overhaul of rock drilling rigs

1 Overhaul timing and overhaul confirmation procedures

1.1 Timing of overhaul

The overhaul time of rock drilling rigs is generally after 8 to 10 years of operation, and the rock drilling impact time generally reaches 15,000 to 20,000 hours. The overall technical performance, drilling efficiency and accuracy decrease greatly, and the downtime for maintenance increases. When repairs are no longer sufficient to maintain the technical performance of the equipment, the user can apply for overhaul.

1.2 Overhaul confirmation procedure

The overhaul confirmation process implements a three-level technical appraisal system, that is, preliminary appraisal by the grassroots team, review by the business department, and review by the superior authority. The maintenance team of the grassroots unit will conduct technical appraisal without disassembly, submit an application for overhaul, and submit it to the equipment management department at the same level for review. The equipment management department shall make a horizontal comparison based on the equipment requirements for annual construction tasks, the inventory of equipment of the same type, and the technical status of the equipment to determine whether the equipment is suitable for overhaul, and report it to the superior authority for filing, waiting for the superior authority to issue an annual equipment overhaul plan.

After the equipment repair plan is issued, the equipment management department coordinates professional maintenance personnel to conduct detailed disassembly, clarify repair parts and components, and compile a detailed spare parts demand plan, outsourcing processing plan, and oil-attached auxiliary material plan. Based on the overhaul equipment application plan, the superior authority promptly organizes on-site review by professional forces, studies and determines the repair level and repair method, and finally approves the repair plan.

2. Preparation before repair

2.1 Compilation of technical data

Before repairing equipment, prepare a history of use and repair of the equipment, and collect as much technical information as possible about the model’s operating instructions, parts manuals, repair manuals, and overhaul files for similar equipment over the years. Adequate preparation of technical data is the basis for standardized equipment maintenance and is also the technical legal basis. Referring to the overhaul files of other equipment can enable us to accumulate necessary experience and avoid detours. It is necessary to ask the technical service provider to provide as detailed technical information on the equipment as possible, especially repair standard information. In addition, the internal training materials provided by the manufacturer are also a good reference source for repairs, which can enable us to gain a deeper understanding of the working principle of the equipment or assembly during the disassembly process.

For foreign language repair information on key parts of imported equipment, specialized technical personnel should be organized to translate and sort out the information, and should be repeatedly checked with equipment operators to prevent translation errors. The original text and translation should be numbered and archived and properly kept.

2.2 Plan preparation

A detailed maintenance plan is the basis for a successful equipment overhaul. It must be a complete plan based on equipment disassembly, involving professionals, and technically executable. The overhaul experience over the years proves that without dismantling the equipment, it is unscientific to rely only on the description of the operator, the maintenance experience of the appraiser, and copying the overhaul list of the same type of equipment in previous years. In this way, a secondary appraisal is likely to occur after the equipment is disassembled. The maintenance list needs to be added, deleted, or modified. If the scope of the increase is large, a second spare parts bidding will be required. This not only increases the workload of the agency, but also greatly extends the repair cycle.

The maintenance plan should include: ① Determine the maintenance location and location; ② Define the overhaul management organizational structure and division of responsibilities, and identify the majors and participants; ③ Clarify the repair process and precautions; ④ Attach an appraisal and three certificates approved by the superior Plans: Engineering equipment technical appraisal form and spare parts demand plan, outsourcing maintenance and processing plan, oil-attached auxiliary materials plan.

2.3 Repair site preparation

Rock drilling rigs are relatively complex large-scale equipment, and the maintenance site cannot be too simple. The area of the maintenance site must meet the basic disassembly and assembly needs. Generally, the main workshop is not less than 100m², the space height is not less than 6m, and it is equipped with a truss truck of ≥5t.

In order to ensure work efficiency, in addition to basic tools and equipment, special repair and monitoring tools are also essential. For example, hydraulic ejector specially used to remove pins, complete set of rock drill repair tools, hydraulic test bench, complete set of oil pipe processing equipment, etc. In order to meet the needs of large-area cleaning and paint removal, high-pressure cleaning water guns and pneumatic sandblasting machines with a pressure of ≥20MPa can be configured.

2.4 Training of participants

Rock drilling rig overhaul is a specialized activity, which is different from daily repairs and requires higher technical standards. Participants must undergo systematic training before repairs. The specific training method can coordinate the training of technical service providers, or arrange training for internal key personnel. The purpose of the training is to let everyone understand the basic procedures of repair plans and overhauls, become familiar with various technical materials, master the working principles of equipment, understand their responsibilities and positioning, and prevent the occurrence of buck-passing.

Learning by doing is an effective way to improve yourself in practice. As a trainee, you can gain knowledge from primary sources such as equipment manufacturers, technical service providers and professional books to solve practical maintenance problems encountered. Units can also take advantage of the overhaul opportunity to select operators or repairmen to participate in the overhaul work to integrate training and quickly improve the repair capabilities of front-line personnel so that they can better use equipment and tap the potential of equipment efficiency. In principle, the captain of the aircraft must participate in the overhaul work throughout the entire process.

The training objectives for the participants are as follows: ① Be familiar with and understand the appearance of various mechanical components, hydraulic components, and electrical components installed on the equipment, match them with the system schematic diagram, and solve the problem of “what they are” ; ② You must understand the role of each component in the system and solve the problem of “what it does”; ③ Be clear about the internal structure and working principles of various components, and try to be as familiar as possible to solve the problem of “why”; ④ It is necessary to have a comprehensive understanding of hydraulic circuits, electrical circuits, and water and gas circuits, master the functions and interrelationships of each component in the circuit and system, and solve the “how” problem.

3. Control of key links in repair

3.1 Maintenance and replacement standards of each assembly

Overhaul must take reliability and safety as the main goals. In principle, the replacement of components is determined based on the service life recommended by the equipment manufacturer. Generally, the hydraulic pump must be replaced, and the valve parts must be inspected to determine whether to replace them. It is best to replace all hydraulic hoses in the system, replace all seals, and replace the filter elements of the filters at each location. All monitoring instruments such as pressure gauges and timers must be calibrated or replaced.

The working arm end is the focus of overhaul and must be replaced if it is eligible for replacement. Under normal circumstances, consumable and wearing parts must be replaced, such as the wear-resistant steel skin of the propulsion beam, rubber top plate, propulsion and return wire ropes, etc. The pusher beam must be replaced if it is bent. Even if the pressure monitoring of the hydraulic cylinder is qualified, all seals should be disassembled and replaced. All pins and pin sleeves at the arm end should be replaced, and the base holes of the pins should be inspected and repaired to their original dimensions.

The design life of the engine is generally longer than the life of the vehicle. The engine should be fully inspected and maintained during overhaul to ensure its reliability. The electrical system will be repaired depending on the normal working stability of the equipment, and all cables and main electrical control cabinets will be replaced if necessary. If the air compressor and high-pressure water pump have not been replaced in the early stage and have a history of maintenance, it is recommended to replace them with new ones.

Overhaul must adhere to concept innovation and cannot “repair the old as before”. It is necessary to upgrade the equipment or improve its functions in a timely manner depending on the degree of technological development. For example, the DCS1200 rock drilling control system adopted 20 years ago can be upgraded to the currently commonly used DCS1800 rock drilling control system; the rock drill is the core component of the rock drilling rig, and the COP1838ME rock drill was the standard machine more than ten years ago. model, it can also be upgraded to the more durable COP1838HD or COP1838HD+ rock drill.

For models that can be restored to their original accuracy requirements through maintenance methods, every effort should be made to ensure that they meet the original accuracy standards. For models that cannot be restored to original factory standards, some emphasis should be placed on them. For several indicators that are closely related, such as the stability of the pressure of the entire machine system, the accuracy of the drill arm positioning, the reliability of the electrical system, etc., more technical efforts should be invested to make them meet the minimum technical standards. For the repair of specific parts, a reasonable repair plan should be formulated based on the structural characteristics and accuracy of the workpiece to be repaired and combined with the on-site repair capabilities, and corresponding repair methods should be used for repair.

3.2 Pollution control during maintenance

There is a famous saying in the repair industry: “80% of hydraulic system failures are caused by contamination of hydraulic oil and hydraulic systems.” Practice has also proven that there are many cases of hydraulic system failure and shortened life due to oil contamination. For this reason During the entire maintenance process, attention should be paid to pollution control and management. Source blocking, cleaning and filtration are effective measures to control pollution in hydraulic systems. Equipment assembly should be carried out in the workshop as much as possible, and precision parts should be assembled in a relatively closed dust-free environment.

3.2.1 Scientific cleaning of hydraulic system

It is necessary to focus on the three stages of cleaning work: The first is cleaning before the equipment is dismantled. In the cleaning field, high-pressure water guns are used to comprehensively clean the entire machine to remove accumulated oil and dust inside and outside the vehicle body. The second is cleaning of hydraulic components and hydraulic systems before installation. Hydraulic components, hydraulic auxiliary parts and hydraulic systems must be carefully cleaned to remove remaining chips, abrasive grains, yarn ends, oil stains, welding slag, rust flakes, peeling paint and plating materials attached to the surface. In addition to soaking and cleaning with kerosene, diesel or aqueous cleaning fluid, a more efficient ultrasonic cleaning machine can also be used to clean components with complex structures. The third is the cleaning of hydraulic components after they are installed in the system. Before commissioning, the hydraulic system circuit must be cleaned to remove dirt that entered the system during circuit installation and contamination from parts that have not been cleaned. At present, methods such as gravity cleaning, working fluid circulation cleaning and no-load operation cleaning are generally used.

3.2.2 Pressure hydraulic oil pipes must be prevented from contamination

When it is necessary to press a complete set of hydraulic oil pipes on site, while ensuring the quality of the press, it is necessary to prevent the outer rubber debris of the hydraulic oil pipe from remaining in the pipe. Hydraulic oil pipes should be flushed with a special pipe flusher, and rubber caps should be used to immediately seal both ends of the pipes, and they should be neatly sorted on the shelf for later use.

3.3 Spare parts management

Spare parts used for overhaul are specially purchased according to the demand plan. The spare parts purchased for each overhaul of rock drilling rigs are more than one million yuan. The value of the goods is high, so special parts should be managed exclusively. Under normal circumstances, it is managed by the maintenance equipment warehouse in the work area. When the overhaul site is far away from the maintenance equipment warehouse in the work area, a special storage space should be set up nearby and designated personnel should be arranged for safekeeping. Spare parts management at the overhaul site focuses on three aspects:

3.3.1 Arrival acceptance process

After the spare parts are notified of arrival, the on-site repair team must form an acceptance team together with the installation and management personnel in the work area, warehouse custodians, etc., and verify the parts one by one based on the relevant terms of the procurement contract and the relevant information on the parts list, and resolutely prevent parts from being shoddy or shoddy. Makeshift use, etc. After the parts pass the inspection, the acceptance team jointly signs the acceptance minutes and signs the parts arrival list for approval.

3.3.2 Storage and storage process

The circulation cycle of overhaul spare parts is generally within one year, and a special area should be set up in the warehouse for storage on special shelves, strictly separated from other maintenance equipment. Spare parts that pass the inspection should be sorted into categories in a timely manner, stored on shelves, and kept in a clean state. Maintenance team personnel should be on-site to assist when placing them. All overhaul spare parts should be marked with models, specifications, and usage parts to facilitate maintenance personnel to find them.

3.3.3 Receipt and delivery process

The principle of assembly on the same day of use must be adhered to, and spare parts shall not be stored at the maintenance site. The spare parts assembly record of the day must be consistent with the spare parts delivery record.

3.4 Old parts management

All old parts should be classified, stored centrally, labeled and managed on shelves to facilitate supervision and later review. It is necessary to continue to repair and recycle old parts that have continued use value. They can be used as spare parts in daily repairs and enter the circulation and use of normal spare parts.

3.5 Registration Statistics

The overhaul and repair cycle of rock drilling rigs is long, involves a wide range of specialties, and involves many repair and replacement parts. It is necessary to strengthen the registration and statistics work during the overhaul process in order to strengthen the maintenance plan progress management and trace the source of later problems. The replacement and debugging of components and seals during overhaul should be recorded and archived in detail. Under normal circumstances, registration statistics need to be completed, including equipment overhaul work log, disassembly and inspection record form, spare parts arrival and acceptance list, spare parts entry and exit registration form, outsourcing processing and repair acceptance form, assembly process registration form, and remaining spare parts registration after repair Table, used parts registration form, repair and waste spare parts list, etc.

4. Post-management after completion

After the repair team completes the overhaul work, documents and materials should be archived in a timely manner. Cooperate with the equipment overhaul and acceptance team of the superior agency to complete the inspection and acceptance of the equipment, and promptly carry out on-site rectification of the problems found.

When it is delivered to the construction site for use, in addition to explaining in detail the precautions for using the equipment after overhaul, the corresponding complete set of maintenance process data must also be handed over. The upgrading and transformation parts of the equipment should be highlighted, and the original parts manual should be supplemented and improved. Repeal parts, change parts, and add new parts. During the trial operation, the maintenance team must do a good job in early tracking of equipment failures, handle them promptly, and try to shorten the time from trial operation to stable operation of the equipment. The management of the subsequent fault handling process should be regarded as part of the overhaul work. After the overhaul work is completed, all process data should be bound into a volume and archived by the equipment management department.

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