JPH10179952A - Air nipper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain small and light air nippers capable of cutting materials of a big diameter quickly and easily by producing greater cutting force while the center part of the cutting material is cut. SOLUTION: A pair of nippers are journaled at the center in an X shape, on the front end of a cylinder-shaped holder 1 which is closed at the rear, through a fulcrum pin 18. The nippers are constituted of a front big tapered cone interior 21 and a rear small tapered cone interior 22, which taper toward the rear end, from the front end of a piston, including both rear ends of the nipper inserted in the rear of the cylinder 1, which is butted into an inside of coaxial two-layered cones, which is a rotation surface of a folding line-like generating line. Compressed air is led from the rear of the holder to move the piston forward against the spring, thereby the nippers are closed against the spring to cut the work. Then the internal air in the holder is discharged to return the piston and nippers to the open positions through the spring. The folding line-like generating line is a different-shaped conical surface having the generating line of a smooth quadratic curve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air nipper for cutting wood, plastic, metal and the like by using compressed air as power.

[0002]

2. Description of the Related Art Air nippers powered by compressed air are:
Conventionally, for example, as shown in a vertical sectional view of FIG. 6, a screw 7 is cut into the inner surface of the rear end of the cylindrical body 1 having an open front end.
The center fulcrum of the cutting blades 16, 17 of the nipper blades, which form a pair of upper and lower portions and intersect in an X-shape, is provided at the front end of a cylindrical holder formed by screwing the end plate 3 having a screw 8 on the outer periphery. The holder body 1 and the end plate 3 are sealed by an O-ring 10 and a piston 2 is inserted in the rear part of the holder. The main body 1 and the piston 2 are sealed by an O-ring 9 to keep the air chamber 4 airtight, and the piston 2 is slidable forward and backward as shown by arrows A and B. That is, the ventilation hole 5 at the rear end of the holder
When compressed air is introduced into the air chamber 4 from above, the piston 2 is pushed forward, and the nipper slidably abuts the conical inner surface 6 expanding forward of the central concave hole formed in the front end of the piston 2. The hemispherical portions 14, 15 at the rear ends of the eleven handles 12, 13 are pushed by the conical inner surface 6, and the rear ends of the handles 12, 13 move in the direction of the arrow X approaching each other. At this time, the cutting blades 16 and 17 of the nipper 11 close and mesh in the arrow Y direction with the fulcrum horizontal pin 18 as a fulcrum to cut wood, plastic, metal and other materials to be cut indicated by chain lines. Here, the cutting force F of the nipper is obtained by the following equation (1). F = (π / 4) · c ² · P · (1 / tan θ) · (L ₂ / L ₁ ) · d (1) where c: piston outer diameter, P: compressed air pressure, θ :
Cone angle, L ₁ : length between fulcrum and tip of tooth tip, L ₂ : length between fulcrum and hemispherical part of handle, d: energy loss rate (≒ 0.
7) After the cutting, the compressed air in the air chamber 4 is extracted from the ventilation hole 5 so that the piston 2 is pushed back in the direction B by the compression spring 19. At the same time, the nipper 11 is moved in the direction opposite to the arrow X by the compression spring 20 elastically mounted between the handles 12 and 13, and the blade 1
6 and 17 are also opened to end the cutting process.

[0003]

A conventional air nipper of this type is used because it is small and lightweight and easy to handle. However, only one conical surface of the central concave hole of the piston is provided. The cutting force is constant. Therefore, when cutting a material having a circular cross section, the cutting line becomes longer as the cutting blade approaches the center of the cross section of the material to be cut, and a large cutting force is required. For this reason, when the diameter of the material to be cut is large, it is inevitable that inconvenience such as inability to cut occurs.

The present invention has been proposed in view of such circumstances, and it is possible to cut a large-diameter workpiece quickly and easily by generating a large cutting force when cutting a central portion. An object of the present invention is to provide a compact, lightweight, powerful and economical air nipper.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, a central portion is pivotally supported by a fulcrum pin on a front end of a cylindrical holder having a rear end closed and a front portion is formed. A central concave hole having a conical inner surface that reduces the diameter toward the rear end at the front end of a piston inserted in the rear of the holder by pivotally supporting a pair of nippers having a handle at the rear with a cutting blade. Recessed,
The rear end of the pair of nippers is in contact with the large diameter portion of the inner surface of the cone of the piston, and compressed air is introduced from the rear end of the holder to move the piston forward against the spring. In the air nipper, the pair of nippers are closed against the spring, the workpiece is cut, and then the compressed air inside the holder is released to return the piston and the nippers to the open position by the springs. The piston has a front large taper cone inner surface and a rear small taper cone inner surface, and a coaxial two-stage cone inner surface, which is a rotational surface of a folding line, is formed as a two-stage cone inner surface. And

According to a second aspect of the present invention, in the first aspect, the inner surface of the two-step cone formed by the fold line of the piston is formed by a rotation surface having a quadratic curve extending smoothly along the fold line as the base line. It is characterized in that it has a modified conical inner surface.

According to a third aspect of the present invention, in the first or second aspect, the radius of the center concave hole of the piston which abuts on the front end of the cross section of both rear ends of the pair of X-shaped nippers is larger than the radius of the center concave hole. It is characterized by having a short radius radius so that both can be in line contact.

According to a fourth aspect of the present invention, in the first or second aspect, a rectangular cross section formed at both rear ends of the pair of X-shaped nippers and an inner surface of a center concave hole of the piston have an axial plane. And a concave groove having a rectangular cross section, which is engraved from the front end opening to the rear end of the closing along the rear end, and the rectangular cross section of the rear end of the nipper is loosened.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view showing the internal structure of a first embodiment, FIG. 2 is a longitudinal sectional view showing a second embodiment, FIG.
FIG. 4 is an exploded vector diagram showing a reaction force component acting on the contact, which is a part III in FIG. 2, and FIGS. 4 and 5 are longitudinal sectional views showing central concave holes of the pistons according to the third and fourth embodiments of the present invention, respectively. FIG. 3 is a plan view and a cross-sectional view thereof.

First, in the first embodiment shown in FIG. 1, the same reference numerals as those in FIG. 6 denote the same members as those in FIG. 6, and the first embodiment differs from the structure in FIG. It is in the shape of a conical central concave hole in the piston. That is, 2a
Denotes a piston according to the present invention, in which a coaxial two-stage conical surface comprising a front large taper conical inner surface and a rear small taper conical inner surface having different tapers is provided inside the piston 2a, and the conical angle of the small taper conical surface 22 theta ₂ is are smaller than the conical angle theta ₁ of the large tapered outer conical surface 21.

In the nipper having such a structure, when the piston 2a is pushed in the forward direction A by compressed air when cutting a large-diameter workpiece, first, the inner surface of the large taper cone 2
The rear hemispherical portions 14, 15 of the handles 12, 13 of the nipper 11 in contact with 1 slide on the inner surface 21 of the same large taper cone, and the handles 12, 13 move in the direction to close each other. Close and start cutting. Next, when the rear end hemisphere portions 14 and 15 of the nipper pattern start to contact the small tapered conical inner surface 22, the cutting force F increases. As a result, when cutting a large-diameter round bar, the cutting line becomes longer as the cutting blade is closer to the center of the cross section, and even though a large cutting force is required, this can be easily cut. It is.

In this structure, as shown in the second embodiment of FIG. 2, instead of the conical surface forming the central concave hole of the piston 2b being a two-stage conical inner surface, the two-stage conical inner surface is folded. A modified conical inner surface having a quadratic curve which is a rounded parabolic conical surface formed by a rotational surface having a quadratic curve extending smoothly along a linear generating line as a generating line may also be used. A piston having a center concave hole in a rounded conical inner surface instead of such a folding line can also provide substantially the same operation and effect as the above embodiment.

The cutting force by the air nipper in the second embodiment can be obtained as follows. That is, the symbols are determined as follows in FIGS. P: Pressure of compressed air c: Diameter of piston θ: Angle between the tangent of the quadratic curve generating line and the center line at the open end of the modified conical concave hole of the piston L ₂ : Axial component of length oa L ₁ : Length Axial component of sab W: axial thrust of piston F: reaction force of nipper o: fulcrum of nipper a: contact point between rear end of nipper and center concave hole of piston b: force F acting on cutting blade Point of action d: Efficiency count W ₁ : Component force in the direction perpendicular to the slope of piston axial force W W ₂ : Component force in the direction perpendicular to the axis of piston axial force W

In FIGS. 2 and 3, the deformed conical surface of the piston can be treated as a tangent to the contact point a, and the arbitrary inclination angle θ
FIG. 3 shows the relationship between the forces acting on the nippers at the time. Here, regarding the relationship between the contact point a between the nipper and the deformed conical surface and the point of action b of the force F acting on the cutting blade with respect to the fulcrum o of the lever, a, o, b are not necessarily on one straight line. A, o, and b can be regarded as substantially on one straight line as shown in FIG. At this time, a thrust of W / 2 acts on one nipper in the axial direction at the contact point a, and this force is applied to a component W ₁ perpendicular to the slope and a component W ₂ perpendicular to the axis.
W ₂ satisfies equation (2). W ₂ * tan θ = W / 2 (2) Since the rotational moment of the lever with respect to the fulcrum o by W ₂ * L ₂ is balanced with the moment F * L ₁ by the force F acting on the cutting edge, the following equation is obtained. 3) is established. F * L ₁ = W ₂ * L ₂ (3) W is obtained by equation (4) if the reaction force of the spring is ignored. W = π * c ² * p / 4 (4) From equations (2) to (4), F is eventually given by equation (5). F = L ₂ / L ₁ * W ₂ = L ₂ / L ₁ * W / ₂ tan θ = L ₂ / L ₁ * (π * c ² * p / 4) / 2 tan θ (5) A frictional force acts at the contact point a and the fulcrum o,
Reaction force and direction of the component force W ₁ of the spring of ignoring earlier there is always a loss of active ingredients of a force due to not match the direction of the straight line aob. In total, d including efficiency and coefficient
Then, F is finally given by Expression (6). F = L ₂ / L ₁ * (πc ² * p / 4) * d / 2 tan θ (6) From the equation (6), the cutting force F becomes smaller as the inclination angle of the contact point acting on the nipper becomes smaller. It turns out to be big. Cutting force F
Since a good cutting surface can be obtained when the cutting edge becomes large near the end of cutting, it is good to select the inclination angle θ of the inclined surface of the piston so as to be small with respect to the stroke motion of the cutting blade in the cutting end direction.

Here, as shown in FIG. 4, the central concave hole of the piston has a circular cross section as shown in FIG. 4, and rectangular concave grooves are formed at both ends of the circular cross section shown in FIG. A fourth embodiment having a modified circular cross section is considered.

First, the third embodiment shown in FIG. 4 differs from the two-stage conical center concave hole of the piston of the first embodiment shown in FIG. 1 as shown in FIGS. The front end has a large opening at the front end consisting of a large diameter circle, and the rear end has a closed end consisting of a small diameter circle.The gradient in the middle decreases continuously from the front end to the rear end, and the minimum gradient is at the closed rear end. It has a modified conical center hole. The deformed conical surface can be geometrically drawn as a rotation surface having a quadratic curve which is a parabola that smoothly connects the folding line generating lines of FIG. 1 as a generating line and a center line as a rotation axis. Here, as shown in FIG. 4B, the cross-sectional shape of the rear end portion of the nipper 12 is an arc of R ₀ , which is a radius smaller by a small amount ΔR than the radius R at the maximum stroke position of the piston, that is, R ₀ = A radius is given by an arc of R-ΔR. Due to the relationship between the radius R of the irregularly shaped conical surface forming the central concave hole of the piston and the radius R ₀ of the rear end of the nipper 11, line contact between the two is inevitable, but processing of the radius is easy. In addition, since the deformed conical surface and the rear end of the nipper can be brought into rotational contact with each other, wear of both can be prevented.

Next, in the fourth embodiment, as shown in the transverse sectional view of FIG. 5B, the modified conical surface having the circular cross section shown in the longitudinal sectional view of FIG. 3 and the partially enlarged view of FIG. A pair of upper and lower grooves 23 having a rectangular cross-section where the rear end of the nipper 11 is loosely fitted to both ends of the vertical diameter are formed over the entire length of the generatrix conical surface generating line. For this purpose, for convenience of processing, the piston 2c is formed into two parts, an upper half and a lower half, on a horizontal plane passing through the center line, as shown in FIG. An integrated piston is formed by machining a dovetail groove and a dovetail at the joint ends of the halves and slidingly fixing the two in the axial direction so as to fit them. Accordingly, a pair of upper and lower nippers having a flat rectangular cross section of an appropriate depth having a width at which the width of the rear end of the nipper is loosened is provided in the center concave hole formed of the modified conical surface of the completed piston of the fourth embodiment. The rear end guide groove is formed over the entire length of the generatrix of the modified conical surface.

[0018]

According to the first aspect of the present invention, a pair of a cylindrical holder having a closed rear end is pivotally supported at the front end by a fulcrum pin, the front portion is a cutting blade, and the rear portion is a handle. The nipper is pivotally supported in an X-shape, and a central concave hole having a conical inner surface whose diameter is reduced toward the rear end is formed in the front end of the piston inserted in the rear of the holder. The rear end of the pair of nippers comes into contact with the large-diameter portion of the inner surface of the cone of the piston, and compressed air is introduced from the rear end of the holder to move the piston forward against the spring. Is closed against the spring, the work is cut, and then the compressed air inside the holder is released.
In the air nipper in which the nippers are returned to the open position by springs, the piston has an inner surface of a large taper cone at the front and an inner surface of a small taper cone at the rear. The inner surface is formed as a two-step conical inner surface with a concave shape, so that even a large-diameter member to be cut can generate a large cutting force at the time of cutting the center part, so that it can be cut quickly and easily and is small and light. The invention is of great industrial benefit because it provides a powerful and economical air nipper.

According to the invention of claim 2, according to claim 1,
In the above, the inner surface of the two-step cone formed by the fold line of the piston is formed as a modified conical inner surface formed by a rotating surface having a quadratic curve extending smoothly along the fold line as a generating line. As in the invention of the first aspect, even a large-diameter member to be cut can be cut smoothly, quickly and easily because a large cutting force is continuously generated at the time of cutting the central portion, so that it is compact, lightweight, powerful and economical. The invention is of great industrial benefit because it obtains air nippers.

According to the third aspect of the present invention, in the first or second aspect, the radius of the central concave hole of the piston abutting on the front end of the cross section of both rear ends of the pair of X-shaped nippers. By attaching a radius of shorter radius and enabling line contact between the two, even large-diameter workpieces can be cut quickly and easily by generating a large cutting force when cutting the center part. The present invention is extremely useful industrially because a compact, lightweight, powerful and economical air nipper is obtained, and the spherical projection at the rear end of the nipper is easily finished.

According to a fourth aspect of the present invention, in the first or second aspect, the rectangular cross sections formed at both rear ends of the pair of X-shaped nippers and the inner surface of the central concave hole of the piston are provided. With a rectangular cross-section groove that is engraved from the front end opening to the closed rear end along the axial plane and the rectangular cross section of the rear end of the nipper loosens, even in the case of a large-diameter cut material, A small, lightweight, powerful and economical air nipper that can be cut quickly and easily by generating a large cutting force at the time of cutting is obtained, and the rear end of the nipper has a rectangular cross section of the piston with a large contact area. The invention is of great industrial benefit because of the advantages of being guided and supported along the groove.

[Brief description of the drawings]

FIG. 1 is an overall vertical sectional view showing a two-stage conical-bore piston type air nipper according to a first embodiment of the present invention.

FIG. 2 is an overall longitudinal sectional view showing a parabolic bus-line rotating surface type concave-hole piston type air nipper according to a second embodiment of the present invention.

FIG. 3 is a vector diagram showing components of an axial force W acting on a contact point of a part III in FIG. 2 and reaction forces W ₁ and W ₂ thereof.

FIG. 4 is a longitudinal sectional view and a transverse sectional view showing a central concave hole of a piston according to a third embodiment of the present invention.

FIG. 5 is a longitudinal sectional view and a transverse sectional view showing a central concave hole of a piston according to a fourth embodiment of the present invention.

FIG. 6 is an overall vertical sectional view showing a conventional air nipper.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Holder main body 2a, 2b, 2c Piston 3 End plate 4 Air chamber 5 Vent hole 7 Female thread 8 Male screw 9 O ring 10 O ring 11 Nipper 12 Pattern 13 Pattern 14 Hemisphere part 15 Hemisphere part 16 Cutting blade 17 Cutting blade 18 Support point cross-pin 19 the length of the spring 20 the spring 21 big front tapered conical inner surface (front conical inner surface) 22 rear small tapered conical inner surface (rear conical inner surface) 23 length of the rectangular cross-section groove L ₁ cutting unit L ₂ shank θ Conical angle (twice the generatrix angle) W Axial force

Claims (4)

[Claims] 1. A pair of nippers having a central portion pivotally supported by a fulcrum pin at a front end of a cylindrical holder having a rear end closed, a front portion having a cutting blade, and a rear portion forming a handle, are pivotally supported in an X-shape. At the front end of the piston inserted into the rear part of the holder, a central concave hole having a conical inner surface whose diameter is reduced toward the rear end is recessed, and the rear end of the pair of nippers is made larger in the conical inner surface of the piston. The piston is closed against the spring by introducing compressed air from the rear end of the holder and moving the piston forward against the spring to close the pair of nippers against the spring. , The piston and the nipper are returned to the open position by springs respectively by releasing the compressed air inside the holder. The piston has a front large inner tapered cone and a rear small tapered inner cone. Consisting of An air nipper, characterized in that a coaxial two-stage conical inner surface, which is a rotational surface of a fold line generatrix, is formed as a two-stage conical inner surface by recessing. 2. A modified conical shape according to claim 1, wherein the inner surface of the two-stage cone formed by the fold line of the piston is formed by a rotation surface having a quadratic curve extending smoothly along the fold line as a base line. An air nipper characterized by an inner surface. 3. The piston according to claim 1, wherein a radius of a radius shorter than a radius of a center concave hole of the piston which abuts on a tip of a cross section of both rear ends of the pair of X-shaped nippers is provided. An air nipper, characterized in that both can be in line contact with each other. 4. A pair of X-shaped nippers according to claim 1, wherein said pair of X-shaped nippers have rectangular cross sections formed at both rear ends thereof, and a front end opening along an axial plane in an inner surface of a central concave hole of said piston. And a concave groove having a rectangular cross section which is engraved from the rear end of the nipper to a rectangular cross section of the rear end of the nipper.