JPS59219177A - Striking chisel mounted to striking device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a percussion chisel to be attached to a percussion device, and more particularly to a percussion chisel for crushing concrete, rock, or paved road surfaces (so-called breaker).
), it is possible to optimize the mass ratio relationship with respect to the hammer unit in the striking device, and as a result,
This invention relates to a percussion chisel that can strengthen the crushing force of a percussion device and extend the life of the percussion chisel itself.

This type of striking device introduces compressed air generated by a compressed air generator, such as those often seen at road construction sites, into the striking device main body via a bowse, and uses the expansion force of this compressed air to piston the piston. In addition to the configuration in which the hammer is moved up and down to continuously strike the striking chisel attached to the tip of the device, there is also a structure in which the hammer is moved up and down to continuously strike the striking chisel attached to the tip of the device. There are portable striking devices that can obtain
(See No. 7).

In order to understand the significance of the present invention and its unique effects, it is necessary to understand the structure and operation of such a percussion device.Next, an example of the above portable percussion device will be explained based on FIG. explain.

An outer cylinder 2 is formed inside the cylindrical main body 1, and a movable solinder 3 is fitted into the upper cylinder so that it can reciprocate. This rJJ moving cylinder 3 and the free screw 1-4 fitted inside it constitute a so-called striking mechanism A.

Here, the striking mechanism is composed of a driving body I3 that reciprocates, and a driven body C that follows this driving body B through an elastic body such as air, and the driven body C is delayed due to inertia. By accelerating the driven body C using the elastic force of the elastic body such as air generated by the movement, and thereby hitting the target to be hit at a much higher speed than the reciprocating speed of the driving body B. , to obtain the desired impact energy key. As the elastic body, air can be used as in this example, or coil springs can also be used.

In this example, the μ'' cylinder 3 is used as a driving body B driven via a crank mechanism 5, and the free piston 4 is used as a driven body. In addition, on the contrary, a screw-shaped driving body is connected to a crank mechanism, a cylindrical driven body is fitted onto this driving body, and the air trapped between them functions as an elastic body. You can also do that.

A striking rod 6 is protruded from the lower part of the free piston 4, and when the free piston 4 moves downward at high speed following the movement of the uJ moving cylinder 3, this striking rod 6 engages the movable cylinder 3.
It protrudes downward from a through hole 7 made in the lower part of the chisel 8 and strikes the top of the striking chisel 8.

In addition, in this example, a mantle 9 is provided on the outside of the outer cylinder 2 to form a double cylinder, and ventilation holes 10 and 11 are provided at the top and bottom of the outer cylinder 2, so that the inside of the outer cylinder 2 is Movable cylinder
A portion above iiJ ridge cylinder 3 and a portion below iiJ ridge cylinder 3 are communicated with each other to reduce resistance to the downward movement of iiJ moving cylinder 3.

The interior of the movable cylinder 3 is divided into an upper pneumatic chamber 12 and a pneumatic chamber 13 by the free piston 4. These air pressure chambers 12, 13 are alternately compressed by the inertia delay of the free piston 1-4, and the resulting air elastic force accelerates the 70 reciprocating movement of the free piston 4. In this example, an appropriate number of through holes 14 are provided in the side wall of the movable cylinder 3, and when the free piston 4 moves downward, the upper air pressure chamber 12 is communicated with the outside air, so that the upper air pressure chamber 12 can be evacuated. By preventing the free piston 4 from interfering with its acceleration during the downward movement and by communicating the upper air pressure chamber 13 with the outside air when the free piston 4 moves upward, the air pressure chambers 1; This prevents vacuum pressure from interfering with the upward movement of the free piston 4.

At the bottom of the main body 1, a striking chisel 8, which is struck by the striking mechanism, is installed, and in this example,
It is structured as follows.

This outer cylinder 2 is located at the bottom of the outer cylinder 2.
A boss portion 15 of a predetermined length is formed to communicate between the inside and the outside, and this boss portion 15 supports the upper shaft portion of the striking chisel 8 so as to be able to slide vertically and reciprocally. The striking 1-1 chisel 8 is supported so as to have the same axis as the movable cylinder 3 or the free piston 4, and its top protrudes slightly into the outer cylinder 2. This boss part 15
The outer diameter of the portion below the upper end is slightly smaller than the inner diameter of the cylindrical holder 16 that extends downward from the lower outer circumference of the outer cylinder 2. In the cylindrical space 17 formed,
Insert a compression coil spring 18, which is a compression elastic body,
The lower end of the compression coil spring 18 is engaged with the upper step of a large diameter portion 19 formed at the middle portion of the striking chisel 8 via a collar 20 or the like. As a result, the striking diesel 8 is then elastically biased downward.

The lower end of the striking chisel 8 projects outward from a through hole 21 formed in the bottom of a cylindrical boulder 16 extending from the lower outer periphery of the outer cylinder 2. The diameter of this through hole 21 is made larger than the shaft diameter of the striking diesel 8 and smaller than the large diameter portion 19, so that it functions as a stopper to prevent the striking diesel 8 from being pulled out. It is.

In the above striking device A, driving the crank mechanism 5,
When the movable cylinder 3 is reciprocated up and down, the free piston 4 fitted inside the movable cylinder 3 causes alternating compression bursts of the upper air pressure chamber 12 and the -1 air pressure chamber 13. Its descending speed is accelerated to a much higher speed than the descending speed of the movable cylinder 3, and it collides with the top of the striking chisel 8 with large kinetic energy.

The striking chisel 8 given impact kinetic energy by the free piston 4 should destroy the object to be struck with its impact force.

However, when an attempt is made to actually crush a hard object such as concrete using the above-mentioned percussion device, the tip of the percussion chisel 8 becomes extremely hot, and in severe cases, The tip of this chisel sometimes melted due to heat. Although this fact has been known among workers for a long time, the cause has not been investigated in depth, and countermeasures such as changing the abrasiveness of the tip of the chisel to cemented carbide, for example, have been proposed. Stay in the saw. However, when hitting a hard object, as mentioned above, heat is generated that can even melt steel, so no matter how hard the tip of the chisel is, as long as it is made of steel, it is fundamentally It is not a solution.

As a result of detailed observation of the behavior between the percussion chisel and the object to be struck during the use of the percussion device, the inventor found that heat generation at the tip of the chisel as described in section 2 is due to the intense reciprocating motion of the chisel. It was discovered that the cause was the sliding friction that occurred between the tip of the chisel and the striking object. In the conventional striking device, such a reciprocating motion of the chisel is caused by the W@ of the hammer (free piston in the above example) that strikes the mass of the chisel.
I discovered that this occurs because it is relatively small.

Conventionally, the influence of the relationship between the mass of the chisel and the mass of the hammer that strikes it on the crushing force has not been considered, even if the mass of the hammer is smaller than that of the chisel. This was because there was a vague mechanical common sense in the industry that if you increased the speed of the hammer, you could increase the kinetic energy of the hammer, and therefore the crushing force of the chisel could be amplified. It is believed that there is.

U: Even if the mass of the hammer is smaller than that of the striking chisel, if the speed of the hammer is increased, the chisel collided with it will have a large kinetic energy corresponding to the increased speed of the hammer. is given. However,
In this case, a large portion of the kinetic energy of the hammer before the collision is converted into the energy of the rebound motion of the hammer after the collision, resulting in poor conversion efficiency into chisel motion. Furthermore, in the actual striking action, it is necessary to consider not only the relationship between the hammer and the chisel (but also the relationship between these and the object to be struck).

Now, consider a case where the tip of the chisel 8 hits the object to be struck, as shown in FIG. Hammer unit B f(
I shall be smaller than that of chisel 8. When the hammer E strikes the rear end of the chisel 8 at a speed 11, a certain amount of impact energy is given to the chisel E. Depending on the hardness of the object being struck, part of the energy is The energy is consumed to break the object being hit, and the remaining energy is consumed to bounce back the hammer E.

At the same time, the chisel itself also rebounds from the object being struck. As a result of experiments, it was found that the phenomenon of repulsion of the chisel itself is more pronounced as the weight of the hammer is smaller compared to the mass of the chisel. This is considered to be because the chisel 8 itself can retreat rearward as the hammer unit E is instantly bounced back after colliding with the chisel 19.

” 2, the fact that the chisel 8 itself struck by the hammer unit repulses against the object being struck, means that
When the chisel 8 is continuously struck by the hammer unit E, the chisel 8 violently reciprocates with respect to the hammer tr X=1.

The above-mentioned heat generation phenomenon at the tip of the chisel is caused by the rubbing motion of the chisel as it moves back and forth against the object to be struck.

On the other hand, if the mass of the chisel 8 is approximately equal to or less than that of the hammer integrated IL, the impact acceleration given to the chisel 8 by the collision of the hammer integrated E will be larger than in the above case. Therefore, more energy is consumed in crushing the object to be struck than in the above case, and therefore, the amount of the chisel (chisel) (to be struck) entering into the inside of the object to be struck (1) increases.

In this case, the crushed and collapsed object to be struck exerts a cushioning effect, and the chisel 8 hardly ever rebounds against it. Therefore, even if the chisel 8 is hit continuously, the chisel 8 will not make violent reciprocating movements.
There is no longer any possibility of high temperatures being generated due to frictional heat.

In this way, the chisel 8 in the striking device hits the object 1 to be struck.
), but it does not depend on the speed of the hammer unit E or the hardness of the tip of the chisel 8, but rather how effectively the kinetic energy of the hammer unit E can be used to crush the impact acceleration motion of the chisel 8. or can be converted to
It depends on

If the mass of the chisel 8 is made larger than the mass of the hammer unit E as in the past, no matter how fast the hammer unit E increases, most of its kinetic energy will be lost to the rebound movement of the hammer unit E after striking or the chisel. The portion that is converted into the repulsion movement of the chisel 8, etc., and the portion that is converted into the 1ti impact acceleration movement in the driving direction of the chisel 8 becomes extremely small. As a result, as mentioned above, not only does the crushing force of the chisel tip decrease, but the chisel itself repulses due to the decrease in crushing force, and this causes frictional heat, resulting in an extremely shortened chisel life. Become.

As a result of the inventor's experimental observations, in order for the chisel to effectively crush and hang the object to be hit, the mass of the chisel must be at most about 1 of the mass of the hammer.

It has been found that it is preferable to keep it at 1 times or less.

On the other hand, it is not possible to increase the crushing force by simply reducing the mass of the chisel and its outer diameter.

In other words, by reducing the outer diameter of the chisel, it is possible to make it easier for dirt to penetrate into the target object, but especially when hitting an object with viscoelasticity such as asphalt, it is difficult to penetrate the target object. Due to the wedge effect, the baby will not become pregnant until it breaks. As described above, the chisel attached to the striking device needs to have an outer diameter of a certain value or more. In the past, the influence of the relationship between the mass of the chisel and the hammer as a whole on the crushing force of the chisel was not considered, because as mentioned above, the chisel needs to have an outer diameter above a certain level. This is probably because reducing the weight of a chisel was thought to be outside the scope of common sense due to the need to obtain strength from the chisel.

As a result of the experimental observation described above, the present invention is based on the results of the above-mentioned experimental observations. In other words, in order to extend the life of the chisel, it is necessary to eliminate the violent reciprocating movement of the chisel that occurs during striking, thereby generating frictional heat between it and the object to be struck. In order to eliminate the repulsive reciprocating motion of the chisel as described above, it is sufficient to make the mass of the chisel approximately equal to or greater than the mass of the hammer. This was based on the consideration that in order to maintain the crushing power of the chisel, it was necessary to increase the outer diameter to some extent, and the purpose was to reduce the weight of the chisel without shortening the outer diameter. +-1 equipment is to provide a river striking chisel.

In order to achieve this objective, the present invention takes the following technical measures.

That is, a hollow part is provided inside the striking chisel.

This makes it possible to reduce the overall weight of the percussion chisel by a considerable amount while maintaining the same outer diameter as conventional chisels. As a result, it is possible to make the weight of the chisel approximately equal to or less than the weight of the hammer, which eliminates the phenomenon that conventionally occurs when striking, that is, the reciprocating movement of the chisel against the object to be struck, and this It is possible to minimize the generation of frictional heat between the hammer and the target object due to the impact, and to significantly extend the life of the chisel by 1ft1. Since it can be converted into j-impact acceleration motion, the crushing force of the chisel can be significantly increased compared to conventional methods. Moreover, since the outer diameter of the chisel has not been reduced due to weight reduction, the function of splitting the object to be crushed by a wedge effect is not impaired.

Embodiments of the present invention will be specifically described below with reference to the drawings.

1' i! of the striking chisel 8a according to the present embodiment. i
The shape is similar to the shape of the top of the conventional percussion chisel 8 (nearly 4) attached to the percussion device shown in Fig. 1, so that it can be attached as is to the percussion device shown in Fig. 1. In other words, a large diameter portion 19a is formed at a predetermined portion L- at 91% of the axis of the top, and a collar 20 for transmitting the elasticity of the coil spring 18 to the chisel 8a engages with this. I'm starting to do that.

As is clear from the figure, the percussion chisel 11a of this embodiment
In order to form the cavity 22 inside,
The chisel itself 8a is divided into two parts, a proximal end member 23 and a distal end member 24, each of which has a hole 2 having a constant depth in the axial direction.
5 and 26, and these are connected by taber fitting.

That is, the distal end member 24 is provided with an axial hole 26 in which a tapered portion 27 is formed near the entrance, while the distal shaft portion 28 of the proximal end member 23 is provided with the axial hole 26 of the distal end portion 4tA 24. The tapered shaft part 28 is made into a tapered shaft part that can be fitted into the tapered part 27 of the tapered shaft part 28, and an axial hole 25 is also formed in the tapered shaft part 28.
and are connected so that each tapered portion 27 and tapered shaft portion 28 fit together.

In this embodiment, the distal end member 24 and the proximal end member 23
Although the connection is made by tapered fitting, it goes without saying that this may also be done by screw means. Also,
The inner diameter and depth of the axial holes drilled in each of the portions H may be determined as appropriate depending on how much weight the hammer + 1,000 cell 8a is to be reduced in relation to the hammer.

Further, the axial hole 25 provided in the base end member 23 may or may not be provided as necessary.

Furthermore, it is convenient to fill the cavity 22 with a light sound-absorbing material, such as asbestos, since this exhibits a sound-muffling effect.

As described above, the percussion chisel used in the percussion device according to the present invention can reduce its weight without reducing its external size. 1 jl can be optimized, it is also possible to strengthen the crushing force of the percussion device and extend the life of the chisel.The percussion chisel of the present invention can be In addition to a striking device that includes a striking mechanism consisting of a movable cylinder and a free piston fitted into the movable cylinder, the hammer unit also uses the expansion force of compressed air generated by a compressed air generator. Of course, it can also be used as a percussion chisel for a percussion device configured to reciprocate and thereby percussion.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an example of a percussion device for attaching a percussion chisel according to the present invention, FIG. 2 is an experimental overview diagram for explaining the present invention in detail, and FIG. It is a sectional view showing an example. 8a...Striking chisel, 22...Cavity, Applicant Yamada Heavy Industries Co., Ltd. Agent Patent attorney Higuchi Climbing 2 people 43

Claims (1)

[Claims] (1) A striking chisel, which is one example of a striking device, is characterized by having a cavity inside.