JPS6033637B2 - electric hammer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric hammer, and more particularly, to an electric hammer that suppresses vibration.

FIG. 1 shows the structure of a conventional single-cylinder reciprocating electric hammer. A motor 2 is built into the electric hammer body 1, and the rotation of this motor 2 is controlled by a gear 4 fixed to a crankshaft 3. is transmitted to the crank pin 5 via the arrow, and the crank pin 5 rotates in the direction of the arrow.

This rotation of the crank pin 5 is transmitted to a piston 8 attached to a cone rod 6 via a piston pin 7, and the piston 8 reciprocates within a cylinder case 9. A striker 10 is interposed between the piston 8 and the cylinder case 9, and when the piston 8 moves in the direction of the arrow, the air between the striker 10 and the piston 8 is compressed, thereby pushing the striker 10. and hit the end face of bull point 11. The bull point 11 hits, for example, concrete 12, breaks the concrete 12, and then rebounds. Reference numeral 13 indicates a handle for supporting the electric hammer main body 1.

On the other hand, the striker 10 returns to its original position with the rebound from the end face of the bull point 11 and the suction caused by the return stroke of the piston 8, and the same movement is repeated thereafter.

FIG. 2 shows a conventional example of reducing the vibration of the handle of the electric hammer shown in FIG. 1, and the same reference numerals as in FIG. 1 indicate the same parts.

The secondary electric hammers shown in Figure 2 can be roughly divided into i.
As shown in Figures a, b, and c, a cushioning material such as a leaf spring 14, a coil spring 15, or a vibration isolating rubber 16 is interposed between the electric hammer body 1 and the handle 13.

ii An electric hammer main body 1 and a handle 13 are connected via a link mechanism 17 as shown in FIG. 2d.

iii As shown in FIGS. 2e and 2f, there is an electric hammer main body 1 and a handle 13 connected by a link mechanism 17 and a spring 18.

Generally, the conditions that the handle 13 of an electric hammer should meet include the following.

{a- The force applied by the operator to the handle 13 must be sufficiently transmitted to the tip of the bull point 11.

In other words, the handle 13 should not wobble during operation and the force of the hand cannot be sufficiently transmitted.

[b} The wire connecting the electric hammer body and the handle 13 must be flexible in all directions.

In other words, if it is rigid even in one direction, and if there is a direction, vibrations will be more likely to be transmitted from that direction. {c} Keep the weight as light as possible.

The electric hammer itself can be used not only to crush floors, but also ceilings and walls. In cases like this, the electric hammer is lifted by hand, which reduces the strain on the muscles. Applying the above conditions to the conventional electric hammer shown in Figure 2, the coil spring method shown in Figure 2a has a lower spring constant in the vertical direction (30% or less) than that in the horizontal direction. Due to lack of directional rigidity, it tends to wobble sideways, making it difficult to operate.

That is, the axial spring constant ks and the axial spring constant ksR of the coil spring are given by the following equations.

kS: Magazine ·...Publication In the formula above, n: Effective number of turns of the coil spring d: Wire diameter of the coil spring D: Coil diameter G: Modulus of transverse elasticity E: Modulus of longitudinal elasticity H: Effective installation length of the spring Normally E=2. 5, the relationship between ks and RsR is ksR=
0.39ks/{10.76(H/D)2).・・・
．． ... is '3', and the spring constant in the direction perpendicular to the axis is lower than that in the axial direction.

Next, in the leaf spring system shown in FIG. 2b, contrary to the coil spring system described above, the rigidity in the direction perpendicular to the sea bream is too high (several times more) than in the axial direction, making it easier for vibrations to be transmitted from the lateral direction.

Next, the case of the protective rubber method shown in FIG. 2c will be explained.

In general road post-shaped vibration isolating rubber, the spring constant kR in the direction of the mari and the spring constant kRR in the direction perpendicular to the mari are kR=EapA/h (
compression direction) ...(4) kRR=GapAL/h
(Nada section direction) ・・・・・・【51.

In the above formula, AL: Pressure-receiving area of the anti-vibration rubber b: Rubber thickness Eap: Apparent modulus of longitudinal elasticity Gap: Apparent modulus of transverse elasticity Eap and Gap in the above formula are determined by the shape ratio S, and in the case of a cylinder, Eap = (3 14.93$2) G G Gap=114'fly2'd2 In the case of a square column, Eap=(316.58 female 2)G G Gap=・11/3. h2/a2 Shape ratio S is for a cylinder S = d / for an antennal pillar S = ad / 2 (a + d) h for a square pillar S = a / small Therefore, the relationship between kR and kRR is for a cylinder 1 1 kRR=(34.93$2).

F firewood cost lkR... (9} In the case of a square column 1 1 kRR = (36.58 eaves 2) -▽▽box take - kR...
...{l■'9}, since the denominator of both rigid equations is larger, the spring constant in the axial direction (compression direction) is larger than the spring constant in the axis-perpendicular direction (in the rupture direction).

When using anti-vibration rubber as a bush type, the spring constant in all axial directions is: kR: 1. Snake ap〆/soog,.

(r2/r,)Gap/G={1 ten words (three words) 2}-
・Mari right angle direction: kRR= 1.7 (Eap+G)〆/So.

g(r2/r.)Eap/G=43.29 eaves 20.4
34 S; Sancho. So.

g glue 2'r, ) (11), (12), then:
Bush length r: Bush inner diameter r2: Push outer diameter kR and kRR are as follows: kRR = (2.0 x 1.64 $2) kR...
...(13), and in this case, the spring constant in the vertical direction (compression direction) is larger than the spring constant in the axial direction (in the cross-section direction).

In this way, in the case of anti-vibration rubber, if the cutting direction is oriented in the axial direction, the spring constant in the direction perpendicular to the axis will be high, and vibrations from the side will be easily transmitted.

On the other hand, if the compression direction is in the wisterial direction, the spring constant in the angular direction will become too low, and the handle will fluctuate, resulting in poor operability.On the other hand, as shown in Figure 2 a to f, For those equipped with a mechanism, the force applied by the operator is applied to the pull point, making it difficult to operate.

Furthermore, since it is difficult to reduce the rigidity in the lateral direction, vibrations from the lateral direction are easily transmitted. Furthermore, link mechanisms have drawbacks such as being complicated in structure, large in size, and heavy in weight. The purpose of the present invention is to improve the above-mentioned drawbacks and provide an electric hammer that can sufficiently transmit the force applied by the operator to the tip of the bull point and prevent vibrations from being transmitted to the handle from any direction. That is.

The present invention is characterized by an electric hammer body that crushes concrete by striking the hammer with a striker force pushed out by air pressure compressed by the reciprocating motion of a piston. The handle is connected to the handle via a coil spring and anti-vibration rubber, and when the coil spring and anti-vibration rubber are combined, the spring constant is made almost equal in all directions.

An embodiment of the electric hammer main body of the present invention will be described below with reference to FIG.

In FIG. 3, parts with the same reference numerals as in FIG. The vibration isolating rubber 2 is connected in parallel with the axial direction of the coil spring 19.
0 is interposed in the depth direction. Therefore, the vibration isolating rubber 20 is attached in the direction perpendicular to the axis of the coil spring 19 in the compression direction. Of the composite spring constants at this time, the axial spring constant K is the sum of equation {1' and equation '4-,
K=ks+kRR...(14) On the other hand,
The axis-perpendicular spring constant KR is the sum of formula {2) and formula [5), KR=ksR0kR...(
15).

The horizontal spring constant K and the axis-perpendicular spring constant KR can be made to be approximately the same as follows.

(i} First, determine the spring constant K for the desired direction of the ball.

{ii) Set the coil's imitation so that ks+ksR=K. The shape ratio S of the anti-vibration rubber 20 is determined so that stiffness k3:ksR=kR:kRR.

{N} The dimensions and hardness of the vibration isolating rubber 20 are determined so that kR=ks.

FIG. 4 shows another embodiment of the present invention, in which a bush-shaped vibration isolating rubber 21 is used instead of the straight pillar-shaped vibration isolating rubber and is combined with a coil spring 19 in the same manner as described above. be effective.

According to the present invention, the spring constant of the combination of the coil spring and vibration isolating rubber interposed between the electric hammer body and the handle is made almost the same in all directions, so that Vibration can be transmitted and increased, and since there is no weak direction, there is no fluctuation in the handle and the handle is easy to operate.

Furthermore, since the connecting portion is made up of a coil spring and vibration-proof rubber, the overall weight of the electric hammer is also light.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional front view of an electric hammer, FIGS. 2 a to f are schematic diagrams of a conventional electric hammer, and FIG. 3 is a sectional view of essential parts of an embodiment of the electric hammer of the present invention. FIG. 4 is a sectional view of a main part of another embodiment of the electric hammer of the present invention. 1... Electric hammer body, 13'... Handle, 19... Coil spring, 20... Anti-vibration rubber. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. In an electric hammer that crushes concrete, etc. by striking the hammer with a striker that is pushed out by air pressure compressed by the reciprocating motion of a piston, the electric hammer body and the handle that supports the electric hammer body are connected with a coil spring. An electric hammer characterized in that the coil spring and the vibration isolating rubber are connected via a vibration rubber, and the spring constant of the combination of the coil spring and the vibration isolating rubber is made almost equal in all directions.