JPS5837094B2 - rotary shear - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a rotary shear, which is a type of cutting device for corrugated paper, steel plates, etc.

As shown in Figures 1 and 2, the rotary shear has an upper cutter 3 in a rotating upper cylinder 1 and a lower cylinder 2, respectively.
, install the lower cutter 4, upper cylinder 1, lower cylinder 2
When the upper cutter 3 and lower cutter 4 intersect with the rotation of , the plate material 6 being fed by the feed roll 5 is bitten and cut, and the force required for cutting is transferred from the drive motor 7 to the damping gears 8 and 9. It is applied to the lower cylinder 2 through the distribution gears 10 and 11, and further applied to the upper cylinder 1 through the distribution gears 10 and 11.

Note that the distribution gears 10, 11, 12, and 13 are connected to the upper and lower cylinders 1 and 2 so that the upper cutter 3 and the lower cutter 4 always mesh normally.
installed on both sides.

The guillotine type, which is a general cutting method, uses a pair of blades that move parallel to each other and cuts by the shear force applied to the plate material at that time, whereas the rotary shear uses a guillotine type cutting mechanism because the blades rotate. will be specific to different rotary shears.

That is, when the blades rotate, they interfere with each other, so it is not possible to increase the lap margin γ of the blade edge.

(See Figure 3) This also improves sharpness when cutting.
In order to obtain a good cut surface, it is necessary to keep the clearance C between the blades to a minimum, and if this clearance C is large as shown in FIG. 4, the plate material 6 may not be able to be cut.

The maximum clearance that allows cutting at this time is called cutting limit clearance Co.

FIGS. 5 and 6 show models of the cutting mechanism in which the upper knife precedes the lower knife.

The acting forces that the blade receives from the plate material to be cut include a cutting force P and a lateral force F, and the required cutting torque M is required to rotate the cylinder against these acting forces.

This required cutting torque (hereinafter referred to as torque) M has different values for the upper and lower cylinders as shown in the equation below.

Torque of the upper cylinder 1 Torque of the lower cylinder 2 A: Distance between the cutting edge and the shaft center, R: Rotation radius of the cutting edge Further, the torsion angle button of the upper cylinder and the torsion angle θd of the lower cylinder due to the above torque are expressed as follows. .

Here, l: Distance from one end of the cylinder to the cutting position G: Transverse elastic modulus of the cylinder ■p: Polar moment of inertia of the cylinder (Ipu
= Ipd = Ip ) By substituting equations (1), (2), and (3) into equations (4) and (5), the torsion angle difference Δθ between the upper cylinder 1 and the lower cylinder 2 is determined.

Furthermore, when the clearance C between the blades is determined, the equation (7) is qualitatively illustrated as shown in FIG. 7.

In other words, the torsion angle of the lower cylinder 2 is larger than the torsion angle of the upper cylinder 1, resulting in a torsion angle difference Δθ, whose value is equal to the center of the cylinder (1=lo/
It is maximum when 2).

Conventional rotary shears have not been designed to suit this cutting mechanism and have had various problems.

In other words, as a method of keeping the clearance C between the upper and lower blades to a minimum in order to have almost the same strength between the upper and lower blades, improve sharpness during cutting, and obtain a good cut surface, the conventional method is shown in Figure 1. Set the distribution gears IL12, 13, and 14 to 2 as shown.
This was done by stacking the blades and shifting them relative to each other to prevent backlash between the gears, or by adjusting the tightness of the bolts that attach the blade to the cylinder.

However, with only these methods, it is difficult to constantly maintain the clearance C at a minimum value due to loosening of bolts, etc., and there are also problems such as the need to repeatedly perform complicated adjustments as necessary.

Furthermore, when tightening the bolts, excessive preload is applied so that the cutting edges come into close contact with each other to reduce the clearance C, but this causes significant wear on the cutting edges.

The present invention is a shear of a type that rotates blades attached to each of a pair of cylinders and inserts and cuts a plate material between the blades, and is characterized in that the mechanical strength of the leading blade is weaker than that of the other blade, The objective is to provide a rotary shear that eliminates the drawbacks of the conventional technology and that automatically minimizes the clearance between cutting tools at all times and enables good cutting without the need for complicated adjustments. It is something.

The present invention is constructed as described above, and its operation will be explained next.

As can be seen from the explanation of the cutting mechanism of the rotary shear above, if the upper and lower cylinders have the same mechanical strength, the trailing blade will twist more than the leading blade (which contacts the plate first), which will cause the blade to twist more. It can be understood that this difference is a factor in increasing the clearance between the blades.

In the present invention, this difference in torsion is utilized, that is, the mechanical strength of the leading blade is made weaker than the other, so that the torsion of the leading blade is the same as the torsion of the other blade during cutting. Cutting is performed by always reducing the clearance between the two blades.

In this way, in the present invention, by making the mechanical strength of the preceding blade weaker than that of the other blade, the clearance between the two blades during cutting can be automatically kept to a minimum, so cutting can always be performed well, and it is also possible to This eliminates the need for complicated clearance adjustments.

Furthermore, there is no need to apply excessive preload to the cutting edge as in the conventional method, and wear on the cutting edge is reduced.

The present invention will now be described in detail with reference to the most preferred embodiment shown in FIGS. 8 to 11.

In this embodiment, the diameter d of the upper cylinder 1 and the lower cylinder 2 is changed to increase the difference in rigidity between the two cylinders, thereby canceling out the difference in torsion between the blades attached to both cylinders that acts during cutting. The other structure is the same as the conventional one.

In this embodiment, the upper knife 3 precedes the lower knife 4.

From formulas (1), (2), (4), and (5), upper cylinder 1
The torsion angle difference Δθ between the lower cylinder 2 and the lower cylinder 2 is as follows.

On the other hand, according to previous experiments, there is a certain relationship between the cutting force p and the lateral force F, which can be roughly expressed as the following equation: where λ: lateral force ratio In equation (8), Δθ is O By doing so, the clearance C between the blades can be eliminated, and for this purpose, the right side of equation (8) should be made equal to or less than O.

By substituting equation (9) into equation (8), the following equation can be obtained as a condition for making the clearance O or less.

Note that when Δθ is negative, it means that the upper knife 3 is pressed against the lower knife 4.

Here, Pd-:Pu=P, . Ad: A1-:R in Au
Substituting u=R into equation (10) gives Rd where a>λR.

Also, the polar moment of inertia of the cylinder Ip Therefore, the set becomes as follows.

That is, it is sufficient to make a difference in the diameter d of the cylinder so as to satisfy the equation (13).

As an example, the calculations for a cardboard cut-off device are as follows.

Now assume each value as follows. By substituting (14) into equation 03), that is, by making the diameter dd of the lower cylinder 2 1.32 times or more the diameter du of the upper cylinder 1, the clearance C between the blades can be eliminated.

Furthermore, the cutting tool of a rotary shear is usually provided with a rake (slope) as shown in FIG. 10, and this rake causes the rotation radius R of the cutting edge and the distance A between the cutting edge and the axis to vary in the axial direction.

In this case, the conditions for eliminating the clearance between the blades can be expressed as the following equation using the αυ equation.

Equation (l7) is shown qualitatively in FIG. 11.

That is, in order to eliminate the clearance between the blades, the cutting position changes in the axial direction due to the rake, and the rigidity of the blades and cylinders should be changed in the axial direction so as to satisfy the αD equation.

Note that in this example, the diameter of the cylinder is changed to make the mechanical strength of the upper cylinder and the lower cylinder different, but the invention is not limited to this, and for example, the diameter of the shaft on which the cylinder is attached can be made different. The purpose can also be achieved by providing a difference in the strength of the distribution gears of the upper and lower cylinders, and further by providing a difference in the strength of the upper and lower cutters themselves.

In this way, according to this embodiment, by making the diameter of the lower cylinder larger than that of the upper cylinder, the rigidity of the preceding upper cylinder is made smaller than that of the lower cylinder, so that the torsion of the upper cylinder is greater than that of the lower cylinder during cutting. Therefore, the upper cutter is always in close contact with the lower cutter, and the clearance between the cutters can always be kept to a minimum, allowing good cutting to be performed at all times.

In addition, this phenomenon occurs naturally in response to changes in cutting force, so there is no need to apply excessive preload to the blade as in the past, reducing wear on the tooth tips, and eliminating the need for complicated clearance adjustments. No longer needed.

[Brief explanation of drawings]

Fig. 1 is a schematic explanatory diagram of a conventional rotary shear, Fig. 2 is a central sectional view, Fig. 3 is an explanatory diagram showing cutting when the clearance is small, and Fig. 4 is an explanatory diagram showing cutting when the clearance is large. , Fig. 5 is a front view explaining the cutting mechanism of the rotary shear, Fig. 6 is an explanatory diagram of each force relationship explaining the cutting mechanism of the rotary shear, and Fig. 7 shows the torsion of the upper and lower cylinders of the conventional rotary shear. An explanatory diagram showing the relationship in the axial direction of the clearance between the blades due to the angle and the difference thereof, FIGS. 8 to 11 show an embodiment of the present invention, FIG. 8 is a schematic explanatory diagram thereof, FIG. 9 is the top, An explanatory diagram showing the relationship between the torsion angle of the lower cylinder and the clearance between the cutters in the axial direction. Fig. 10 is an explanatory diagram showing the distance relationship when the cutter has a rake. Fig. 11 shows the clearance when the cutter has a rake. Ipd/I required to
FIG. 2 is an explanatory diagram showing the relationship between pu and l/lo. 1...Upper cylinder, 2...Lower cylinder, 3...Upper knife, 4...Lower knife,
6...Plate material.

Claims (1)

[Claims] 1. A rotary shear of a type that cuts a plate by rotating blades attached to each of a pair of cylinders and inserting the blades between the blades, in which the mechanical strength of the leading blade is weaker than that of the other blade. .