The invention relates to a rotation unit for rock drilling, which rotation unit has no percussion device. The purpose of the rotation unit is to generate the required rotation for drilling equipment to be connected thereto, at the outermost end of which equipment there is a drill bit for breaking rock.
Further, the invention relates to a drilling unit and a method for rock drilling. The field of the invention is described in more detail in the preambles of the independent claims of the application.
Holes can be drilled in rock by means of various rock drilling machines. Drilling may be performed with a method combining percussions and rotation (percussive drilling), or drilling may be based on mere rotation without a percussive function (rotary drilling). Further, percussive drilling may be classified according to whether the percussion device is outside the drill hole or in the drill hole during the drilling. When the percussion device is outside the drill hole, the drilling is usually called top hammer drilling, and when the percussion device is in the drill hole, the drilling is typically called down-the-hole drilling (DTH). In a top hammer drilling machine, the percussion device and the rotation device are combined into one entity, whereas in a rotary drilling machine and DTH drilling machine, there is a rotation unit which is completely without a percussion device. This application is specifically directed to such a rotation unit without a percussion device and to the use thereof.
The rotation unit comprises a main shaft that is rotated around its longitudinal axis. Rotation force is generated by a rotating motor connected to the main shaft through a gear system. As the drilling progresses, more drilling tubes are connected to the drilling equipment and, correspondingly, disconnected after the drill hole has been finished and it is time to start drilling a new drill hole. The drilling tubes are provided with connection threads, due to which they require what is called a floating spindle that allows the threads to be screwed and unscrewed without simultaneous accurate control of the feeding movement. The floating spindle enables the required axial movement that results from the pitch of the connection threads. Floating spindles used nowadays are separate units which are connected to a rotation unit before the first drilling tube. Such separate floating spindle units have, however, turned out to cause problems to the durability of the equipment.
It is an object of this invention to provide a novel and improved rotation unit, rock drilling unit and method for rock drilling.
The rotation unit according to the invention is characterized in that the main shaft is supported to the body slidingly in the axial direction.
The rock drilling unit according to the invention is characterized in that the main shaft of the rotation device is supported to the body slidingly in the axial direction.
The method according to the invention is characterized by allowing the main shaft of the rotation unit to move axially in relation to the body of the rotation unit when the drilling equipment and components of the drilling equipment are connected and disconnected.
The idea is that the main shaft of the rotation unit is bearing-mounted on the body in such a way that it can slide an allowed, predetermined axial length of movement in relation to the body.
Thus, an advantage is that the axial movement of the main shaft allows the connection threads of the drilling equipment to be unscrewed and screwed without there being a need to arrange any separate floating spindle unit in the drilling equipment. Arranging a slide property in the rotation unit allows the structure to be more firm and durable than before.
The idea of an embodiment is that the main shaft is supported to the body in the radial direction in the portion of the front end by means of a front bearing, and in the portion of the rear end by means of an end bearing. Both bearings are slide bearings and may be of a suitable slide bearing metal, for example. The structure allows the axial distance between the bearings to be arranged relatively long. Owing to this, the crosswise forces transmitted from the drilling equipment to the main shaft during drilling can be received well to the firm body of the rotation unit. Further, the durability of the structure is improved by the opportunity to arrange the front and end bearings in oil-lubricated spaces.
The idea of an embodiment is that the main shaft is bearing-mounted on the body by means of a front bearing and an end bearing, the axial distance between these being great in relation to the diameter of the main shaft. The bearings have an axial bearing distance, and the main shaft has bearing diameters at the point of the bearings. According to observations, the bearing of the main shaft is particularly firm when the ratio of the bearing distance to the greatest one of the bearing diameters is at least 3:1. The bearing diameters may be equal or unequal at the front and end bearings. The bearing distance is the dimension between the functional middle points of the front and end bearings.
The idea of an embodiment is that the transmission members between the gear system and the main shaft comprise sliding members which allow axial movement of the main shaft without any axial forces being transmitted to the gear system. When there are no axial loads directed from the main shaft to the gear system or the rotating motor, the durability of the rotation unit is good.
The idea of an embodiment is that rotation force is transmitted to the main shaft from the portion of its rear end. There is more space for the transmission members at the rear end of the main shaft, whereby they can be dimensioned and positioned more freely than in solutions where rotation force is transmitted from the portion of the front end of the main shaft.
The idea of an embodiment is that the rotating motor and the gear system are positioned as an extension of the rear end of the main shaft. The rotating motor, gear system and main shaft are then positioned successively on the same axial line. Thus, the rotation unit, seen in the lateral direction, may be rather narrow. Although the length increases on the side of the rear end of the rotation unit, this has not turned out to do any harm to the structure or operation. Further, the rotating motor and gear system may be modules which can be easily and quickly detached and replaced with a new one without having to disassemble the rest of the rotation unit structure. There is plenty of space for handling the modules at the rear end of the rotation unit. It is also feasible to provide the rear end of the rotation unit with modules having different powers and other properties if it is desirable to affect the properties of the rotation unit.
The idea of an embodiment is that the outer periphery of the main shaft has at least one arranged to transmit axial feed force between the body and the main shaft. The feed flange has axial support surfaces which participate in transmitting axial forces. Further, the body has a sliding space at the location of the feed flange. The sliding space is an elongated annular space around the main shaft, having ends that define the sliding space in the axial direction. The front end and the rear end comprise support surfaces which may participate in transmitting axial forces.
The idea of an embodiment is that the feed flange and the sliding space at the location thereof are positioned in the portion of the front end of the main shaft. Then, axial forces are transmitted between the main shaft and the body as close to the front end of the rotation unit and the drilling equipment as possible. The axial forces do thus not stress the rear part of the main shaft or the components of the rotation unit that are positioned in the rear part. These aspects are also preferable with regard to the durability of the rotation unit.
The idea of an embodiment is that the feed flange is positioned in the sliding space on the front side of the front bearing supporting the main shaft. Thus, the front bearing transmits axial forces between the feed flange and the rear end of the sliding space when the feed is towards the drilling direction. The front bearing serves as a radial bearing of the main shaft and as an axial bearing. The front bearing is a slide bearing that is extremely capable of receiving great axial forces during drilling. The front bearing may be arranged in the sliding space slidingly in the axial direction, whereby it may be arranged to move together with the main shaft. Further, the sliding space may be oil-lubricated, which improves the durability of the front bearing even more.
The idea of an embodiment is that the structure of the rotation unit comprises an axial damper. The axial damper is thus integrated to form a part of the rotation unit. The axial damper may be used for damping vibration, impacts, shock waves and other axial stresses which affect the main shaft and are transmitted to the main shaft from the drilling equipment. Such an axial damper significantly reduces vibration and stress waves directed to the body and body parts from the drilling equipment through the main shaft, whereby less stress is directed to the components behind the axial damper. Further, the axial damper may also reduce stresses directed the components on the front side of the damper, i.e. on the side of the drilling equipment, at least to some extent.
The idea of an embodiment is that the axial damper comprises at least one end damper arranged at the end of the sliding space. The axial damper may comprise a rear end damper doing the damping in the drilling direction, and a front end damper doing the damping in the return direction. In some cases, the damper may comprise only a rear end damper. The advantage of an end damper is that its structure is simple and that it is inexpensive and requires little maintenance.
The idea of an embodiment is that the end damper is an annular piece made of a compressive elastic material. The end damper may be of a polymer material, such as suitable polyurethane. Such dampers have turned out resist-wear surprisingly well.
The idea of an embodiment is that the axial damper comprises at least one pressure-medium-operated damper element. Such an axial damper may have working pressure spaces into which pressure medium, such as hydraulic fluid, may be conducted which affects the working pressure surfaces in the working pressure spaces. It is further feasible for the axial damper to comprise one or more damping pistons arranged to affect the main shaft in the axial direction either directly or by means of appropriate intermediate pieces. The pressure of the pressure medium may be directed to the damping pistons to generate desired damping in the extreme positions of the sliding movement of the main shaft.
The idea of an embodiment is that there are connecting members at the front end of the main shaft of the rotation unit for rigid mounting in the axial direction. Thus, the drilling equipment is mounted on the main shaft without any axially directed sliding connection. The connecting members may comprise connection threads to which the drilling tube, an adapter piece or the like component can be attached. This embodiment reduces the loads directed to the connection between the main shaft and the drilling equipment.
The idea of an embodiment is that the outer periphery of the rear end of the main shaft comprises an axial set of grooves for transmitting rotation force. Further, around the rear end of the main shaft, there is a rotating sleeve the inner periphery of which comprises a corresponding axial set of grooves. Thus, between the outer surface of the rear end of the main shaft and the inner surface of the rotating sleeve, there is transmission connection allowing axial movement of the main shaft. The rotating sleeve is bearing-mounted on the body with axial bearings, whereby no axial forces are transmitted from the main shaft to the gear system through the transmission members. These features are preferable:with regard to the durability of the structure.
The idea of an embodiment is that the gear system is a planetary gear. The planetary gear may be physically rather small and also short in the axial direction, whereby it is easy to arrange at the rear end of the main shaft.
The idea of an embodiment is that the main shaft comprises a first main shaft part and a second main shaft part arranged on the same axial line and connected to each other. The connection between the main shaft parts is axially rigid. On the outer periphery of the rear end of the first main shaft part, there is a set of grooves by means of which rotation force can be transmitted to the main shaft. The front end of the second main shaft part, in turn, comprises a connection thread for attaching the drilling equipment. The main shaft is bearing-mounted on the body by means of the front bearing and end bearing of the first main shaft part only. The bearings are arranged at as great an axial distance from each other as possible, whereby they receive the crosswise loads well. Further, the feed flange may be arranged as a fixed part of the second main shaft part. Alternatively, the feed flange may be a separate piece, for example an annular flange, which is arranged between the main shaft parts.
The idea of an embodiment is that the portion between the front bearing and the end bearing comprises a pressure medium space surrounding the main shaft and in connection with a feed channel for pressurized air or the like pressure medium. The main shaft has one or more channels for conducting pressure medium from the pressure space into a centre channel in the main shaft and further along it to the drilling equipment to be connected to the main shaft. The pressure space around the main shaft may be isolated from the bearing spaces with shaft seals. Then, the pressure medium remains separate from the lubrication oil of the bearing spaces.
The idea of an embodiment is that the rock drilling unit comprises a carriage which is moved on a feed beam by means of a feed device. The body of the rotation unit is immovably attached to the carriage. Thus, the rotation unit and its body always move along with the carriage, there being no slidingly arranged body parts in the rotation unit.
The idea of an embodiment is that the rotation unit is intended for rotary drilling, in which drilling takes place by the effect of mere rotation and feed force without any percussion device.
The idea of an embodiment is that the rotation unit is intended for DTH drilling, in which the rotation unit and the percussion device are in opposite end portions of the drilling equipment. Hence, there is no percussion device in the rotation unit but it is in connection with the drilling equipment. The drill bit is typically attached directly to the percussion device.
The idea of an embodiment is that the axial position of the main shaft is monitored, and this information may be transmitted to a control unit that controls the handling device for drilling tubes in the rock drilling unit. Further, the information on the position of the main shaft may be utilized in controlling the screwing and unscrewing of the threads. The position of the main shaft may be monitored by means of one or more sensors or measuring devices.
The idea of an embodiment is that the axial position of the main shaft is monitored, and this position information is used as an aid in controlling the feed force during the drilling.
The idea of an embodiment is that the rotation unit comprises at least one axial damper as well as means for monitoring the axial position of the main shaft. The position information on the main shaft may be used for monitoring the condition of the axial damper. The control unit may comprise a control strategy for condition monitoring. The axial damper may comprise one or more damper elements made of a compressible material and having a planned functional compression area, for instance 10%. By means of the position information, it can be observed if this planned compression is exceeded, for example in cases where the damper element has permanently lost its elasticity and resilience or has been damaged in another way. Owing to this embodiment, damage of the axial damper can be observed in time.
The idea of an embodiment is that the main shaft is one integral shaft piece. The feed flange may be an integral undetachable part of the main shaft. Alternatively, the feed flange may be a piece formed separately, for example a ring -flange, which may be immovably attached to the shaft piece.
The idea of an embodiment is that the rotating motor is a hydraulic motor.
The idea of an embodiment is that the rotating motor is an electric motor.
The idea of an embodiment is that the rotation unit does not comprise- a gear system at all,but rotation force is transmitted to the main shaft by means of other transmission members. The rotation speed and torque of the rotating motor can be controlled in a versatile and accurate manner. The rotating motor is of the type called a direct drive motor. Motors of this type are available as hydraulically operated and electrically operated motors. As the gear system can be left out of the rotation unit, there are fewer components to be maintained and subject to damage. Further, the rotation unit can be made smaller.
The idea of an embodiment is that the transmission members are provided with members for promoting the flowing of lubrication oil in the lubrication space. Thus, a rotating hub or a rotating sleeve, for example, may be provided with screw-like members which generate a flow of lubrication oil by the effect of the rotating movement. In this way, durability of transmission surfaces, transmission components and bearings can be improved.
Some embodiments of the invention will be explained in greater detail in the attached drawings, in which
In the figures, some embodiments of the invention are shown simplified for the sake of clarity. Like reference numerals-refer to like parts in the figures.
It is seen in
The pressure medium, such as pressurized air, may be fed along a pressure channel 27 to the main shaft 17 and further to the drilling equipment.
Around the main shaft 17, there may be a pressure medium space 33, into which pressurized air or the like can be fed from the channel 27. The main shaft 17 comprises channels for conducting pressure medium to its front end and further to the drilling equipment 9. The pressure medium space 33 may be separated with axial seals 35 and 36 from the sliding space 26 and from a lubrication space 37 at the end bearing 21. The space 37 may be provided with lubricant from a channel 38, whereby also the end bearing 21 is oil-lubricated.
On the outer periphery of the rear end of the first main shaft part 17a, there is a set of grooves 19 to which a rotating sleeve 20 is connected, having a corresponding set of grooves. The set of grooves allows movement of the main shaft 17 in the axial direction. The rotating sleeve 20 is supported to the body 23 by bearings 39 and 40 in such a way that it is immovable in the axial direction. Rotation force can be transmitted to the rotating sleeve 20 by means of a rotating hub 41 connected to a shaft 42 or the like of the gear system 15. Of course, it may be feasible to combine the structure of the rotating sleeve 20 and rotating hub 41 into one entity. The gear system 15 and rotating motor 16 may be module-structured, and they may be arranged on an axial extension of the main shaft 17.
The embodiment shown in
It is seen in
It should be noted that in the above embodiments the rotating motor may a hydraulic motor or an electric motor. Further, a direct drive motor may also be used in the rotation units 7 shown in
in some cases, features disclosed in this application may be used as such, regardless of other features. On the other hand, when necessary, features disclosed in this application may be combined in order to provide varioust combinations.
The drawings and the related description are only intended to illustrate the idea of the invention. Details of the invention may vary within the scope of the claims.
Number | Date | Country | Kind |
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20115366 | Apr 2011 | FI | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/FI2012/050364 | 4/13/2012 | WO | 00 | 10/14/2013 |