JP6805592B2 - How to cut the rubber strip - Google Patents

Description

The present invention relates to a method for cutting a rubber strip that can accurately cut a rubber strip transported on a transport belt while transporting the rubber strip.

In recent years, from the viewpoint of improving productivity, a so-called strip wind type tire forming method has been proposed in which rubber members such as tread rubber and sidewall rubber are formed by using a long strip-shaped unvulcanized rubber strip (for example). See Patent Document 1).

In this strip wind method, an unvulcanized rubber strip is conveyed by using a conveying belt and continuously wound spirally on a rotating drum to form a rubber member having a desired cross-sectional shape. Therefore, in the strip wind method, a cutting means for cutting the rubber strip while transporting it on the transport belt is required at the end of winding.

As shown in FIG. 6, the conventional cutting means a includes a flat plate-shaped cutter b rotatably supported around the axis J. Then, the cutter b is rotated once at a rotation speed substantially equal to the transport speed of the rubber strip G to cut the rubber strip G while transporting it.

However, when the rubber strip G is cut all at once over the entire width, the tension acting on the rubber strip G until then disappears momentarily. Therefore, the rear end Ga of the rubber strip G being wound around the drum becomes free and tends to meander, which causes a problem that the sticking accuracy to the drum is impaired.

On the other hand, Patent Document 2 below proposes to provide a V-shaped notch at the center of the cutter in the width direction and at the edge of the cutting edge. In this case, when the cutter b is lowered, as shown in FIG. 7A, the rubber strip G is not completely cut, and the front and rear (front and back of the transport direction) of the cutting position P are still thin connecting portions. It is connected by g. Then, as shown in FIG. 7B, as a result of the rear end portion Ga, which is rubber on the front side of the cutting position P, being pulled by winding around the drum, the connecting portion g gradually extends and breaks.

That is, the rubber strip G is cut while gradually reducing the tension. Therefore, it is possible to reduce the meandering of the rear end Ga. However, as shown in the figure, as a result of the connecting portion g being formed in the center of the rubber strip G in the width direction, the pulling causes the connecting portion g toward the width direction center side toward the width direction side portions Ga1 in the rear end portion Ga. It causes a new problem that curl occurs and causes deformation such as breakage.

Japanese Unexamined Patent Publication No. 2006-159443 Japanese Unexamined Patent Publication No. 2014-217999

Therefore, the present invention provides a method for cutting a rubber strip that can suppress deformation such as meandering at the rear end portion and bending toward the center in the width direction at the rear end portion when cutting while transporting the rubber strip. Is an issue.

The present invention is a method for cutting a rubber strip, which cuts a long strip-shaped rubber strip while transporting it on a transport belt by a cutting means.
The cutting means includes a flat plate-shaped cutter that is rotatably supported around an axis extending at right angles to the transport direction and in the width direction of the rubber strip.
In addition, the cutter has a cutting edge edge parallel to the axis at the outer edge on the outer edge in the radial direction of the rotation.
It is characterized in that a plurality of notches are provided at the edge of the cutting edge.

In the method for cutting a rubber strip according to the present invention, it is preferable that the plurality of notches are arranged at symmetrical positions about the center of the width of the cutter.

In the method for cutting a rubber strip according to the present invention, the total width W1 of the notch portion W1 is preferably 5 to 15% of the width Wg of the rubber strip.

In the method for cutting a rubber strip according to the present invention, the cutout portion preferably has a semicircular shape.

In the present invention, as described above, a plurality of notches are provided at the edge of the cutting edge of the cutter. Therefore, the front and back of the cutting position of the rubber strip are connected by a connecting portion of a plurality of thin rubber pieces. Therefore, the rubber strip can be cut while gradually reducing the tension of the rubber strip, and the occurrence of meandering at the rear end can be reduced. Further, since the front and rear of the cutting position are connected by a plurality of connecting portions, both side portions in the width direction of the rear end portion are less likely to curl, and deformation such as bending can be suppressed.

It is a perspective view which shows an example of the strip wind apparatus which adopted the cutting method of the rubber strip of this invention. It is sectional drawing which shows the cutting means. It is an exploded perspective view which shows the cutting means. It is a front view which shows the cutter. (A) and (B) are plan views explaining a state in which a rubber strip leads to cutting. It is a side view which conceptually explains the conventional cutting means. (A) and (B) are plan views explaining problems in other conventional cutting means.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a perspective view showing an example of a strip wind device 1 that employs the method for cutting a rubber strip of the present invention. In the strip wind device 1 of this example, a long strip-shaped unvulcanized rubber strip G is continuously spirally wound around a rotating drum 2, whereby a tire such as tread rubber or sidewall rubber is used. Form a rubber member.

The strip wind device 1 includes a conveyor 4 having a conveyor belt 3 and a cutting means 5 for cutting the rubber strip G conveyed on the conveyor belt 3. The conveyor 4 is supported by the support portion 6.

In this example, the support portion 6 is
(A) A lateral moving table 6A that can move in the lateral direction parallel to the axis 2i of the drum 2 and
(B) A vertical moving table 6B supported on the horizontal moving table 6A so as to be movable in the vertical direction perpendicular to the axis 2i.
(C) The vertical moving table 6B is provided with a swivel table 6C that is rotatably supported around the vertical swivel axis 6i.

In this example, the conveyor 4 includes a frame 7 supported by the swivel base 6C. Further, the transport belt 3 is guided around the transport direction Fx by a plurality of guide rollers 8 supported by the frame 7.

The cutting means 5 cuts the rubber strip G supported by the frame 7 and transported on the transport belt 3 while transporting the rubber strip G. As shown in FIGS. 2 and 3, the cutting means 5 includes a flat plate-shaped cutter 10. In this example, the cutter 10 is rotatably supported via the cutter holder 11 around an axial center J extending at right angles to the transport direction Fx and in the width direction Fy of the rubber strip G. FIG. 2 shows a reference state Y in which the cutter 10 is perpendicular to the rubber strip G and the cutting edge edge 10T faces downward.

As shown in FIG. 3, the cutter holder 11 of this example has a rectangular block-shaped base 12, and a support shaft 13 forming the axial center J is provided on both side surfaces 12S1 of the base 12 in the width direction Fy. It is protruding. A cutter mounting surface 14 parallel to the axis J is formed on the front surface 12S2 of the substrate 12 facing forward in the rotation direction. Each support shaft 13 is pivotally supported by, for example, a portal frame 15 (shown in FIG. 1) attached to the frame 7 via a bearing or the like, and a motor M is connected to one of the support shafts 13.

Next, the cutter 10 has a rectangular plate shape fixed to the cutter mounting surface 14. In this example, the case where the cutter 10 is fixed to the cutter mounting surface 14 by bolts 16 is shown. The cutter 10 is provided with a sharp-edged edge 10T parallel to the axis J at the outer edge, that is, the lower edge in the reference state Y, which is the outer edge in the radial direction of rotation.

A plurality of cutout portions 18 are provided at the cutting edge edge 10T. In this example, as shown in FIG. 4, a case where two notch portions 18 are formed is shown. It is preferable that the plurality of cutout portions 18 are arranged symmetrically with respect to the width center Co of the cutter 10. The width center Co of the cutter 10 substantially coincides with the width center of the rubber strip G.

When cut with such a cutter 10, the rubber strip G is not completely cut as shown in FIG. 5 (A), and the front and back of the cutting position P are connected by a connecting portion g of a plurality of thin rubbers. ing. As shown in FIG. 5B, the connecting portion g gradually extends and becomes thinner and breaks when the rear end portion Ga, which is rubber on the front side of the cutting position P, is pulled by winding around the drum 2. To reach. Therefore, the rubber strip G is cut while gradually reducing the tension, and the occurrence of meandering at the rear end Ga is reduced.

Further, since the front and rear of the cutting position P are connected by a plurality of connecting portions g, it becomes difficult for both side portions Ga1 in the width direction of the rear end portion Ga to curl, and deformation such as bending can be suppressed.

When the notch portion 18 is arranged at an asymmetrical position, when the connecting portion g breaks, the rear end portion Ga tends to be displaced in the width direction Fy, which may reduce the sticking accuracy to the drum 2. ..

As shown in FIG. 4, the total sum ΣW1 of the width W1 of the notch portion 18 at the cutting edge edge 10T is preferably 5 to 15% of the width Wg of the rubber strip G. If it is less than 5%, the effect of reducing meandering by the connecting portion g is not sufficiently exhibited. On the contrary, when it exceeds 15%, the change in tension when the connecting portion g is pulled and breaks becomes abrupt, and similarly, the effect of reducing meandering is not sufficiently exhibited. The height H1 of the cutout portion 18 is larger than the thickness t of the rubber strip G.

As the shape of the cutout portion 18, a semicircular shape is preferable because an even force is distributed when the remaining rubber portion is pulled.

Although the particularly preferable embodiments of the present invention have been described in detail above, the present invention is not limited to the illustrated embodiments and can be modified into various embodiments.

In order to confirm the effect of the present invention, a rubber strip was spirally wound around the drum using the strip wind device having the structure shown in FIG. 1 to form a tire rubber member. Then, at the end of winding, the state of meandering at the rear end when the rubber strip was cut using the cutter having the specifications shown in Table 1 and the state of curl-like bending deformation were inspected. Except as shown in Table 1, the specifications are substantially the same.

(1) Occurrence of meandering and bending deformation:
The number of times of meandering and the number of times of bending deformation when 50 tire rubber members were formed were compared. The lower the number, the better. As the rubber strip, a rubber strip having a width of Wg = 23 mm and a thickness of t = 1.0 mm was used.

As shown in Table 1, in the examples, it can be confirmed that the occurrence of meandering and the occurrence of bending deformation at the rear end of the rubber strip can be suppressed.

3 Conveying belt 5 Cutting means 10 Cutter 10T Cutting edge edge 18 Notch g Connecting part Co Width center G Rubber strip J Axis center

Claims (5)

A method of cutting a rubber strip, which cuts a long strip-shaped rubber strip while transporting it on a transport belt by a cutting means.
The cutting means includes a flat plate-shaped cutter that is rotatably supported around an axis extending at right angles to the transport direction and in the width direction of the rubber strip.
In addition, the cutter has a cutting edge edge parallel to the axis at the outer edge on the outer edge in the radial direction of the rotation.
A plurality of notches are provided at the edge of the cutting edge .
A method for cutting a rubber strip, wherein the plurality of notches are arranged at symmetrical positions about the center of the width of the cutter . The method for manufacturing a tire according to claim 1 , wherein two or four notches are provided on the edge of the cutting edge . The method for cutting a rubber strip according to claim 1 or 2 , wherein the width center of the cutter coincides with the width center of the rubber strip. The method for cutting a rubber strip according to any one of claims 1 to 3 , wherein the total width W1 of the cutout portion ΣW1 is 5 to 15% of the width Wg of the rubber strip. The method for cutting a rubber strip according to any one of claims 1 to 4, wherein the cutout portion has a semicircular shape.

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