JP2019151015A - Core drill device - Google Patents

Abstract

To provide a core drill device capable of detecting buried objects such as a reinforcing-bar at high precision without depending of the size of an aperture of a core bit.SOLUTION: A core drill device comprises: an automatic feeder having a cutting motor; and a core drill body having a drill motor rotationally driving a core bit, and further includes: a vibration sensor detecting vibration a value; and control means controlling at least either the drill motor or the cutting motor in cooperation with the vibration sensor. The control means detects contact with a reinforcing-bar or the like on the basis of vibration data including the vibration value of vibration frequency in accordance with the rotation number of the core bit and the number of teeth of a cutting tip, and stops the drill motor or the cutting motor.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a core drill device used for drilling / cutting a concrete structure or the like. More specifically, the present invention relates to a core drill device that can be controlled so as not to cut and break the embedded object when drilling a workpiece having an embedded object such as a reinforcing bar.

Conventionally, a core drill device has been used for drilling a concrete structure or stone. The core drill device is a device that rotates and drives a core bit, which is a cylindrical cutting tool, to form a circular hole in a work to be drilled. As an example, FIG. 6 shows a configuration of a general core drill device 200 and a drilling process. The core drill device 200 is fixed by fixing a base 201 on a work W such as a concrete structure. A support column 202 is fixed to the base 201, and a slide block 203 is attached to the support column 202. The slide block 203 can be moved up and down along the support column 202, and is moved up and down by the automatic feeding device 204. Automatic feeder 204, the cut motor M _S for internal, on-off and the lift speed of the lifting of the slide block 203 is controlled.

The work W is drilled by the core drill body 210. Core drill body 210 has a core bit C is a drilling tool, a drill motor M _D for rotating the core bit C as main components. In core drill body 210 of FIG. 6, are connected via a gear case 211 and a core bit C and drill motor M _D. Gear case 211 has a built-in gear for reducing the rotational speed of the drill motor M _D. The core drill main body 210 is brought into contact with or separated from the work W by raising and lowering the slide block 203 by the automatic feeding device 204.

  The core bit C is a cylindrical cutting tool. For example, a bit in which a hard material such as an abrasive is bound to the outer peripheral portion of the tip of a cylinder is used. In recent years, a core bit having a plurality of cutting tips (cutting blades) T to which a hard material such as diamond is bonded is often used in order to make the bit have a higher cutting force. The names of the constituent members of the core drill apparatus have some differences among those skilled in the art such as the manufacturer of the core drill apparatus. The names used above (for example, core drill main body, core bit, etc.) are examples, so even if other names are used, the members are the same or similar in terms of action, function, shape, etc. Is.

In the drilling operation by the core drill device 200, first, the base 201 is installed and fixed at an appropriate position on the work W, and then the device is installed. Thereafter, while rotating the core bit C drives the drill motor M _D, to activate the automatic feeder 204 to the slide block 203 is lowered along the column 202, perforating by pressing a core bit C to the work object. Thus in a normal core drilling device such, the operating current or the operating voltage at the cut motor M _S and drill motor M _D of the automatic feeder 204 is adapted to be monitored and adjusted. Then, during drilling operations, in accordance with the increase or decrease of the load of the drill motor M _D, the feeding speed of the cut motor M _S is controlled.

  The core drill apparatus described above is an indispensable working device at a construction site where a large number of drilling operations are required, and is widely used not only in new construction work but also in repair work and repair work. In particular, in repair / renovation work of reinforced concrete structures, drilling of floor surfaces and wall surfaces is important, and a core drill device is essential.

  By the way, in repair / renovation work of a reinforced concrete structure, there is a possibility that the strength of the entire concrete structure may be reduced. Therefore, it is desired to perform construction so as not to destroy existing embedded objects in the structure. Examples of the buried objects include reinforcing bars and various pipes (water pipes, gas pipes, etc.). In particular, for works aimed at seismic reinforcement of reinforced concrete structures, destruction of existing reinforcing bars should be avoided. In such construction, when the position of the embedded object in the work is grasped in advance from a drawing or the like, the construction can be advanced if the above-described core drill apparatus is appropriately used while avoiding them.

  On the other hand, when the position of the embedded object of the existing structure cannot be grasped in advance due to loss of the drawing or the like, it is not preferable to use the core drill device as it is. This is because the above-described core drill device continues drilling the workpiece by monitoring and controlling the drill motor and the cutting motor, and therefore, even if the core bit reaches the embedded object, the core drill device proceeds as it is.

  In view of this, in consideration of a drilling operation of a work including an embedded object such as reinforced concrete, a core drill apparatus having a control mechanism that prevents the core bit from breaking the embedded object has been developed. For example, Patent Document 1 discloses a core drill or a cutting motor when the cutting speed is detected based on the current or voltage of the cutting motor at the time of drilling, and the amount of change or rate of change exceeds a preset threshold. A core drilling device for stopping the operation is described. In the core drill device described in this document, when the core bit reaches the reinforcing bar in the work, it is noted that the current value of the cutting motor increases, and by detecting this, the cutting is stopped and the reinforcing bar Breakage can be prevented.

JP 2009-61749 A

  It has been confirmed that the core drill device described in Patent Document 1 described above can contribute to prevention of damage to buried objects in drilling work such as reinforced concrete. According to this core drill apparatus, when the core bit comes into contact with a reinforcing bar or the like, cutting can be stopped instantaneously. However, according to the study by the present inventors, it has been confirmed that the detection of reinforcing bars and the like may be difficult depending on the cutting conditions. In particular, in a core drill device using a large-diameter core bit, it has been confirmed that even if a reinforcing bar or the like is present, it tends to be misidentified and continue to be damaged.

  The present invention has been made based on the background as described above, and is a core drill apparatus including a core bit, and when drilling a work including an embedded object such as a reinforcing bar, the embedded object is more accurate than before. An object of the present invention is to provide a device that can detect and prevent the damage. In particular, the one that functions without being affected by the size of the core bit diameter is provided.

  The present inventors have considered that in the above-described conventional core drill device (Patent Document 1), the reason that the detection accuracy of the embedded object decreases when using a large-diameter core bit is the detection principle employed by the core drill device. As described above, in the conventional core drill device, the load (current / voltage) received by the cutting motor or the like is used as a reference, and the current (voltage) increases due to an increase in resistance when the core bit cuts a foreign object such as a reinforcing bar. This is used to control the device. There is no error in the detection principle itself. However, the load (current / voltage) of the cutting motor varies with an increase in the weight of the core bit. Usually, a large-diameter core bit has a large weight, and therefore, in a core drill apparatus to which a large-diameter core bit is applied, a current load is large from the stage during normal drilling where there is no contact with an embedded object. When the current value that is the basis of determination increases, the change or increase rate decreases, and it becomes difficult to determine whether there is contact with an embedded object.

  For the reasons described above, in the conventional core drill apparatus using the load of the cutting motor as a detection element, it is difficult to detect the reinforcing bars and the like while following the increase in the diameter of the core bit. Therefore, the present invention examined the behavior and factors that are behavior when the core bit comes into contact with an embedded object such as a reinforcing bar and that are not affected by the diameter and weight of the core bit.

  As a result of the study, the inventors of the present invention have come up with the present invention by paying attention to the change in the vibration value of the specific vibration frequency derived from the core bit as a detection standard for the buried object such as a reinforcing bar.

  That is, the present invention that solves the above-mentioned problems includes a base installed on a work piece, a support provided on the base, a slide block installed so as to be able to move up and down along the support, and the slide block. A core drill apparatus comprising an automatic feed device having a cutting motor to be driven, a core bit supported by the slide block and having a plurality of cutting tips at a tip thereof, and a core drill body having a drill motor for rotationally driving the core bit. A vibration sensor that detects a vibration value received by a part; and a control unit that controls at least one of the drill motor and the cutting motor in cooperation with the vibration sensor. From the detected vibration data, the vibration frequency derived from the core bit The vibration value of c extracts reference data including at least, on the basis of the reference data, a core drilling apparatus characterized by controlling at least one of the drill motor or the cut motor.

  As described above, the core drill apparatus according to the present invention includes a vibration sensor that detects vibration and a control unit that controls at least one of a drill motor and a cutting motor in cooperation with the vibration sensor. The present invention is intended to detect abnormal vibration that occurs when a core bit comes into contact with an embedded object in consideration of the characteristics of a recent core bit having a high cutting force. The control means appropriately processes the vibration data detected by the vibration sensor, detects the occurrence of the abnormal vibration, and controls and stops the drill motor or the cutting motor.

  Here, the abnormal vibration will be described. In recent years, core bits that have been developed and used have been mainly equipped with a hard cutting tip at the tip. A core bit provided with such a cutting tip has a high cutting force, and in particular, exhibits high machinability with respect to a workpiece having high hardness such as concrete or stone. On the other hand, buried objects such as reinforcing bars contained in reinforced concrete have many metal wires and pipes. Metal is a material having greater toughness than concrete or the like. And the cutting tip with which a core bit is equipped exists in the tendency for machinability to become low with respect to a metal with large toughness. That is, the cutting bit of the core bit has a characteristic that the cutting ability varies depending on the object to be processed, and a workpiece such as concrete is easy to cut, but an embedded object such as a reinforcing bar is difficult to cut.

  Therefore, when the core bit collides with an embedded object while drilling concrete containing a reinforcing bar, etc., the core bit rotates while contacting alternately with a place that is easy to cut (concrete etc.) and a place that is difficult to cut (rebar etc.), A speed change occurs during one rotation and abnormal vibration occurs. This abnormal vibration is clearly different from the steady-state vibration for drilling a workpiece such as concrete.

  Here, the rotating core bit generates vibration with a vibration frequency corresponding to the number of rotations. The abnormal vibration described above greatly changes the vibration value of the vibration of the core bit. Such a change in the vibration value at a specific vibration frequency caused by the abnormal vibration of the core bit occurs in the same manner even when the core bit diameter is large, so that the embedded object can be detected more effectively than before.

Then, when tracking the vibration frequency of the vibration caused by the core bit rotating in the work, the vibration frequency fc (Hz) is the rotation speed of the core bit RS (rpm) and the number of teeth of the cutting bit of the core bit is B. When (pieces), one of the following frequencies f ₁ and f ₂ (Hz) is obtained. When abnormal vibration occurs in the core bit, a significant change occurs in the vibration value of one or both of these vibration frequencies f ₁ and f ₂ .

The control means of the present invention extracts, from the vibration data detected by the vibration sensor, the vibrations having the vibration frequencies f ₁ and f ₂ as vibrations derived from the core bit, and reference data including at least them. Based on this reference data, the drilling operation is controlled. As specific contents of the operation by this control means, first, at least one of the drill motor and the cutting motor is controlled when the vibration value of the vibration frequency fc exceeds the threshold value at least once.

  Further, the control means of the present invention calculates the rate of change of the vibration value of the vibration frequency fc, and controls at least one of the drill motor and the cutting motor when the rate of change exceeds the threshold value at least once. May be

  And the vibration value of the vibration frequency fc by a core bit can be detected with the core drill main body with which the core bit was connected. Further, the vibration value of the vibration frequency fc by the core bit can also be detected by an automatic feeder that supports the core drill body. Therefore, the vibration sensor is preferably installed in either the core drill body or the automatic feeder. When installed in the core drill body, there is a merit that the detected vibration value is high. On the other hand, when a vibration sensor is installed in the automatic feeder, there is a merit in that the connection between the vibration sensor and the control means is simplified. As will be described in an embodiment described later, the vibration sensor and the control means can be easily mounted on the control board inside the automatic feeder. By installing the vibration sensor in the automatic feeding device, a simple device configuration can be achieved without considering cable routing. And even if a vibration sensor is installed in the automatic feeder, a sufficient vibration value can often be detected. For this reason, it is often preferable to install a vibration sensor in the automatic feeder.

  The vibration sensor installed in the present invention is preferably a vibration sensor capable of measuring in three axis directions (X axis, Y axis, Z axis). This is because the vibration value is reliably detected even if the shape of the drilling surface and the drilling direction are affected. In the drilling operation, when the vibration value of any axis is large, it is preferable to use the vibration value of that axis.

  The core drill apparatus according to the present invention has the same configuration as the conventional core drill apparatus except that it includes the vibration sensor and the control means described above. The configurations of the core drill body and the automatic feeder are the same as those of the conventional one.

  Moreover, in the core drill apparatus according to the present invention, it is possible to perform the drilling operation while detecting the embedded object without setting a limit on the core bit diameter to be used. In this regard, according to the study by the present inventors, in the core drill device that detects the embedded object based on the current / voltage change described in Patent Document 1, it was difficult to detect the core bit diameter exceeding 70 mm in diameter. In the present invention, it is possible to detect an embedded object even when a core bit having a large diameter of 70 mm or more, which is difficult to apply with this conventional technology, is used. The present invention is applicable to currently available core bits and can be used from a core bit with a diameter of 25 mm to a core bit with a diameter of 305 mm.

  The core drill apparatus according to the present invention controls the drilling operation based on a change in the vibration value of a specific frequency derived from the core bit, which is detected by an appropriately installed vibration sensor. This control means functions effectively regardless of the diameter of the core bit. ADVANTAGE OF THE INVENTION According to this invention, in the drilling operation | work of the workpiece which has embedded objects, such as a reinforced concrete, it can be drilled without damaging an embedded object.

The figure explaining the structure of embodiment of the core drill apparatus which concerns on 1st Embodiment. The circuit diagram when a control means is integrated in the automatic feeder of a core drill apparatus. The flowchart explaining the processing process of the vibration data by a control means in the core drill apparatus which concerns on 1st Embodiment. The flowchart explaining the processing process of the vibration data by a control means in the core drill apparatus which concerns on 2nd Embodiment. The figure explaining the structure of the core drill apparatus which concerns on 3rd Embodiment. The figure explaining the structure of the conventional core drill apparatus provided with an automatic feeder.

First Embodiment : A preferred embodiment of the present invention will be described below. FIG. 1 shows a configuration of a core drill apparatus 100 according to the present embodiment. The basic configuration of the core drill apparatus 100 is the same as that of the conventional core drill apparatus (FIG. 6). That is, the core drill apparatus 100 includes a support column 102 supported by the base 101 and an automatic feeding device 104 attached to the support column 102. Also, having a core drill body 110 with a core bit C and drill motor _{M D.} The core drill body 110 is supported by the slide block 103.

Automatic feeder 104 incorporates the cut motor _{M S.} Lifting on and off the lifting speed of the automatic feeder 104 is controlled by a cut motor M _S. Core bit C carries the drilling of the work material W is rotated by a drill motor M _D. A power cord P is connected to the automatic feeder 104, and is connected to a commercial power source or a generator outside the core drill device.

  In the present embodiment, a vibration sensor for detecting vibration is attached to the automatic feeder 104. In the present embodiment, the vibration sensor is fixed by being mounted on the control board of the automatic feeder 104. As the vibration sensor S1, a commercially available sensor such as a triaxial acceleration sensor can be applied. The control board is built in the automatic feeder 104. In FIG. 1, for convenience of explanation, the control vibration sensor S <b> 1 is displayed outside the automatic feeder 104.

Also, core drilling apparatus 100, in cooperation with the vibration sensor S1, and a control unit U for stopping the motor M _S or drill motor M _D for incision. The control means U can be a device in the form of a microcomputer capable of controlling a switching element such as a triac or a power element. In this embodiment, the automatic feeder 104 is mounted with a microcomputer serving as the control means U on the control board. In FIG. 1, for convenience of explanation, the control unit U (microcomputer) is displayed outside the automatic feeder 104 together with the vibration sensor S <b> 1.

FIG. 2 is an overall circuit diagram of the core drill device 100 according to the present embodiment when the microcomputer serving as the vibration sensor S1 and the control means U is mounted inside the automatic feed device 104 (external power source-automatic feed device-drill motor M). ₂ is a diagram of a control circuit of _D ). An acceleration sensor as the vibration sensor S1 and a microcomputer as the control means U are connected. The microcomputer (control means U) can control the power supply of the cutting motor and the drill motor. The microcomputer is programmed to take in vibration data from the vibration sensor S1, perform analysis (fast Fourier transform (FFT), etc.), calculation, determination, and the like. As in this embodiment, by mounting the vibration sensor S1 and the control means U on the control board of the automatic feeder 104, the apparatus configuration can be made compact and the construction of the control circuit can be simplified. Therefore, such a form is preferable.

Next, a drilling operation by the core drill apparatus 100 and a method for detecting an embedded object by the control means U will be described in this embodiment. Also in this embodiment, the basic process of the drilling operation is almost the same as the operation by the conventional core drill apparatus (FIG. 6). After connecting the core bit C having an appropriate diameter to the core drill body 110, the drilling position is positioned while fixing the base 101 to the work W. Thereafter, it drives the drill motor M _D is set to an arbitrary rotational speed, by operating the automatic dynamic feeder 104, to start the perforation is pressed against the workpiece material W a core bit C at a constant rate. Then, before the drilling is started or simultaneously with the drilling, the vibration sensor S1 and the microcomputer are activated and vibration detection is started. 1 includes an embedded object R such as a reinforcing bar.

Figure 3 is a flowchart illustrating the control unit U of this embodiment (the microcomputer), the start phase of the drilling operation (start), the process steps up to stopping the cut motor M _S or the drill motor M _D by rebar detection It is. When the drilling operation is started, the control means U takes in vibration data from the vibration sensor S1 (step A1). The control means U receives the number of rotations of the core bit and the number of teeth of the cutting tip, and the frequencies f ₁ and f ₂ are set in advance. The control unit U performs FFT (Fast Fourier Transform) processing on the vibration data, extracts vibration values (amplitude values) of the vibration frequencies f ₁ and f ₂ , and generates reference data (step A2). In this embodiment, since a triaxial acceleration sensor is used, reference data is generated from vibration data of an axis indicating the maximum amplitude most useful for analysis / determination.

Further, there is no restriction on which of the frequencies f ₁ and f ₂ is used as reference data for the oscillation frequency fc of the core bit after the FFT. Both f ₁ and f ₂ may be used as reference data, or one of them may be used as reference data. According to the study by the present inventors, the vibration value is usually f ₁ <f _{2 in} many cases. In the present embodiment, as the vibration frequency fc of the core bit, and the reference data on the vibration value of f _2.

  And the control means U sets the threshold value for determining a contact with an embedded thing with respect to the vibration value of the vibration frequency fc in the reference data of a drilling start stage (step A3). In this embodiment (FIG. 3), this threshold value is set to 1.5 times the vibration value at the drilling start stage.

  After the setting of the vibration frequency fc and threshold value serving as the reference data as described above, the determination process of the contact between the core bit and the embedded object is performed based on the vibration value of the reference data acquired according to the progress in the drilling operation (step A4). . In this determination process, it is determined whether or not the threshold value of the vibration value (amplitude) of the vibration frequency fc is exceeded within a certain time by a timer. In the determination process of this embodiment (FIG. 3), the timer is set at 0.2 seconds. When the amplitude exceeding the threshold value is generated at least once in 2 seconds and continuously for 2 seconds, it is determined that the reinforcing bar is perforated.

Vibration value of the reference data exceeds the threshold value, when it is determined that the core bit is in contact with the buried object, the microcomputer of the control unit U stops the cut motor M _S. The triac of the automatic feeder 104 can be stopped drill motor M _D by cutting off the power supply as an off (step A5).

After stopping the cut motor M _S and drill motor M _D, by moving the automatic feeder 104 in the drilling direction and the reverse direction, it is possible to confirm and proper processing of the presence or absence of buried objects in the perforated portion.

Second Embodiment : In this embodiment, the configuration of each member of the core drill apparatus is the same as that of the core drill apparatus (FIG. 1) of the first embodiment, and the configuration and program of a part of the microcomputer that is the control means U are changed. . In this embodiment, the contact determination between the core bit and the buried object during the drilling operation by the control means U is performed at a higher speed and more easily.

Here, the processing content of the control means U in this embodiment is demonstrated. The control means U of the present invention performs a determination process based on reference data including at least a vibration value of the vibration frequency fc derived from the core bit from vibration data from the vibration sensor. Here, the vibration frequency fc is preferably regarded as vibration frequencies f ₁ and f ₂ according to the number of rotations of the core bit and the number of teeth of the cutting tip. According to the study by the present inventors, in the vibration frequency band between the vibration frequencies f ₁ and f ₂ derived from the core bit, the increase in the vibration value due to the abnormal vibration of the core bit is _two of f ₁ and f ₂ . It is observed only by vibration, and the vibration values at other vibration frequencies do not increase so much. When the threshold value is set based on the vibration value measured in the band between the vibration frequencies f ₁ and f ₂ , the vibration value exceeding the threshold value due to abnormal vibration is at least one of the vibrations of f ₁ and f ₂ . It is. That is, it is unlikely that vibrations at other vibration frequencies than f ₁ and f ₂ exceed the threshold value. Therefore, even if the determination process is performed based on the vibration value in the band between the vibration frequencies f ₁ and f ₂ from the vibration data, the abnormal vibration due to the contact between the core bit and the embedded object can be detected.

Therefore, calculated upon the drilling operation, and the number of teeth of the cutting tip of the planned use core bits, based on the rotational speed that can be set, the minimum value of _{f 1 (f 1min)} and the maximum value of _{f 2} and _{(f 2max)} respectively, Vibration data based on them can be used as reference data. Specifically, vibration data including a vibration value in a band between vibration frequencies f _1min and f _2max is used as reference data from vibration data from the vibration sensor, and the vibration value and the change rate of the vibration value of the reference data are used. Based on this, threshold setting and determination processing can be performed. At this time, it is preferable to set a slight margin for the range to be extracted as reference data with respect to f _1min and f _2max . For example, while the calculated frequency of f _{1 min} is 0.5 to 0.9 times (more preferably 0.6 to 0.9 times), the frequency that is the lower limit of the reference data is set as the vibration frequency, while the calculated f _2max By making the frequency of 1.1 to 1.5 times (more preferably 1.1 to 1.4 times) the vibration frequency that is the upper limit of the reference data, a determination process without leakage can be performed.

Further, as described above, according to the study by the present inventors, when the vibration value of f _{1 and} the vibration value of f ₂ are compared, usually, f ₁ <f ₂ is often obtained. The relationship between the vibration values when abnormal vibration occurs is the same. Therefore, as a guideline for detecting abnormal vibration, the vibration value with a large vibration frequency f ₂ (f _2max ) should be emphasized. Therefore, as described above, when a vibration value in a predetermined vibration frequency band is extracted from vibration data, only the upper limit value is set, and vibration data having a vibration frequency f ₂ (f _2max ) or less is used as reference data. Thus, simple processing can be performed while maintaining reliability. As described above, when only setting the upper limit of the vibration frequency band of the reference data, the upper limit is preferably set to 1.1 to 1.5 times the calculated value of f _2max .

In the second embodiment, when the reference data is generated from the vibration data, only the upper limit setting of the vibration frequency band described above is performed. The specific setting process will be described. First, in the embodiment described later, a core bit having 4 to 22 teeth (B) (core bit diameter: 25 to 305 mm) is used. Further, the rotational speed (RS) of the core bit is scheduled to be 200 rpm to 1000 rpm. Therefore, the minimum value (f _1min ) of the vibration frequency f ₁ based on the rotation speed of the core bit is about 3.3 Hz (200 rpm / 60). On the other hand, the maximum value (f _2max ) of the vibration frequency f ₂ based on the rotation speed and the number of teeth of the core _bit is about 367 Hz (1000 rpm × _22/60 ). Therefore, the reference data needs to include at least a vibration value in a band with a vibration frequency of 3.3 Hz to 367 Hz.

In the present embodiment, while setting only the upper limit vibration frequency of the reference data, the upper limit value is set to 500 Hz (about 1.36 times f _2max (about 367 Hz in the example)). In the overall circuit diagram of FIG. 3, the control means U connects a low-pass filter set at a cutoff frequency of 500 Hz between the vibration sensor and the microcomputer (in the peripheral circuit of FIG. 3), and the vibration value at a vibration frequency of 500 Hz or less. Refers to. In the present embodiment, the vibration data having a vibration frequency of 500 Hz or less is set as reference data including a vibration value of the frequency fc derived from the core bit.

  In the second embodiment, the configuration of the reference data described above, the determination processing program based thereon, and the device configuration other than the low-pass filter installed in response thereto are the configurations of the first embodiment (FIG. 1). , Similar to FIG. Also in this embodiment, the vibration sensor S1 is mounted on the control board of the automatic feeding device 104, and the control means U is also mounted on the control board of the automatic feeding device 104 in the form of a microcomputer. The operation of the drilling operation in this embodiment is basically the same as that in the first embodiment.

Figure 4 is a flowchart for explaining the startup phase in the control unit U of this embodiment (microcomputer) (Start), the process steps up to stopping the cut motor M _S or the drill motor M _D by rebar detection. In the present embodiment, as described above, a vibration value having a vibration frequency of 500 Hz or less via the low-pass filter is captured as reference data (step B1). Then, similarly to the first embodiment, the vibration value of the axis indicating the maximum amplitude is used as reference data, and a threshold value of the vibration value is set (steps B2 and B3). The threshold in the present embodiment is 1.5 times the average vibration value at the drilling start stage.

In the control means U of the present embodiment, the processing content after the reference data range setting and threshold setting is the same as in the first embodiment. A process for determining the occurrence of abnormal vibration due to contact between the core bit and the embedded object is performed on the vibration value of the reference data acquired during the drilling operation (step B4). As in the first embodiment, a determination process using a timer (0.2 seconds) is performed. Then, when it is determined that the core bit is in contact with the buried object, the control unit U can stop the motor M _S and drill motor M _D for cut (step B5). This prevents the embedded object from being broken by the core bit.

3rd Embodiment : This embodiment is related with the core drill apparatus which changed the attachment position of the vibration sensor. FIG. 5 shows a configuration of a core drill apparatus 100 ′ according to the third embodiment. The core drill device 100 ′ has the same basic configuration as the core drill device 100 according to the first and second embodiments, such as the core drill body (core bit C, drill motor M _D ), automatic feed device 104, and the like. In this embodiment, to install a vibration sensor S1 to the exterior of the core drill motor M _D. On the other hand, the control means U is installed in the form of a microcomputer on a control board in the automatic feeder 104, as in the first embodiment. The vibration sensor S1 is connected to an analog input terminal of the microcomputer of the control means U by a cable. The vibration sensor S1 can also be installed inside the gear case 111 of the core drill body 110.

This core drill apparatus 100 'of this embodiment has the same configuration as the core drill apparatus 100 of the first embodiment except for the installation position of the vibration sensor S1. And the procedure of the work process in the drilling work and the processing content of the vibration data by the control means U (flow chart in FIG. 3) can be the same as those in the first embodiment. In this core drill device 100 ′ of this embodiment, since the vibration sensor S 1 is attached to the core drill body (drill motor M _D ), it is connected to the control means U (microcomputer) built in the automatic feeder 104. A cable is required. In the first embodiment in which the vibration sensor S1 is built in the automatic feeder 104, it can be said that the configuration of the first embodiment is preferable in that the cable is simplified in consideration of the fact that the cable is unnecessary.

  As mentioned above, although the core drill apparatus which concerns on 1st-3rd embodiment was demonstrated, the structure of a core drill apparatus is not limited above. For example, in the above-described embodiment, the vibration sensor S1 is mounted on the control board inside the automatic feeder 104, but the mounting position of the vibration sensor is not limited to this. The vibration sensor may be bonded and bonded to the outer (case) surface of the automatic feeder 104. Further, the control means U is not limited to being mounted on the control board of the automatic feeder 104. The control means may be in the form of an external device such as a control box equipped with a microcomputer, and may be installed outside the automatic feeding device 104.

  Also, the processing contents by the control means are not limited to the contents of the above-described flowcharts (FIGS. 3 and 4). In these figures, the vibration value of the vibration frequency fc or the vibration value of the vibration frequency equal to or lower than a predetermined upper limit value is processed as reference data. In the evaluation of this reference data, the microcomputer of the control means U You may evaluate by calculating the variation | change_quantity or change rate of the vibration value for every time.

  Here, the concrete drilling work of the reinforced concrete was performed using the specific example of the core drill apparatus according to the second embodiment described above, and the feasibility / accuracy of detection of the reinforcing bar as the embedded object was verified. In this example, a core drill device was configured by combining a commercially available core drill (trade name: Daimo Drill TS-402: manufactured by Shibuya Co., Ltd.) and an automatic feeder (AFS-V: manufactured by Shibuya Co., Ltd.). Then, a commercially available three-axis acceleration sensor (ADXL335: manufactured by Analog Devices) was mounted as a vibration sensor inside the automatic feeder of the core drill device.

  Reinforced concrete of 1500 mm (length L) × 1000 mm (width W) × 310 mm (thickness t) was prepared as reinforced concrete to be a work piece. In this reinforced concrete, reinforcing bars having a diameter of 20 mm are embedded in two stages at a pitch of 100 mm.

  The drilling operation was performed using four types of core bits having core bit diameters of 28 mm, 110 mm, 204 mm, and 305 mm. These core bits have cutting tips with diamonds sintered at their tips, and the number of teeth of the cutting tips is 4, 12, 16, and 22, respectively.

  Then, after the core drill apparatus was installed and fixed on the upper surface of the reinforced concrete by the above-described procedure, a drilling operation was performed. As described above, in the core drill device of the second embodiment, considering that a core bit having 4 to 22 teeth (B) (core bit diameter: 25 to 305 mm) is used at a rotation speed (RS) of 200 rpm to 1000 rpm, As the reference data including the vibration frequency fc of the core bit, it is assumed that the vibration data includes vibration values in a band of 3.3 Hz to 367 Hz. Then, a low-pass filter set at a cutoff frequency of 500 Hz is connected to the control means U, and based on the vibration value of the vibration frequency of 500 Hz or less, determination processing according to the flowchart of FIG. 3 is performed to detect the reinforcing bars. In this example, the drilling operation was performed one place at a time in the reinforced concrete from a small-diameter core bit while applying this program.

  As a result of drilling work under the above conditions, all three core bits used (diameter: 28 mm, 110 mm, 204 mm, 305 mm) were confirmed to stop the automatic feeder at the same time that the core bit contacted the reinforcing bar. It was done. Then, when the core bit was pulled up and the bottom of the perforated part was visually confirmed, a shallow scratch (depth of about 0.3 mm) was confirmed in the reinforcing bar, but there was no major damage. Therefore, it was confirmed that the reinforcing bar can be detected by the core drill device of the present example.

  As described above, according to the core drill device of the present invention, in the drilling work of a work including an embedded object such as reinforced concrete, the work can be performed while preventing the embedded object from being damaged. In particular, the present invention can effectively detect an embedded object even for a large-diameter core bit. The present invention is particularly useful at the construction site of existing / new reinforced concrete structures.

100, 100, 200 core drilling apparatus 101, 201 base 102, 202 struts 103 and 203 slide blocks 104, 204 Automatic feeder 110,210 core drill body 111, 211 a gear case _{M D} drill motor _{M S} cuts motor C core bit T Cutting Chip S1 Vibration sensor U Control means P Power cable W Workpiece

Claims (6)

A base installed on a workpiece, a support provided on the base, a slide block installed so as to be able to move up and down along the support, and an automatic feeding device having a cutting motor for moving the slide block up and down ,
In a core drill device comprising a core bit supported by the slide block and having a plurality of cutting tips at the tip, and a core drill body having a drill motor that rotationally drives the core bit,
A vibration sensor for detecting a vibration value received by the attachment site;
Control means for controlling at least one of the drill motor or the cutting motor in cooperation with the vibration sensor;
The control means extracts reference data including at least a vibration value of a vibration frequency fc derived from the core bit from vibration data detected by the vibration sensor, and based on the reference data, the drill motor or the cutting tool A core drill apparatus that controls at least one of motors. When the rotation speed of the core bit is RS (rpm) and the number of teeth of the cutting bit of the core bit is B (pieces), at least one of the frequencies f ₁ and f ₂ (Hz) obtained by the following formula is set as the vibration frequency of the core bit. The core drill apparatus according to claim 1, wherein the core drill apparatus is fc (Hz).

  The core drill device according to claim 1 or 2, wherein the control means controls at least one of the drill motor and the cutting motor when the vibration value of the vibration frequency fc exceeds the threshold value at least once.   The control means calculates a change rate of a vibration value of the vibration frequency fc and controls at least one of a drill motor and a cutting motor when the change rate exceeds a threshold value at least once. The core drill apparatus as described.   The core sensor according to any one of claims 1 to 4, wherein the vibration sensor is installed in either the core drill body or the automatic feeder. The core drill device according to any one of claims 1 to 5, wherein the vibration sensor is a vibration sensor in a triaxial direction (X axis, Y axis, Z axis).

Images