SU815276A2 - Pneumatic hammer - Google Patents

Description

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The invention relates to rock and construction materials of impact action and can be used to create hand-held pneumatic hammers with valveless air distribution, as well as heavy air-impact machines.

According to the main author. St. No. 658268 is known for a pneumatic hammer with valveless air distribution, comprising a housing with a central stepped channel in which a stepped impactor with a stepped channel is installed with the possibility of reciprocating axial movement, forming an idling chamber with the walls of the working stroke KciMepy, constantly communicating during operation with a compressed air source, an atmospheric pressure chamber and an accumulation chamber, air supply and exhaust ducts, a handle and a working tool. In the wall of the housing separating the accumulation chamber and the idling chamber, throttle channels are made to permanently communicate these chambers with each other.

Known hammer has high performance

in particular, relatively low specific consumption of compressed air and increased energy of a single strike 1.

 However, when the hammer is operated, there is significant exhaust air exhaust noise and, moreover, due to the rotation of the flow in the stepped channel of the impactor, the hydraulic losses in the latter are increased, which reduces the energy of a single blow and efficiency, i.e. causes incomplete use of the energy of compressed air and impairs the filling of the chamber E j of the working stroke with energy carrier.

The purpose of the invention is to increase the energy of a single blow of a pneumatic hammer, as well as to reduce the noise level during operation and to increase the overall efficiency.

The goal is achieved by the fact that in a pneumatic hammer the outputs of the channel of a stepped striker on the side surface of its lower stage and on the end surface of the larger stage have an ellipse shape.

The elongated elliptical orifice of the inclined channel of the impactor increases the communication time between the working chamber and the network pressure chambers.

and battery; the as a result, the filling time of the chamber with compressed air increases, the average air pressure in this chamber increases as the impactor moves to the tool, and hence the energy of a single impact.

The oblique slice of the sloping channel of the impactor causes the exhaust noise level to decrease by 3-4 decibels, both in the low-frequency and high-frequency parts of the spectrum, due to the smooth increase and decrease of the exhaust pressure and a decrease in its peak value.

An extended oblique slice of the inclined channel of the impactor, smoothly causes a change in the area of the hole when the compressed air is admitted and exhaust, which significantly improves the vibration and force characteristics of the hammer.

The presence of a straight channel in the impactor reduces the hydraulic losses in the not (there is no rotation of the air flow in the channel), which allows more complete use of the energy of compressed air, i.e. increase the efficiency of the hammer.

With other things being equal, the reclining channel causes a much lower stress concentration in the impactor and weakens its cross sections, i.e. causes greater durability of the hammer.

The drawing shows a pneumatic hammer.

The hammer includes a housing 1 in which a stepped impactor 2 with an inclined channel 3 is installed with reciprocating axial movement with a possibility of reciprocating axial movement, a handle 4 with a starting device (not shown) and working tool 5 with device b for holding it. Case 1, except for the central one, has air inlet 7 and exhaust 8 channels, which are closed by a split ring 9.

Channel 3 of the stepped impactor 2 is inclined to the geometric axis of the latter by an angle of 10–15 and has an exit 10 in the form of an ellipse on the front surface 11 of its larger step and in the form of an ellipse (oblique cut) 12 - on the lateral surface of the smaller step of the impactor 2. At In this case, the major axis of the elliptical orifice of the oblique 12 is 5.76-3.86 times greater than the diameter of channel 3 and parallel to the geometrical axis of the impactor 2.

The drummer 2 forms with the walls of the casing 1 a working stroke chamber 13, an idle annular chamber 14 continuously communicated when operating with a source of compressed air, an atmospheric pressure chamber 15 and an accumulation chamber 16,

In the wall 17 of the housing 1, which separates the storage chamber 16 and the idling chamber 14, are made

Throttle channels 18, which constantly communicate with each other.

The accumulation chamber 16 and the idling chamber 14 through the channel 3 of the striker 2 periodically communicate with the camera 13 of the working stroke. The latter, via the same channel 3, also periodically communicates with the chamber 15. The chamber 15, via the exhaust ducts 8, is constantly in communication with the atmosphere, and the chambers 14 and 16 s. the atmosphere is constantly disconnected. When the launcher is on, the chamber 14 is constantly communicated via channels 7 with the compressed air network.

The drawing also indicates the annular end 19 of the striker 2 and the wall 20 of the housing 1.

Pneumatic hammer works as follows.

After turning on the starter, handle 4, the compressed air enters through canal 7 into chamber 14 of idling. The pressure of compressed air at the annular end 19 of the firing pin 2 from the side of the chamber 14 causes the movement of the firing pin 2 from the tool 5. The idling will begin. At the beginning of idling, the impactor 2 does not experience any back pressure from the side of chamber 13, since at that time it is in communication with the atmosphere through channel 3 of impactor 2, chamber 15 and exhaust channels 8.

From the moment the starter is turned on, the mains air from Ks1mera 14 through the throttle channels 18 begins to flow into the accumulation chamber 16, increasing the pressure in it.

- After the elliptical outlet 12 of the duct 3 of the striker 2 of the housing wall 20 closes, the pressure of the air cut off in the chamber 13 begins to increase. increasing the back pressure on the drummer 2..

However, this Jump against the back pressure .-; is not relatively small, since at the time of the message of the accumulation chamber 16 with the camera 13, the volume of the latter is several (3-4) times the volume of the battery cell. Therefore, the marked jump of the resistance of the camera 13 at the beginning of idling does not lead to deterioration of the vibration parameters of the hammer.

With further movement of the drummer 2, the back pressure on it from the side of chamber 13 increases rapidly, n6 smoothly. This is facilitated by the continuous leakage into the chamber 13 of the supply air through the throttles 18, the accumulation chamber 16 and the channel 3 of the striker. Thanks to the significant flow area of the channel 3 drummer

2, the pressures in the chambers 13 and 16 are constantly equalized for almost the entire period of their communication.

As the backpressure chamber 13 increases, the movement of the striker 2 slows down. At some point, the elliptical output 12 of the channel 3 of the striker 2 partially overlaps with the wall 20 of the housing 1, however, the thickness of this wall is less than the length of the elliptical output 12 of the channel 3. Therefore, at the initial moment of communication of the camera 14 with the elliptical output

12, channel 3, the network air from it rushes through channel 3 not. only into chamber 13, but also into accumulator chamber 16, the additional volume of which reduces the spasmodic increase in back pressure in the chamber

13 working stroke, which improves the vibration characteristics of the hammer. Continuing the motion due to inertial forces, the striker 2 at the end of idling divides the chambers 14 and 16 for a short time.

and due to the difference in pressure forces acting on the torei 21 and the annular end 19 of the impactor 2, after stopping, it begins an accelerated motion in the direction of the tool 5, making a working stroke.

Elliptical output 12 of channel 3 again reports KctMepH 14 and 16 for a short time, but the pressure in them during this period is almost the same and close to the network one. The passage of the wall 20 of the housing 1, the elliptical outlet 12 of the channel 3 is completely opened from the side of the accumulation chamber 16, and the air inclined therein, as well as the network air entering through the throttle channels 18, ensures, through channel 3, in the chamber Ij working stroke of higher pressure.

Higher average pressure on the cradle 2 during the working stroke due to the use of a slightly larger amount of air in the working cycle, due to the passage through the elliptical outlet 12 of the channel 3 of compressed air into the chamber 16 from the chamber 14 at the end of the idle and the beginning of the working stroke of the striker 2, and

also due to an increase in the intake time, it provides a proportional increase in the energy of a single blow without an increase in the specific consumption of energy carrier.

In the period preceding the exhaust from the chamber 13, the elliptical outlet 12 of the channel 3 of the striker overlaps with the wall 20 of the housing 1, and the accumulator chamber 16 is disconnected from the chamber 13. Further movement of the striker

0 and provides an opening of the elliptical output 2 of channel 3 from the side of chamber 15. The exhaust from chamber 13 occurs. At the same time, the output 12 3 of the striker 2 is opened in 15

5 at a gradually increasing depth of channel 3. This is a smoother opening of channel 3 in. drummer provides more smooth larastia front pressure front at the exhaust

0 and reduces its peak value, which reduces the noise level in the low-frequency part of the spectrum.

The presence of an elliptical hole (oblique cpeaia) also causes a smooth separation of the jet from the firing pin,

5 i.e. reduces 1 ratio skbrosty expiration of air from the channel 3. The latter reduces the effect of sharp edges reduces the noise level in the high-frequency part of the spectrum.

Q

After exhausting, overcoming the compressed air resistance from the side of the annular chamber 14, 2 strikes the shank of the tool 5, and the cycle repeats.

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Claims (1)

1. USSR author's certificate 50 658268, cl. B 21 C 3/24, 12.22.76.