Drilling machine

Abstract

To provide a drilling machine capable of suppressing a significant increase in costs and detecting the amount of movement of a rock drill with high accuracy.SOLUTION: A first reference position detector 26 is disposed in front of a drive sprocket 21 on a left side surface of a guide shell 10, and a second reference position detector 27 is disposed toward the rear of a center portion in the longitudinal direction on a right side surface of the guide shell 10. As will be described in detail later, a location of the second reference position detector 27 is a position where a second carriage 17 is detected when a first carriage 15 moves and a front end of a shank rod 18 reaches the vicinity of a rear end of a centralizer 13, as shown in Fig. 6. The location of the first reference position detector 26 is a position where the second carriage 17 can be detected when the second carriage 17 is located at a rear stroke end RSE.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a drilling machine for drilling blast holes in rock masses and the like. [Background technology]

[0002] Existing drilling machines for drilling blast holes in rocks and the like are equipped with various mechanisms and equipment to drill blast holes deep into the rocks, and these various mechanisms and equipment are operated appropriately to drill long blast holes. For this reason, drilling work requires complicated operations and a high level of skill, resulting in a large workload.

[0003] To address this issue, proposals have been made to reduce the labor required for drilling machines and to automate them. When automating drilling machines, in order to execute automated control reliably and safely, it is necessary to improve the accuracy of sensor technology that senses the operating status of components and equipment. For example, accurate detection of the amount of movement of the rock drill is essential to correctly detect the feed rate and drilling depth, or to properly position the rock drill at a stop position corresponding to a rod addition or removal operation.

[0004] For this reason, for example, Patent Document 1 discloses a technique for accurately measuring the amount of operation of the feed mechanism of a drilling machine. In the technology disclosed in Patent Document 1, a metal disk with notches at a specified interval on its periphery is attached to the feed motor of the feed mechanism, and a pair of proximity switches are arranged opposite the notches in the metal disk at an interval different from the interval of the notches. When the feed motor rotates, the proximity switches react alternately to the non-notched parts and notches of the metal disk to generate on-off pulse signals. The amount of movement of the rock drill is detected by counting the number of pulses in this on-off pulse signal. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-306678 Summary of the Invention [Problem to be solved by the invention]

[0006] In the technology disclosed in Patent Document 1, when the rock drill is moved at a speed exceeding the detection limit of the proximity switch, pulse skips occur, making it impossible to accurately detect the amount of movement. Also, when the rock drill is moved back and forth in small increments, the pulse count may be incorrect, and these counting errors may accumulate. In addition, automatic control in drilling machines is becoming more sophisticated year by year, and even higher accuracy is required for detecting the movement of the rock drill. However, in order to adopt a high-performance encoder in a drilling machine, it is necessary to satisfy specifications that can withstand the harsh working environment of the drilling machine, which results in a problem of significantly increasing costs.

[0007] In view of the above-mentioned problems, an object of the present invention is to provide a drilling machine that is capable of suppressing a significant increase in costs and is capable of detecting the amount of movement of the rock drill with high accuracy. [Means for solving the problem]

[0008] The first invention includes a guide shell attached to the boom tip of a traveling carriage, a first carriage carrying a rock drill and moving the guide shell forward and backward, a second carriage carrying a hose reel and moving the guide shell forward and backward, a feed mechanism moving the first carriage and the second carriage forward and backward, a feed mechanism operation amount detection unit that detects the operation amount of the feed mechanism, a reference position information calculation and storage unit that calculates and stores reference position information indicating the position of the rock drill on the guide shell based on the detection value of the feed mechanism operation amount detection unit, and a first reference position detection unit that detects that at least one of the second carriages is located at the rear stroke end of the guide shell, wherein the second carriage is arranged behind the first carriage and operates in accordance with the first carriage, the amount of movement of the second carriage is set to half the amount of movement of the first carriage, and when the first reference position detection unit detects that the first carriage or the second carriage is located at the rear stroke end, it resets the reference position information to a value indicating the rear stroke end.

[0009] A second invention is a drilling machine characterized in that when the first carriage described in the first invention is positioned at the rear stroke end, the second carriage is also positioned at the rear stroke end.

[0010] A third invention is a drilling machine which is provided with a second reference position detection unit which detects the position of the second carriage when the first carriage described in the first or second invention is advanced, and which is characterized in that when the second reference position detection unit detects the second carriage, the reference position information is reset to a value indicating a predetermined advanced position.

[0011] A fourth invention is a drilling machine according to the third invention, characterized in that the rock drill is provided with a shank rod at its front end, the guide shell is provided with a centralizer at its front on the drilling axis of the rock drill, and the position of the first carriage when the front end of the shank rod is located near the rear end of the centralizer is defined as the predetermined forward position.

[0012] A fifth invention is a drilling machine described in the third invention, characterized in that the first reference position detection unit and the second reference position detection unit are proximity sensors fixed to the guide shell, and the second carriage is equipped with a first dog for detection by the first reference position detection unit and a second dog for detection by the second reference position detection unit.

[0013] A sixth invention is a drilling machine characterized in that the first carriage described in the fifth invention reaches the front stroke end by advancing beyond the specified forward position, and when the first carriage advances from the specified forward position to the rear stroke end, the detection signal of the second dog is continuously detected. Effect of the Invention

[0014] According to the present invention, it is possible to provide a drilling machine that can suppress a significant increase in costs and can detect the amount of movement of the rock drill with high accuracy. [Brief description of the drawings]

[0015] [Figure 1] 1 is a diagram showing a configuration of a drilling machine according to an embodiment of the present invention; [Diagram 2] 1A and 1B are diagrams illustrating a configuration of a guide shell according to an embodiment of the present invention. [Diagram 3] 1 is a diagram showing a configuration of a feed mechanism according to an embodiment of the present invention; [Figure 4] FIG. 4 is a diagram showing the amount of movement of a dynamic sprocket according to one embodiment of the present invention. [Diagram 5]1A and 1B are a plan view and a side view, respectively, showing a guide shell when a rock drill according to an embodiment of the present invention is positioned at a rear stroke end. [Figure 6] 5A and 5B are a plan view and a side view, respectively, showing a guide shell when the rock drill according to one embodiment of the present invention is located at a second reference position. [Figure 7] 1A and 1B are a plan view and a side view, respectively, of a guide shell when a rock drill according to an embodiment of the present invention is positioned at a front stroke end. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The present invention will be described below with reference to the drawings as appropriate. Note that the drawings are schematic. Therefore, it should be noted that the relationship, ratio, etc. between thickness and planar dimensions may differ from the actual ones, and the drawings may include parts with different dimensional relationships and ratios. In addition, the embodiments shown below are examples of devices and methods for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention does not specify the materials, shapes, structures, arrangements, etc. of the components to the embodiments described below.

[0017] <Configuration and structure of drilling machine> First, the configuration and structure of the drilling machine will be described with reference to FIG. The drilling machine 1 includes a traveling carriage 2 and a work machine 7 , and the traveling carriage 2 includes a track frame 3 , an engine section 4 , an operator cabin 5 and a control unit 6 . The work machine 7 includes a boom 9 that can be rotated and raised and lowered, and a guide shell 10 that includes a mechanism for performing drilling work. A rod changer 11 and a rod magazine 12 are provided on the side of the guide shell 10.

[0018] Although illustrations and detailed description are omitted for the engine unit 4, it is equipped with an engine, a hydraulic pump, a flushing mechanism, and a dust collector inside. The engine is a drive source that generates the drive force required to operate the drilling machine 1. The hydraulic pump discharges pressurized oil using the drive force generated by the engine, and supplies the pressurized oil to the track frame 3, the work machine 7, the flushing mechanism, and the dust collector. The flushing mechanism supplies compressed air to the tip of the bit, which will be described later, to expel the cuttings from the hole. The dust collector collects the cuttings expelled by the flushing mechanism. The operator cabin 5 forms a cockpit in which an operator who operates the drilling machine 1 sits.

[0019] The control unit 6 includes a hydraulic and pneumatic pressure control device and a reference position information calculation and storage unit 8 . In particular, the reference position information calculation and storage unit 8 calculates and stores position information of the rock drill 14 based on the detection value of the feed mechanism 20 in the guide shell 10, which will be described in detail later. The rod changer 11 is a device for adding and withdrawing a drilling rod 19, which will be described later. A plurality of rods 19 are loaded in the rod magazine 12. The rods 19 loaded in the rod magazine 12 are transported between the drilling axis of the rock drill 14 and the rod magazine 12 by the rod changer 11, and the rods 19 are further added or separated. This enables the drilling machine 1 to drill long blast holes deep into the rock mass.

[0020] <Guide shell configuration and structure> Next, the configuration and structure of the guide shell 10 will be described with reference to Fig. 2. Note that the dashed line in the figure indicates the drilling axis. In the following description, the guide shell 10 is assumed to be oriented such that its length is aligned horizontally, and the side facing the operator cabin 5 in Fig. 1 (the left side in Fig. 2) is assumed to be the front.

[0021] An openable / closable centralizer 13 capable of holding a rod 19 is provided at the tip of the guide shell 10. Further, the tip of the guide shell 10 is provided with a foot pad P having a plurality of spikes extending forward. A first carriage 15 carrying a rock drill 14, a second carriage 17 carrying a hose reel 16, and a feed mechanism 20 are provided at the rear of the guide shell 10. The first carriage 15 and the second carriage 17 are attached so as to be able to move forward and backward on the guide shell 10 (they can move left and right in FIG. 2), and can be moved back and forth by operating the feed mechanism 20.

[0022] The rock drill 14 is equipped with a shank rod 18 at the front end, and is equipped with a hydraulically driven rotation mechanism and impact mechanism inside. Although not shown, a hose for supplying hydraulic oil to the driving parts of the rock drill 14, such as the rotation mechanism and impact mechanism, is wound around a hose reel 16. In the rock drill 14, a rod 19 can be attached to a shank rod 18, and the rotational force and impact force generated by the rotation and impact mechanism are transmitted to the rod 19. In particular, a drilling bit B is attached to the tip of the rod 19 (the left end in FIG. 2), which is located at the forefront when drilling. The striking force and rotational force generated by the striking mechanism and the rotating mechanism are transmitted to the bit via the rod 19, and the rock mass to be crushed is crushed by the transmitted striking force and rotational force. A thrust force is constantly applied to the main body of the rock drill 14 toward the rock mass by the feed mechanism 20, and the bit B penetrates deep into the rock mass while crushing it, and drills a blast hole in the rock mass.

[0023] <Feed mechanism configuration and structure> Next, the configuration and structure of the feed mechanism 20 will be described with reference to Fig. 3. In order to make the operation of the guide shell easier to understand, in the following figures, the structure of the guide shell 10 is shown in a simplified manner, and the rod 19 is not shown. The feed mechanism 20 includes a drive sprocket 21 rotated by a hydraulic motor at the rear end of the guide shell 10, and a guide sprocket 22 at the front end. In addition, a driven sprocket 23 is provided below the second carriage 17. A first chain 24 is attached so as to cover the drive sprocket 21, the guide sprocket 22, and the driven sprocket 23. The first chain 24 is configured in a ring shape with both ends fixed to the first carriage 15, and causes the first carriage 15 to move forward and backward as the drive sprocket 21 rotates.

[0024] In addition to the first chain 24, the feed mechanism 20 is provided with a second chain 25 that is tensioned in a straight line and has one end fixed to the center of the guide shell 10 and the other end fixed to the rear part of the guide shell 10. The second chain 25 meshes with the driven sprocket 23. When the driving sprocket 21 rotates and the first carriage 15 moves back and forth, the driven sprocket 23 moves a distance SM that is half the moving distance CM of the first chain 24 like a movable pulley, as shown in FIG. Referring again to Figure 3, the feed mechanism 20 is equipped with a conventional proximity sensor to detect its own actuation amount, and also has a feed mechanism actuation amount detection unit (hereinafter referred to as actuation amount detection unit 30) which is equipped with a metal plate with a notch formed therein and is located coaxially with the drive sprocket 21.

[0025] <First reference position detection unit and second reference position detection unit> Next, the first reference position detection unit and the second reference position detection unit will be described with reference to FIG. The guide shell 10 includes a first reference position detection portion 26 and a second reference position detection portion 27 which are proximity sensors. The first reference position detector 26 is disposed in front of the drive sprocket 21 on the left side surface of the guide shell 10, and the second reference position detector 27 is disposed toward the rear of the center portion in the longitudinal direction on the right side surface of the guide shell 10. As will be described in detail later, the location of the second reference position detector 27 is a position where the second carriage 17 is detected when the first carriage 15 moves and the front end of the shank rod 18 reaches the vicinity of the rear end of the centralizer 13, as shown in Fig. 6. The location of the first reference position detector 26 is a position where the second carriage 17 can be detected when the second carriage 17 is located at the rear stroke end RSE.

[0026] The second carriage 17 is provided with a first dog 28 in about a rear quarter of its length, and a second dog 29 in about a front third of its length. The first dog 28 is detected by the first reference position detection unit 26 when the second carriage 17 is located at the rear stroke end RSE. The second dog 29 is detected by the second reference position detection unit 27 when the first carriage 15 is located between the second reference position RP2 and the front stroke end FSE shown in FIG. 6 and the second carriage 17 is located within a predetermined range in the center of the guide shell 10. Hereinafter, the position where the first reference position detector 26 detects the first dog 28 is defined as a first reference position RP1, and the position where the second reference position detector 27 detects the second dog 29 is defined as a second reference position RP2.

[0027] <Operation of the drilling machine during drilling work> Next, the operation of the drilling machine 1 and the action of the control device of the drilling machine 1 will be described with reference to Figs. When performing drilling work, first, the drilling machine 1 shown in Fig. 1 is moved to the work position. After arriving at the work position, the work implement 7 is operated to set the position and angle of the guide shell 10. For example, when drilling a blast hole perpendicular to the ground, the angle of the guide shell 10 is adjusted so that it is perpendicular to the ground. After the position and angle are determined, the foot pad P is placed on the ground to stabilize the guide shell 10. During this time, the first carriage 15 is located at the rear stroke end RSE (first reference position RP1), and the second carriage 17 is also located at the rear stroke end.

[0028] After the footpad P is placed on the ground, the first carriage 15 is advanced while the rock drill 14 is operating. A rod 19, which is located at the front when drilling as shown in Figure 2, is attached to a shank rod 18 at the tip of the rock drill 14, and drills a hole by being pushed forward while receiving rotational and impact forces from the rock drill 14. During drilling, compressed air is sent from the tip of the bit B through the inside of the rod 19 from a flushing mechanism into the blast hole to expel cuttings.

[0029] When the first carriage 15 reaches the end of the forward stroke, the hole is drilled to a depth that will accommodate almost the entire rod 19 located at the front during drilling. If drilling is to be performed deeper, the first carriage 15 is moved to the end of the reverse stroke and the rod 19 is added. When the rod 19 is added, the second carriage 17 also moves following the movement of the first carriage 15, and reaches the first reference position RP1. The rod 19 is added by the rod changer 11 taking the rod 19 from the rod magazine 12 and moving it to the drilling axis of the rock drill 14, then moving the first carriage 15 forward and attaching the end of the new rod 19 to the shank rod 18.

[0030] After drilling to the desired depth while adding rod 19, the rod 19 is pulled out from the blast hole. At that time, the first carriage 15 is moved to the rear stroke end, the rod 19 is held by the rod changer 11, and stored in the rod magazine 12. The first carriage 15 is then advanced again to the front stroke end FSE, the rod 19 is attached, and then the carriage is moved to the rear stroke end RSE. This operation is repeated until the rod 19 located at the front during drilling is pulled out.

[0031] In this way, in the drilling operation, the rod 19 is pushed out in the depth direction by repeatedly operating the first carriage 15. At that time, the total amount of push-out of the rod 19 is calculated based on the value detected by the operation amount detection unit 30, but when detection is performed using the conventional disk and proximity sensor, as described above, missing pulses occur, causing errors in the detection value. Unless some measure is taken, this error is likely to accumulate and become larger the deeper the hole to be drilled, that is, the more repeatedly the first carriage 15 is moved.

[0032] <Action of the drilling machine according to this embodiment> Next, the operation of the drilling machine 1 according to the invention will be described with reference to Figs. In the initial state shown in FIG. 5, that is, when the thrust amount of the rod 19 shown in FIG. 2 is 0, the first carriage 15 and the second carriage 17 are located at the rear stroke end RSE (first reference position RP1) as shown in FIG. At this time, the detection value of the operation amount detection unit 30 is 0. In addition, since no operation is being performed, no error is generated or accumulated.

[0033] By operating the feed mechanism 20, the first carriage 15 moves to the vicinity of the rear end of the centralizer 13 shown in FIG. 6 (second reference position RP2), and the second carriage 17 moves to a position halfway through the stroke of the first carriage 15. At this time, it is assumed that an error occurs in the detection value of the operation amount detection unit 30. In that case, the position information of the rock drill 14 stored in the reference position information calculation storage unit 8 differs from the actual position of the rock drill 14 after it has moved. However, when the first carriage 15 moves to the second reference position RP2, the second reference position detection unit 27 detects that the second carriage 17 has reached a position halfway through the stroke of the first carriage 15, and therefore also indirectly detects that the first carriage 15 has reached the second reference position RP2.

[0034] When it is detected that the first carriage 15 has reached the second reference position RP2, the position information of the rock drill 14 is reset to the second reference position RP2. For example, if the shank rod 18 is located near the rear end of the centralizer 13 and the position at which the centralizer 13 changes to an open state is a position of 1800 mm, the position information of the rock drill 14 stored in the reference position information calculation storage unit 8 is also set to 1800 mm, so that the actual position and the value stored in the reference position information calculation storage unit 8 match. Thereafter, the second reference position detection portion 27 continues to detect the second dog 29 until the first carriage 15 reaches the front stroke end FSE.

[0035] Then, when the first carriage 15 moves to the rear stroke end RSE in order to add the rod 19, the state shown in FIG. 5 is again attained. Although the first carriage 15 will move backwards from the front stroke end FSE, the second reference position detection unit 27 continues to detect the second carriage 17, so the position information will not be reset again, preventing the direction of travel of the rock drill 14 from becoming unknown during operation.

[0036] It is also assumed that an error has occurred in the output value of the operation amount detection unit 30. In this case, the position information of the rock drill 14 stored in the reference position information calculation storage unit 8 differs from the numerical value after the rock drill has actually moved. However, when the first carriage 15 moves to the rear stroke end RSE, the second reference position detection unit 27 detects that the second carriage 17 has reached the first reference position RP1. When the first reference position detection unit 26 detects the second carriage 17, the position information of the rock drill 14 is reset to the rear stroke end RSE, i.e., to 0, so that the actual position and the value stored in the reference position information calculation memory unit 8 match.

[0037] <Effects> The drilling machine 1 according to the present invention is equipped with a first reference position detection unit 26 and a second reference position detection unit 27, and resets the position information of the rock drill 14 every time the rock drill 14 reaches the stroke end, so that the operation amount detection unit 30 can be calibrated frequently. This makes it possible to prevent errors from accumulating in the detection values, and makes it possible to detect the amount of movement of the rock drill 14 with higher accuracy than with conventional guide shells. The drilling machine 1 of the present invention is equipped with a second reference position detection unit 27 that detects the second carriage 17 when the first carriage 15 reaches the second reference position RP2, and can reset the reference position information to a value indicating a predetermined forward position. Therefore, the position information of the rock drill 14 can be reset not only at the first reference position RP1 but also at the second reference position RP2 on the forward side, improving the ability to prevent the occurrence of accumulated errors.

[0038] Furthermore, since the first reference position detection unit 26 is located in a position to detect the second dog 29 when the front end of the shank rod 18 of the rock drill 14 is located near the rear end of the centralizer 13, it is possible to determine that the first carriage 15 is moving forward while the second reference position detection unit 27 is detecting the second carriage 17, even before a pulse signal from the operation amount detection unit 30 is received immediately after the position of the first carriage 15 is reset to the second reference position RP2. Moreover, the detection signal of the first reference position detector 26 is generated only when the backward movement is performed. In this way, the operating direction of the feed mechanism 20 is also detected by detecting the position of the second carriage 17, which is advantageous in performing automatic control of the punching operation.

[0039] The drilling machine 1 according to the present invention detects the position of the rock drill 14 mounted on the first carriage 15 by detecting the position of the second carriage 17. In this detection method, the position of the target object is detected indirectly, so deviation in the amount of movement between the first carriage 15 and the second carriage 17 becomes a problem. However, the second carriage 17 always moves half the distance of the first carriage 15 by the feed mechanism 20, so the deviation in the amount of movement is extremely small even when the operation is performed multiple times. Therefore, the position of the first carriage 15 can be detected with high accuracy by detecting the position of the second carriage 17 as well.

[0040] The drilling machine of the present invention is capable of adding configuration functions without changing the structure of the operating amount detection unit 30 that has been used conventionally, and since the only configuration added is a proximity sensor, there is no significant increase in manufacturing costs. Both the first reference position detector 26 and the second reference position detector 27 are disposed rearward from the center of the guide shell 10. Therefore, they can operate in a better environment than the front of the guide shell, which is a particularly poor environment due to flying cutting powder, and are less susceptible to the effects of dust, etc., making it easier to maintain good detection accuracy. In addition, it is easier to reduce costs than when they are disposed at the front of the guide shell 10. The above-mentioned actions and effects make it possible to prevent a significant increase in costs and to provide a drilling machine that is capable of detecting the amount of movement of the rock drill with high accuracy.

[0041] <Modification> In the embodiment, the second dog 29 is enlarged so that the second reference position detection unit 27 detects the second carriage 17 while the first carriage 15 is located from the second reference position RP2 to the front stroke end FSE, but the implementation of the present invention is not limited to this structure. For example, even if the second reference position detection unit 27 changes from a detection state of the second dog 29 to a non-detection state when the first carriage 15 reaches the front stroke end FSE, there is no problem if an operating program is configured so that even if the second reference position detection unit 27 detects the second dog 29 while the first carriage 15 is moving backward, this is not reset to the second reference position RP2, as long as there is a separate means capable of detecting the operation direction of the feed mechanism 20.

[0042] In the embodiment, the second carriage 17 is provided with the first dog 28 and the second dog 29 for detection by the first reference position detection unit 26 and the second reference position detection unit 27, but the embodiment of the present invention is not limited to this configuration. Therefore, for example, the arrangement of the first reference position detection unit 26 and the second reference position detection unit 27 may be changed to detect the main body part of the second carriage 17. Moreover, the first reference position detection unit 26 and the second reference position detection unit 27 do not necessarily have to be proximity sensors, and for example, limit switches may be used.

[0043] In the embodiment, the second reference position detection unit 27 is disposed on the guide shell 10, but the second reference position detection unit 27 is not necessarily provided. Even in this case, the feed mechanism operation amount detection unit is calibrated by the first reference position detection unit 26. During the drilling operation, when the rod is pushed out, which particularly requires high detection accuracy of the operation amount, the first carriage 15 starts to operate from the rear stroke end RSE of the guide shell 10, so there is almost no effect on the drilling accuracy. [Explanation of symbols]

[0044] 1 Drilling machine 2 Travelling cart 3. Truck Frame 4. Engine Department 5 Operator Cabin 6. Control Unit 7 Work equipment 8 Reference position information calculation storage section 9. Boom 10 Guide Shell 11 Rod Changer 12 Rod magazine 13 Centralizer 14 Rock Drill 15 First Carriage 16 Hose reel 17 Second Carriage 18 Shank Rod 19 Rod 20 Feed mechanism 21 Drive sprocket 22 Guide sprocket 23 Driven sprocket 24 First Chain 25 Second Chain 26 First reference position detector 27 Second reference position detector 28 First Dock 29 Second Dock 30 Operation amount detection unit B bit P Footpad RP1 First reference position RP2 Second reference position CM travel distance SM travel distance FSE forward stroke end RSE Rear stroke end

Claims

1. A guide shell attached to the tip of the boom of the traveling cart; a first carriage that carries a rock drill and that can move the guide shell forward and backward; a second carriage carrying a hose reel and adapted to move forward and backward along the guide shell; a feed mechanism for moving the first carriage and the second carriage forward and backward; a feed mechanism operation amount detection unit that detects an operation amount of the feed mechanism; a reference position information calculation and storage unit that calculates and stores reference position information indicating the position of the rock drill on the guide shell based on the detection value of the feed mechanism operation amount detection unit; a first reference position detection unit that detects that at least one of the first carriage and the second carriage is located at a rear stroke end of the guide shell, the second carriage is disposed behind the first carriage and moves following the first carriage; the movement amount of the second carriage is set to half the movement amount of the first carriage, A drilling machine characterized in that the first reference position detection unit resets the reference position information to a value indicating the rear stroke end when it detects that the first carriage or the second carriage is located at the rear stroke end.

2. 2. The drilling machine according to claim 1, wherein when said first carriage is at the rear stroke end, said second carriage is also at the rear stroke end.

3. a second reference position detection unit that detects a position of the second carriage when the first carriage is moved forward; 3. The drilling machine according to claim 1, wherein when the second reference position detection unit detects the second carriage, the reference position information is reset to a value indicating a predetermined forward position.

4. The rock drill has a shank rod at a front end, The guide shell is provided with a centralizer at the front on the drilling axis of the rock drill, 4. The drilling machine according to claim 3, wherein the predetermined forward position is a position of the first carriage when the front end of the shank rod is located near the rear end of the centralizer.

5. the first reference position detection unit and the second reference position detection unit are proximity sensors fixed to the guide shell, The drilling machine according to claim 3, characterized in that the second carriage is provided with a first dog for detection by the first reference position detection unit, and a second dog for detection by the second reference position detection unit.

6. the first carriage advances beyond the predetermined forward position to reach a forward stroke end, 6. The drilling machine according to claim 5, wherein the detection signal of the second dog is continuously detected when the first carriage advances from the predetermined forward position to the rear stroke end.

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