As a result, the metal material 4
It is rolled as shown in the figure.

FIG. 3 is a diagram showing the process in order, and the arrow in the diagram indicates the direction of the load applied to the metal material 4. When rolling of the metal material 4 (see Figure 3) is started in the inclined rolling mill, the metal material 4 is bitten by the rolling rolls 1, 2, and 3 in sequence, and then rolled by them at three locations in the circumferential direction. {See Figure 3}, it advances while rotating around its axis. Therefore, subsequent rolling is performed in a spiral manner, and the rolled metal material 4 advances toward the roll exit side.

Then, sequential rolling by three rolls {third
The inside of the rolled portion is stretched in the axial direction, thereby widening the fin spacing. Since the roll is designed so that the grooves that contribute to the next rolling are placed in the fins where the interval has widened, the fins are not crushed during rolling, and the fins are taller and thicker, and the fins are wider apart. It can be formed by

Note that if the setting range of the crossing angle γ and the inclination angle β is 0°<γ<15° 3°<β<20° 5°<γ+β<30°, there is a defect inside the metal material 4. There is an advantage in that even if it is removed, it is possible to produce a screw in which it disappears by stretching and rolling according to the method of the present invention.

This is a Japanese Patent Application Publication No. 59/1999, which the present applicant has already applied for.
No. 4902, and if the present invention is applied to this, even metal materials 4 with defects can be processed without causing the Mannesmann fracture peculiar to inclined rolling.
A high quality rod 5 with spiral fins as shown in FIG. 4 can be manufactured.

The reason why a cross-type inclined rolling mill with three or four rolling rolls is used is that when the number of rolling rolls is reduced to two, a rotary forging effect (so-called Mannesmann effect) peculiar to inclined rolling acts, and for example, inclusions This is because cracks tend to occur in the center of the metal material, starting from porosity or porosity. Therefore, if three or more rolls are required to reduce a solid metal material by inclined rolling, the above-mentioned rotary forging effect can be suppressed if the number of rolls is actually three or more. .

On the other hand, as the number of rolls increases, the set gap cannot be made smaller because adjacent rolls come into contact with each other, and when there are more than five rolls, the structure of the rolling mill becomes complicated, and the roll diameter and the material diameter also increase. Since it is geometrically impossible to increase the diameter of the roll shaft, the rigidity of the mill and the strength of the roll shaft decrease.
Therefore, in practical terms, it is appropriate to set the number of rolls to three to four.

[Numerical example]

A solid circular cross-section metal material of SUS304 with an outer diameter of 70 mmφ is hot-rolled, and the fin spacing is 20 mm.
Outer diameter: 60mmφ, fin bottom diameter: 30mmφ 4th
A rod 5 with spiral fins as shown in the figure was manufactured.

The manufacturing conditions are: rolling roll inclination angle β: 8°, crossing angle γ: 2°, rolling roll rotation speed: 100 rpm, rolling temperature: 1100°C, rolling roll material: SCM440, roll diameter: 180 mmφ, rolling roll inlet conical half angle α :
14.5°, groove spacing on the inlet side: 11.0mm, groove spacing on the exit side: 20.0mm. In addition, in the middle, the interval was made to gradually widen from the inlet to the outlet in accordance with the elongation and twisting of the material. As a result, according to the present invention, it was possible to manufacture a high-fin screw shaft with a fin spacing of 20 mm and a fin height of 15 mm, which was conventionally impossible to manufacture by rolling.

Example 2 This example is a method suitable for forming thick and low spiral protrusions, and the width of the annular groove formed on the roll from the input side to the output side is constant, and the groove depth The pitch of the grooves is the same as in the first embodiment shown in Figs. 1 to 4, so that the depth of the grooves becomes deeper from the entry side to the exit side, and the interval between the grooves, that is, the pitch, becomes wider. It is set as follows.

The case where the number of rolling rolls is three will be specifically explained below.

Fig. 5 is a front view seen from the - line direction of Fig. 6 (rolling roll grooves are omitted), Fig. 6 is a partially enlarged side view taken along the - line of Fig. 5, and Fig. 7 is a pass line - line. FIG. 2 is a schematic side view (roll grooves are omitted) showing a tilted state of the roll relative to the roll. Three cone-shaped rolling rolls 11, 12, 13 constituting the inclined rolling mill are arranged at equal intervals around the pass line.
2 and 13 have gorge parts 11a and 12 at the exit end.
a, 13a, gorge parts 11a, 12a, 1
3a, the entrance side of the metal material 14 is gradually reduced in diameter toward the shaft end, and the exit side is expanded to form approximately truncated conical inlet faces 11b, 12b, 13b and outlet faces 11c, 12c, 13c. It is equipped with The exit surfaces 11c, 12c, and 13c are pass lines.
The distance from the pass line to the gorge portions 11a, 12a, 13a is made to match the distance from the pass line to the line, and the inlet faces 11b, 12b, 13b are positioned on the upstream side in the moving direction of the metal material 14, and further rolling is performed. Intersection O between the axis Y-Y of the rolls 11, 12, 13 and the plane including the gorge parts 11a, 12a, 13a
(hereinafter referred to as roll setting center) are arranged at approximately equal intervals around the pass line of the metal material 14 on the same plane perpendicular to the pass line. The axial center line Y-Y of each rolling roll 11, 12, 13 is centered around the roll setting center O in relation to the pass line of the metal material 14, as shown in FIG. 6 and 7, the front shaft end is inclined at an inclination angle β toward the same side as the circumferential direction of the metal material 14. It is tilted only. roll 11,1
2 and 13 are each connected to a drive source (not shown), and are driven to rotate in the same direction as indicated by arrows in FIG.

Note that it is desirable that the roll shaft holding mechanism be of a dual support type. If the roll shaft is of a double-sided type, the accuracy of the outer diameter of the screw must be ±0.2.
%, whereas in the case of a cantilever type, the mill rigidity is low, so the dimensional accuracy of the screw outside diameter is ±
This is because it worsens to 0.7%.

A plurality of annular grooves, for example, 5 to 7 annular grooves are formed on the outer circumferential surface of the rolled portion, that is, the portion where the distance between the outer circumferential surface of the rolling rolls 11, 12, and 13 and the pass line is smaller than the radius of the outer circumference of the metal material 14. are spaced apart by an appropriate length in the axial direction, and shifted in phase by 1/3 rotation in the circumferential direction. The positions, intervals, widths, and depths of the grooves are different between the rolling rolls 11, 12, and 13, and the groove spacing is different in the axial direction of each rolling roll 11, 12, and 13, and the groove width is also different between the rolling rolls 11, 12, and 13. is assumed to be approximately constant at the groove bottom.

The position and spacing of the grooves are determined depending on the height, spacing, and number of threads of the thread, which is a spiral protrusion to be formed, and the conical half angle α and inclination angle β of the rolling rolls 11, 12, and 13 related to these. , intersection angle γ, etc. are determined. The positions of the grooves are different between the rolling rolls 11, 12, 13.
is the amount of stretching of the metal material 14 from the inlet side to the outlet side,
The interval is gradually widened according to the amount of twist of the metal material 14, and the pitch of the grooves is kept constant on the reeling surface on the exit side from the gorge parts 11a, 12a, 13a.

The groove spacing (pitch) from the inlet side to the gorge parts 11a, 12a, 13a is longer from the inlet side to the outlet side in consideration of elongation and twisting of the material during rolling, and this range is as follows: It is.

0.25P ₂ <P ₁ <0.85P ₂ However, P ₂ : Outlet groove spacing P ₁ : Inlet groove spacing If it is outside this range, the reduction may be too light and sufficient thread height cannot be obtained, or the reduction may be too strong. During rolling, curvature and shape defects may occur.

As a result, the threads emerging from the grooves of one rolling roll are guided to the grooves of the next rolling roll, and are successively shaped to obtain a trapezoidal thread 15 as a screw.

FIG. 8 is a diagram showing this process in sequence, and the arrow in the diagram indicates the direction of the load applied to the metal material 14.
When the metal material 14 (see FIG. 8) starts rolling in the inclined rolling mill, the metal material 14 is rolled by the rolling rolls 11 and 1.
2 and 13, and then rolled at three locations in the circumferential direction by them (see Figure 8), and then rolled along the pass line in a so-called spiraling state, rotating around the axis. Proceed to the exit side.

Then, sequential rolling by three rolls {8th
The roll is designed so that the inside of the rolled part stretches in the axial direction, thereby widening the thread spacing, and grooves that contribute to the next rolling are located in the thread threads where the spacing has widened. As a result, the threads are not crushed during rolling, and the width of the groove bottom is always equal to the width of the top of the thread to be formed, and only the root portions of the thread are rolled down one after another. Therefore, it is possible to form screw threads with high dimensional accuracy and without curvature or flaws during rolling. This makes it possible to manufacture trapezoidal screws 15 with relatively thick threads and long pitches with high precision and good surface quality.

Numerical example 1 Outer diameter: 55mmφ, material: S45C, solid circular cross section metal material, hot rolled, thread spacing: 14
A trapezoidal screw with an outer diameter of 55 mmφ and a screw root diameter of 39 mmφ was manufactured. The manufacturing conditions are: rolling roll inclination angle β: 5°, rolling roll crossing angle γ: 1°, rolling roll rotation speed 100 rpm, rolling temperature: 1000°C, rolling roll material: SCM440, rolling roll diameter: 180 mmφ, rolling roll inlet. Cone half angle α: 12.5°.

Note that the groove spacing is P ₁ = 10.5 mm at the entrance, and P ₂ = 10.5 mm at the exit.
The distance was set at 14.0 mm, and the interval in the middle part was gradually widened from the inlet to the outlet in accordance with the elongation and twist of the material. In addition, the area from the gorge to the exit side was a finished part of the product shape, and the groove width was kept constant. The groove spacing was set from the inlet to the gorge and widened toward the gorge. The shape of the manufactured trapezoidal screw was good.

Numerical Example 2 The metal material was manufactured under the same conditions as Numerical Example 1, with an outer diameter of 65 mmφ. In this case as well, the shape of the trapezoidal thread was good.

In both numerical examples 1 and 2, the groove bottom width is constant at 5.0 mm.
The angle of the groove side wall is relative to the direction perpendicular to the roll axis.
The angle was 16° on the entry side and 14° on the exit side. As a result, by adding a roll intersection angle of 1°, a trapezoidal shape is formed with both sides having an open angle of 15°. Threads are low;
In addition, in the case of a trapezoidal screw with a large thread thickness, it is possible to sufficiently process the thread even if the rolling roll groove width is constant from the entry side to the exit side, and the thread side surface cannot be rolled down excessively during rolling. It was possible to suppress the rash and rough skin caused by this process, and improve the texture and dimensional accuracy of the finished product.

In addition, in the first and second embodiments described above, explanation has been given of a configuration in which large-diameter metal materials 4 and 14 are used as materials for the screw barrel with spiral fins and the trapezoidal screw, but the product is not limited to this. It is also possible to use materials of the same diameter.

〔effect〕

As detailed above, in the case of the present invention, a plurality of annular grooves for forming screws are provided in the circumferential direction of the outer circumferential surface of the rolling part at intervals that gradually become wider from the input side to the output side, and each groove width is constant or from the input side. Since the circular cross-section metal material is elongated and rolled using a cross-type inclined rolling mill with rolling rolls that are narrower on the exit side,
The present invention has excellent effects such as being able to freely set the height, thickness, and pitch of the helical protrusions, and making it possible to manufacture screws according to the application.

[Brief explanation of drawings]

FIG. 1 is a front view showing the implementation state of the first embodiment of the present invention, FIG. 2 is a partially enlarged side view taken along the - line in FIG. 5 is an external view of the screw manufactured by the method of the present invention, FIG. 5 is an implementation state of the second embodiment of the present invention, and FIG.
The figures are a partially enlarged side view taken along the - line in Fig. 5, Fig. 7 is a side view showing how the rolling rolls are arranged with respect to the pass line, Fig. 8 is an explanatory diagram of the rolling contents of the second embodiment, and Figs. 9 and 12. 10 and 13 are partially enlarged side views, respectively. FIGS. 11 and 14 are explanatory diagrams of the rolling details of the conventional method. FIG. 15 is an explanatory diagram of problems in the conventional technique. It is. 1, 2, 3... Rolling roll, 4... Metal material, 5
...rod with spiral fin, 11, 12, 13
...Rolling roll, 14...Metal material, 15...Trapezoidal screw.

Claims (1)

[Claims] 1. A method for manufacturing a screw from a solid circular cross-section metal material by inclined rolling, wherein the outer diameter of the solid circular cross-section metal material is selected to be the same as or larger than the outer diameter of the screw. Then, a plurality of conical rolling rolls are formed in the circumferential direction of the outer peripheral surface at intervals where the annular grooves that form the spiral protrusions gradually widen from the entry side to the exit side, and three conical rolling rolls are equally spaced around the pass line. A method for manufacturing a screw, comprising hot elongation rolling of the circular cross-section metal material using four cross-type inclined rolling mills. 2. In a method for manufacturing screws from a solid circular cross-section metal material, a plurality of annular grooves forming spiral protrusions are formed in the circumferential direction of the outer peripheral surface of the rolling part at intervals that gradually become wider from the input side to the output side. , using a cross-type inclined rolling mill in which three or four rolling rolls, each of which has a groove width narrower from the entry side to the exit side, are arranged facing around the pass line, to produce the circular cross-section metal material. 1. A method for manufacturing a skrill, which comprises hot elongation rolling. 3. The method of manufacturing a screw according to claim 2, wherein the outer diameter of the solid circular cross-section metal material is larger than the outer diameter of the screw.