Leningrad Conference on Drilling and Blasting Technology

V. F. Gorbunov and I. G. Basov

(Presented by Prof. P. M. Alabuzhev, Doctor of Technical Sciences)

In July 1955, Glavuglemash, the management of the Pneumatika plant of the Ministry of Coal Industry, and the Leningrad Regional Mining Scientific and Engineering Society organized a scientific and technical conference for the purpose of summarizing experience in the operation of drilling hammers, identifying current requirements for them, and summarizing theoretical achievements for the creation of higher-productivity drilling machines. The conference was held at the Leningrad Mining Institute, with the participation of representatives of 60 organizations of the ministries of the coal industry, nonferrous and ferrous metallurgy, higher education, transportation routes, and a number of construction ministries engaged in the manufacture or operation of drilling equipment.

The importance of the task considered by the conference was emphasized in his opening address by Comrade Koshevoi B. Kh., deputy chief engineer of Glavuglemash. He expressed confidence that the conference would serve to improve the connection between the scientific forces of institutes and the plants manufacturing drilling machines and the enterprises operating these machines.

The conference heard and discussed a number of reports on the following questions:

1. The theory of the working process and the calculation of pneumatic drilling hammers.
2. The state of production of pneumatic drilling hammers and the tools for them.
3. The operation of drilling hammers.
4. The newest directions in the development of drilling technology in the USSR and abroad.

In the reports of representatives of the Tomsk Polytechnic Institute, the Giproshakhtstroimash Institute, the Pneumatika plant, and others, it was noted that recently a number of studies have been carried out aimed at refining the calculation of drilling hammers and improving existing designs.

But these results still do not fully satisfy the needs of design engineers; therefore, in practice the basic path of designing a new drilling machine “from the rock to the machine,” which can yield the most satisfactory results, is often violated. This is connected with the insufficiently developed theory of rock destruction and drilling tools.

Plants manufacturing drilling hammers are carrying out extensive work to improve the designs of drilling hammers jointly with scientific institutions and industrial enterprises that operate drilling hammers.

In the reports of S. B. Zelenẹtskii, chief engineer of the Pneumatika plant, and V. D. Chugunov, chief designer of the Kyshtym Mechanical Plant,

Chief designer of the Kommunist plant G. M. Koloberdin and others noted the achievements of factories in manufacturing new types of machines. The work of designers at the Pneumatika plant and the Kyshtym Mechanical Plant in creating drilling hammers with dust collection, side flushing, and independent rotation of the drill deserves special attention.

The V. M. Molotov Plant has achieved good quality indicators. The PM-508 hammer of this plant, in terms of manufacturing quality and performance, is not inferior to the best foreign models of hammers of this class. The Krivoi Rog Kommunist plant maintains close ties with the mechanizers of the Krivoi Rog iron-ore basin, Donbass, and also with the scientific personnel of the West Siberian Branch of the USSR Academy of Sciences and the Tomsk Polytechnic Institute; the Pneumatika plant cooperates with the staff of the Giprouglemash Institute, TPI, and others. However, this connection is still insufficient.

At the conference it was noted that the plants’ work on creating their own experimental base was weak, and because of this the plants cannot test their machines fully enough.

The Pneumatika plant does not pay sufficient attention to the quality of the drilling hammers it produces, as a result of which the OM-506 hammers are considered the worst in quality among domestic hammers of this class.

The insufficient development of the theory of operation of the rotary devices of drilling hammers and the problem of using high-pressure compressed air were also noted.

In the reports by G. M. Koloberdin, V. D. Chugunov, and others, it was especially noted that specialization must be introduced for plants in the manufacture of individual types of drilling hammers, the selection of which for series production should be made on the basis of broad interdepartmental comparative tests of all types of domestic and foreign drilling hammers.

The positive achievements of the Kharkov branch of Soyuztverdosplav (speaker V. N. Bakul), the VNIIOmshS and Giprouglemash institutes (speakers I. E. Detistov and Slesarev) in creating high-quality drilling tools for drilling machines were noted.

In his report, V. N. Bakul recommended expanding the number of grades of hard alloy used for making drill bits and proposed changing the shape of the hard-alloy plates, and, in connection with this, the geometry of the drill bits, by using cylindrical inserts (bits with discontinuous cutting edges). Similar work on creating new forms of tools was also covered in the report by Comrade Slesarev (Giprouglemash) and by other speakers. The conference noted the weak connection among research organizations themselves and with the design departments of industrial enterprises, as a result of which the tools that have been developed are not introduced into production.

Serious attention at the conference was devoted to the question of operating drilling hammers.

In the speeches of V. Kh. Koshevoi and A. Bondarenko, the low level of culture among mechanizers in servicing machines and the careless handling of existing equipment were noted, as a result of which the service life of drilling hammers is shortened and, when mine shafts are being sunk, sometimes reaches only 1–2 months instead of the six months provided for by the plants.

It is known from foreign practice that the service life of a drilling hammer can be brought up to 3 years through good maintenance, properly selected lubricants, and a lubrication system. This was also emphasized in his speech by a representative of the Uralvzryvprom trust, Comrade Chulkov, who reported that, with good maintenance, their drilling hammers operate for 2.5–3 years when converted to single-shift operation.

The good practice of organizing warranty repairs at the Kizel Ore-Repair Plant and the Krivoi Rog Kommunist plant was noted,

that make it possible to monitor the wear of individual parts of drilling hammers and to take timely measures preventing failure of the drilling hammer during operation. Proper lubrication of the drilling machine contributes to reliable operation (report by S. I. Dobroborskii), increasing its service life and productivity. The conference noted the unsatisfactory state of the theoretical substantiation of rational lubrication systems, the best lubricating materials, and the development of automatic oilers for drilling hammers. Nor has the question been resolved of whether it is advisable to use side flushing instead of axial flushing, since it reduces the productivity of the drilling hammer.

The conference was informed about experience in the operation of drilling hammers abroad by senior research associate of VUGI A. I. Medvedko, head of the department of the institute “Giproshakhtostroimash” M. E. Lesik, and chief engineer of the “Pnevmatika” plant S. B. Zelenetskii. They noted a certain lag in our drilling technology in the creation of high-frequency hammers (with a number of blows of 2500–5000 blows/min), the use of drill carriages with manipulators for 3–6 drilling hammers with automatic feeds, and the introduction into production of light drilling hammers with pneumatic supports.

In A. I. Medvedko’s report, special emphasis was placed on the need to conduct broad research and to introduce into production more progressive drilling methods using thermodynamic, ultrasonic effects, etc.

As a result of discussion of the reports on the above-mentioned and certain other related questions, the conference adopted a resolution providing for further expansion of cooperation among various enterprises and institutions working on the improvement of drilling technology, strengthening mutual information about the work being carried out, increasing the pace of design and introduction into production of new high-performance drilling machines, and other measures.

Among the tasks set by the conference for our science and technology are:

1. To generalize theoretical achievements in the field of pneumatic drilling machines in order to create, on this basis, a theory for calculating new machines.

2. To create a unified methodology for the study (testing) of existing drilling machines.

3. To develop a theory of the drilling tool by generalizing the data of advanced experience.

4. To create new high-performance drilling hammers: a) light ones with a number of blows from 3000 to 5000 per minute and with automatic feed; b) column-mounted ones weighing up to 80 kg with automatic feeds.

5. To create units for group drilling of the face of horizontal and vertical development workings.

6. To wage an active struggle to improve the working conditions of drillers by creating and expanding the use of noise suppressors, dust collectors, etc.

7. To continue further development of designs for electric drilling hammers.

8. To expand information on the implementation of these problems by various organizations, and to strengthen the interconnection among industrial enterprises, plants manufacturing drilling machines and tools, and scientific workers.