JP5350131B2 - Drilling device and drilling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid the generation of delamination in advance by accurately estimating that the delamination is likely to generate when boring machining is performed on a hard-to-cut material by a drill 11. <P>SOLUTION: The boring device includes: the drill 11 boring an article 4 to be bored; a rotation driving means 12 rotating the drill 11; a feeding means 13 feeding the drill 11; a detecting means 23 detecting thrust force acting on the drill 11 during boring; a memory means 32 memorizing a relationship between a remaining distance corresponding to a distance from a surface on a hole outlet side to a shoulder portion of the drill 11 in the article 4 to be bored and the permissible thrust force of the drill 11; and a controlling means 32 determining whether the thrust force exceeds the permissible thrust force or not on the basis of the detected thrust force, the remaining distance according to the feeding amount of the drill 11, and the memorized permissible thrust force, and making the feeding means 13 return the drill 11 to an origin position when the thrust force exceeds the permissible thrust force. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The technology disclosed herein relates to a drilling device that drills a composite material such as a fiber reinforced plastic, which is a difficult-to-cut material, with a drill.

  For example, composite materials such as carbon fiber reinforced plastic (Cabon Fiber Reinforced Plastics: CFRP) are classified as difficult-to-cut materials in the field of cutting, and especially when CFRP having a laminated structure is drilled with a drill. Delamination may occur on the exit side of the hole. When CFRP is used as an aircraft part, high processing quality is required. Therefore, when delamination occurs, it must be repaired, which requires cost and time. Such delamination is caused by tool wear. For example, Patent Document 1 discloses a drill that suppresses the occurrence of delamination for a long time by extending the tool life.

JP 2009-39811 A

  However, even the drill disclosed in Patent Document 1 can cause delamination when the number of holes increases and tool wear proceeds. In order to surely avoid the occurrence of delamination, it is necessary to accurately predict that delamination is likely to occur due to the progress of tool wear, and to change the tool appropriately.

  The technology disclosed herein has been made in view of the above points, and the purpose of the technology is to cause delamination when drilling a difficult-to-cut material such as fiber reinforced plastic with a drill. It is to accurately predict that this is the case and to avoid the occurrence of delamination.

  In view of the above object, the inventors of the present application have repeatedly studied, and delamination that occurs on the outlet side of the hole reaches the vicinity of the surface corresponding to the outlet side of the drilled object. Thereafter, the portion where the thickness of the drilled object is reduced between the tip and the shoulder of the drill (that is, in the longitudinal section, it becomes a substantially triangular shape in which the thickness increases from the center of the hole toward the periphery. It was found that this occurs in a portion that is cantilevered on the peripheral side (hereinafter also referred to as a cantilever portion). Therefore, delamination occurs due to the magnitude relationship between the thrust force of the drill and the proof stress (shearing force) based on the strength of interlayer adhesion at the cantilever part, and the thrust force increases due to wear of the drill. When it does, it is estimated that delamination arises exceeding the yield strength in a cantilever part. In this way, the occurrence of delamination is not simply caused by the magnitude of the thrust force of the drill, but is also related to the proof stress in the cantilevered portion, and the proof strength is related to the feed amount of the drill (in other words, the hole being drilled This is the remaining distance until it completely penetrates the surface on the outlet side of the drilled object, and this remaining distance corresponds to the distance from the surface on the outlet side of the drilled object to the shoulder of the drill). As the feed amount of the drill increases and the remaining distance becomes shorter, the thickness of the cantilevered portion becomes thinner and the proof stress decreases.

  Therefore, the inventors of the present application obtain the relationship between the remaining distance and the allowable thrust force in advance, for example, by performing a load test in advance, and detect the thrust force of the drill during drilling. Based on whether or not the detected thrust force exceeds the allowable thrust force that is a function of the remaining distance, it is possible to accurately predict that delamination will occur and prevent delamination from occurring Focused on.

  A drilling device disclosed herein includes a drill for drilling a drilled object having a laminated structure, a rotation driving means for rotating the drill at a predetermined rotational speed, and the rotating drill as a drilled object. Corresponding to the distance from the surface on the hole exit side of the drilled object to the shoulder of the drill, the feed means for feeding at a predetermined feed speed, the detecting means for detecting the thrust force acting on the drill during drilling Storing the relationship between the remaining distance to be performed and the allowable thrust force of the drill, the detected thrust force, the remaining distance based on the feed amount of the drill, and the stored allowable thrust Based on the force, it is sequentially determined whether the thrust force exceeds the allowable thrust force, and when the thrust force exceeds the allowable thrust force, , And a, and a control means for causing return the drill to the origin position.

  According to this configuration, as described above, the relationship between the remaining distance until the hole being drilled completely penetrates the surface on the outlet side of the drilled object and the allowable thrust force is acquired in advance through, for example, a static load test. While being memorized in the memory means, while the drilling is being performed on the drilled object using the drill, the thrust force of the drill is detected by the detecting means.

  Then, the detected thrust force and the allowable thrust force corresponding to the remaining distance at that time are sequentially compared. When the thrust force is less than or equal to the allowable thrust force, drilling is continued assuming that delamination does not occur.On the other hand, when the thrust force increases due to wear of the drill and the thrust force exceeds the allowable thrust force, delamination occurs. Therefore, the drill is returned to the origin position to interrupt the drilling process. After that, the worn drill may be replaced with a new drill and the drilling process may be resumed.

  Therefore, in this perforating apparatus, it is possible to reliably and surely prevent delamination from occurring when a perforated object having a laminated structure is drilled.

  When the thrust force exceeds the allowable thrust force, the control means decreases the feed speed of the drill with respect to the feed means, and after the feed speed is reduced, the thrust force is reduced to the allowable thrust force. When the value exceeds, the feed means may be caused to return the drill to the original position.

  Since the thrust force of the drill is reduced by lowering the feed rate of the drill, it becomes less than the allowable thrust force and the occurrence of delamination can be avoided. That is, in this configuration, when the detected thrust force exceeds the allowable thrust force, first, the drill force is continued by lowering the thrust force by lowering the feed rate of the drill, and the feed rate is reduced, When the thrust force exceeds the allowable thrust force, the wear of the drill is severe, and if the drilling process is further continued, delamination may occur, and the drill is returned to the origin position. Then try to replace the drill. Therefore, this configuration is advantageous in terms of cost because the frequency of exchanging the drill is suppressed while avoiding the occurrence of delamination in advance and surely, as described above.

  The feed means may set the feed speed of the drill relatively fast until the feed amount reaches a predetermined amount, and relatively late after the feed amount reaches the predetermined amount.

  As described above, delamination is likely to occur immediately before the hole being drilled completely penetrates to the outlet side, and is difficult to occur until reaching the outlet side. In the period from the initial stage to the middle stage of machining, delamination does not occur even if the drill feed speed is set relatively high and the thrust force of the drill is increased. Conversely, setting the drill feed rate relatively fast suppresses drill wear and improves the efficiency of drilling.

  Thus, in the later stage of drilling after the feed amount reaches the predetermined amount, the delamination can be avoided by lowering the thrust force by relatively reducing the feed rate of the drill.

  The drilling method disclosed herein is a drilling method in which a drilled object having a laminated structure is drilled by a drill, and the drill rotating at a predetermined number of rotations is predetermined with respect to the drilled object. A step of feeding at a feed speed of, a step of detecting a thrust force acting on the drill, the detected thrust force, and a remaining distance corresponding to a distance from a hole outlet side surface of the drilled object to a shoulder portion of the drill And a step of sequentially comparing the allowable thrust force set based on the above and a step of returning the drill to the home position when the detected thrust force exceeds the allowable thrust force.

  According to this method, the drill thrust force is detected while the drilled object is being drilled, and the detected thrust force and the previously acquired remaining distance are supported. Compare the allowable thrust force. When the thrust force is less than or equal to the allowable thrust force, it is only necessary to continue the drilling process assuming that no delamination occurs. On the other hand, when the thrust force exceeds the allowable thrust force, the drill is returned to the origin position in order to interrupt the drilling process because delamination may occur. Accordingly, it is possible to avoid the occurrence of delamination when the perforated object having the laminated structure is subjected to the drilling process. When the drilling process is interrupted, the worn drill may be replaced with a new drill and the drilling process may be resumed.

  The drilling method further includes a step of reducing the feed rate of the drill when the thrust force exceeds the allowable thrust force, and after the feed rate is reduced, the thrust force exceeds the allowable thrust force. The drill may be returned to the origin position.

  When the detected thrust force exceeds the allowable thrust force, first the drill force is continued by reducing the thrust force by reducing the feed rate of the drill, and the thrust force of the drill is reduced while the feed rate is reduced. When the allowable thrust force is exceeded, return the drill to the home position and replace the drill. In this way, the processing when the detected thrust force exceeds the allowable thrust force is a two-step process, so that the occurrence of delamination can be avoided in advance and the drill replacement frequency is suppressed. This is advantageous in terms of cost.

  The drilling method may further include a step of reducing the feed rate of the drill when the feed amount of the drill reaches a predetermined feed amount.

  As described above, delamination is likely to occur immediately before the hole being drilled completely penetrates to the outlet side. Therefore, during the period from the beginning to the middle of the drilling process until the feed amount reaches a predetermined amount, drilling is performed. The feed rate is set relatively fast, and drilling is suppressed and the drilling efficiency is improved. On the other hand, in the latter stage of drilling after the feed amount reaches a predetermined amount, the occurrence of delamination is avoided by lowering the thrust force by relatively lowering the feed rate of the drill.

  As described above, since the drilling apparatus and the drilling method disclosed herein interrupt the drilling process according to the detected thrust force of the drill based on the relationship between the remaining distance and the allowable thrust force, delamination is performed. It is possible to reliably and reliably avoid the occurrence of.

It is a block diagram of a punching device. It is a figure explaining the generation | occurrence | production mechanism of delamination. It is a figure which shows an example of the relationship between remaining distance and permissible thrust force. It is a figure explaining switching of the number of rotations of a drill, and feed rate. It is a control flow executed by the control panel. The control flow is different from that in FIG. 5 executed by the control panel.

  Hereinafter, embodiments of a perforating apparatus will be described with reference to the drawings. The following description of the preferred embodiment is merely exemplary in nature.

(Embodiment 1)
FIG. 1 shows a schematic configuration of a perforating apparatus 1 according to the embodiment. The drilling device 1 is a power feed drill capable of automatically feeding a drill 11. The drill 11 is arranged on the main shaft X and drills a hole in the drilled object 4. The drill 11 is rotated about the main shaft X. AC servo motor (hereinafter referred to as “main shaft motor”) 12 for rotating the main shaft, and a feed AC servo motor (hereinafter referred to as “feed motor”) 13 for reciprocating the rotating drill 11 along the main shaft X. It is configured to be accommodated in the case 14. Here, the perforated object 4 to be perforated by the perforating apparatus 1 may be a CFRP plate material alone or a laminate of a CFRP plate material made of titanium or aluminum. A gap may be formed between the CFRP plate and the metal plate. Here, as shown in FIG. 4, the following description will be made assuming that the perforated object 4 is obtained by superimposing a titanium plate 42 on a CFRP plate 41 without a gap.

  The drill 11 is detachably attached to the distal end side of the drill main body 22 via a chuck 21. In this drilling device 1, a drill 11 having a different diameter is attached according to the processing content, and is replaced with a new drill 11 when wear of the drill 11 progresses.

  The feed motor 13 is disposed on the main shaft X on the proximal end side of the drill body 22. The feed motor 13 is driven to reciprocate the drill body 22 along the main axis X (see the arrow in FIG. 1). As a result, the drill 11 advances and retreats through the tip opening provided in the case 14 and moves relative to the drilled object 4 (see the one-dot chain line in FIG. 1). Between the feed motor 13 and the drill body 22, a feed torque detector 23 for detecting a thrust force acting on the drill 11 is disposed. The feed torque detector 23 outputs the detected thrust force to the control panel 32 described later.

  The main shaft motor 12 is arranged so as to be offset from the main shaft X so as to be arranged in parallel with the feed motor 13. Although not shown in detail, the spindle motor 12 is drivingly connected to the drill body 22 via a drive transmission mechanism 24 constituted by a belt or a gear set. The driving force of the spindle motor 12 is transmitted to the drill 11 via the drive transmission mechanism 24 and the drill body 22, and the drill 11 rotates around the spindle X. A rotational torque detector 25 that detects the rotational torque of the drill 11 is interposed between the spindle motor 12 and the drive transmission mechanism 24. The rotational torque detector 25 outputs the detected rotational torque to the control panel 32.

  The punching apparatus 1 also includes an operation panel 31 and a control panel 32. The operation panel 31 is connected to the control panel 32 so as to be able to transmit information. Although not shown, the person in charge of the drilling operation performs various operations including starting and stopping of the drilling apparatus 1 and information input. It has an operation unit that can The operation panel 31 is also provided with a display lamp 33 indicating the state of the drilling work, and the person in charge of the work looks at the display of the display lamp 33 to confirm that the drilling work is normally performed and abnormal. Can be recognized (including a drill 11 replacement request and the like, as will be described later).

  The control panel 32 controls the spindle motor 12 and the feed motor 13, and the number of rotations of the drill 11 is based on various signals from the operation panel 31 and signals from the spindle motor 12 and the feed motor 13. The feedback control of the spindle motor 12 is performed so as to be the target rotational speed, and the feedback control of the feed motor 13 is performed so that the feed speed of the drill 11 becomes the target feed speed. The control panel 32 also receives the rotational torque from the rotational torque detector 25 and the thrust force from the feed torque detector 23. The control panel 32 determines the overload of the main shaft motor 12 from the detected main shaft rotation torque, and determines the overload of the feed motor 13 from the detected thrust force, and stops the main shaft motor 12 and the feed motor 13. .

  The control panel 32 further detects the detected thrust force and the feed amount of the drill 11 (in other words, the shoulder portion of the drill 11 reaches the exit side surface of the drilled object 4 and the hole being drilled becomes the drilled object 4. On the basis of the remaining distance until it completely penetrates to the outlet side of the metal (see FIG. 2), the occurrence of delamination is predicted and control for interrupting the drilling process is also performed. Details of this control will be described later.

  FIG. 2 is a diagram illustrating a mechanism in which delamination occurs in a CFRP having a laminated structure. The delamination that may occur when drilling with a drill 11 is performed on a CFRP plate (drilled object) occurs on the outlet side of the hole, and the tip of the drill 11 corresponds to the outlet side of the drilled object 4. It can occur after reaching the vicinity. That is, in the state where the tip of the drill 11 has reached the surface on the outlet side of the drilled object 4, a portion where the thickness of the drilled object is reduced between the tip of the drill 11 and the shoulder (in FIG. 2, A generally triangular shape in which the thickness increases from the center of the hole toward the peripheral edge, and a cantilever portion that is cantilevered on the peripheral edge side is generated. When the thrust force of the drill 11 exceeds the yield strength based on the strength of interlayer adhesion in the cantilever portion, the cantilever portion is damaged and delamination occurs (see the white arrow in FIG. 2). Therefore, the occurrence of delamination involves not only the magnitude of the thrust force of the drill 11 but also the proof stress of the cantilever part, and the thickness of the cantilever part becomes thinner as the feed amount of the drill 11 increases as the drilling progresses. Therefore, the proof stress is reduced. That is, for example, as shown in FIG. 3, the allowable thrust force (thrust force that does not cause delamination) changes as the feed amount of the drill 11 increases, and the feed amount increases and the remaining distance decreases. The allowable thrust force becomes small.

  In order to avoid the occurrence of delamination, the thrust force of the drill 11 should not exceed the allowable thrust force based on the remaining distance. For this purpose, for example, the remaining distance and the allowable thrust force as shown in FIG. It is necessary to ask for a relationship. The relationship between the remaining distance and the allowable thrust force is, for example, preparing multiple types of test pieces having cantilever portions with different remaining distances, and using an anvil having a shoulder on the tip side in the same manner as a drill, It is obtained by performing a static load test in which a shear force of the cantilever part is measured by applying a thrust force to the cantilever part of the test piece. In this characteristic line, the longer the remaining distance, the thicker the cantilevered portion and the greater the proof strength, so the allowable thrust force also increases, and the shorter the remaining distance, the thinner the cantilevered portion. Since the yield strength is reduced and delamination can be achieved even with a small thrust force, the allowable thrust force is reduced. Therefore, the lower region sandwiching the characteristic line is a safe region where no delamination occurs, and the upper region sandwiching the characteristic line is a delamination generation region where delamination can occur.

  Further, this characteristic changes according to the drill diameter. When the drill diameter is relatively large, the inclination of the characteristic line becomes steep, and when the drill diameter is relatively small, the inclination of the characteristic line becomes gentle.

  The preset characteristic line for each drill diameter is stored in the control panel 32 through the operation panel 31. Further, the machining conditions are set and input in advance through the operation of the operation panel 31 and stored in the control panel 32. The machining conditions here include a feed rate, a rotation speed, a drilling length (cutting length), and the like associated with each drill diameter. Here, the rotational speed and feed rate of the drill 11 will be described. As described above, delamination can occur on the exit side of the hole, and therefore the thrust force of the drill 11 is made smaller than the allowable thrust force in the vicinity thereof. However, in order to reach that point, for example, it is not necessary to reduce the thrust force of the drill 11 by lowering the rotational speed or feed speed, and conversely, the rotational speed or feed speed is lowered to reduce the drilling time. If the length becomes longer, wear of the drill 11 will be promoted. Therefore, for example, as shown in FIG. 4, in this drilling device 1, control is performed to switch the rotation speed and feed speed of the drill 11 in accordance with the feed amount of the drill 11. Specifically, from when the tip of the drill 11 comes into contact with the inlet side surface of the drilled object 4 to start drilling, immediately before the tip of the drill 11 reaches the outlet side surface of the CFRP plate 41. In a first region (in other words, about 1 mm before) (in other words, a period from the initial stage to the middle stage in the drilling process for the CFRP plate material 41), the rotational speed of the drill 11 is set to a relatively high first rotational speed. And the feed rate is set to a relatively fast first feed rate. By doing so, the machining efficiency is improved, and wear of the drill 11 is suppressed, and the life of the drill 11 is extended.

  A second region (a hole in the CFRP plate 41 from the time immediately before the tip of the drill 11 reaches the exit side surface of the CFRP plate 41 until the shoulder of the drill 11 reaches the exit side surface). As described above, the latter stage of the drilling process is a period in which delamination can occur. Therefore, the rotation speed of the drill 11 is set to the second rotation speed (<first rotation speed), and the feed speed is set to the second feed speed. Speed (<first feed speed). Thus, in the region where delamination can occur, the thrust force of the drill 11 is reduced to suppress delamination.

  In the subsequent third region, that is, when drilling the titanium plate material 42 superimposed on the CFRP plate material 41, the rotation speed of the drill 11 is set to the third rotation speed suitable for drilling titanium and the feed rate is set to the first speed. Set to 3 feed rates. The rotation speed and feed speed stored in the operation panel 32 as processing conditions include the first to third rotation speeds and the first to third feed speeds, and the timing for switching the rotation speed and feed speed. Information regarding the feed amount of the drill 11 is also stored in the control panel 32 through the operation panel 31.

  Next, control related to drilling by the control panel 32 will be described with reference to the flowchart shown in FIG. When performing a drilling operation, the worker in charge first selects and operates a drill diameter to be used on the operation panel 31. In response to the selection operation, the control panel 32 reads the corresponding machining information and performs drilling on the drilled object 4. Here, the first to third rotation speeds and the first to third feed speeds in each of the first to third areas, the feed amount information of the drill 11 according to the change timing of the rotation speed and the feed speed, the drilling length (cutting) Length) and allowable thrust force information (see FIG. 3) corresponding to the selected drill diameter are read (step S11).

  In the subsequent step S12, the spindle motor 12 is controlled so that the rotational speed of the drill 11 becomes the target rotational speed in accordance with the first to third regions reached by the drill 11, and the feed speed of the drill 11 is also controlled. The feed motor 13 is controlled so that becomes the target feed speed. As described above, in the first region, the first rotation speed and the first feed speed, in the second region, the second rotation speed and the second feed speed, and in the third region, the third rotation speed and the third feed speed. The spindle motor 12 and the feed motor 13 are controlled so as to achieve speed.

  In step S13, based on the feed amount of the drill 11 obtained from the feed motor 13 (servo motor), it is determined whether or not the drill 11 has reached the second region. On the other hand, the process proceeds to S14, while if YES in step S14, the process proceeds to step S15. In step S14, it is determined whether or not drilling has been completed based on the read drilling length and the feed amount of the drill 11 obtained from the feed motor 13. If not, the process returns to step S12 to return to the hole. Continue drilling.

  In step S15 that has reached the second region, the detection value (thrust force) of the feed torque detector 23 is read, and in step S16, the remaining distance obtained from the detected value and the feed amount of the drill 11, and the remaining distance. Based on the allowable thrust force corresponding to (and drill diameter), it is determined whether or not the detected thrust force exceeds the allowable thrust force. When the allowable thrust force is exceeded (in the case of NG), delamination may occur as it is, so that the process proceeds to step S17, while when the allowable thrust force is not exceeded (in the case of OK). Since the delamination does not occur, the process proceeds to step S14 and the drilling process is continued.

  In step S17, while maintaining the rotation of the drill 11, the drill 1 is returned to the original position, and in the subsequent step S18, the drill 11 is stopped and a warning lamp is turned on in the display lamp 33. In this way, the operator is urged to replace the drill 11. In step S <b> 19, it is determined whether the person in charge has exchanged for a new drill 11 and has performed a restart operation on the operation panel 31. Until the drill 11 is replaced and the restart operation is performed, a warning lamp is displayed. If the restart operation is performed, the process returns to step S12. That is, drilling is continued with the new drill 11. If the machining is completed (YES in step S14), the drill 11 is returned to the origin, and the drilling process is terminated.

  As described above, in this drilling device 1, the wear of the drill 11 or the like is determined based on the thrust force of the drill 11 and the allowable thrust force set based on the proof stress of the cantilever portion near the exit of the hole in the drilled object 4. Accordingly, it is determined in step S16 that the thrust force of the drill 11 has increased to exceed the allowable thrust force, and in that case, the drilling process is interrupted to prompt replacement of the drill 11 (step). S17 to S19). In this way, it is possible to reliably and surely prevent delamination from occurring when the drilled object 4 having a laminated structure is drilled by the drill 11.

(Embodiment 2)
FIG. 6 shows a flowchart relating to another control executed by the control panel 32. First, in step S21, according to the selected drill diameter, the first to third rotation speeds and the first to third feed speeds, the rotation speed and the feed speed change timing in each of the first to third regions are related. Information on the feed amount of the drill 11, the drilling length (cutting length), and information on the allowable thrust force corresponding to the selected drill diameter are read. In the subsequent step S22, the spindle motor 12 is controlled so that the rotation speed of the drill 11 becomes the target rotation speed in accordance with the first to third regions reached by the drill 11, and the feed speed of the drill 11 is also controlled. The feed motor 13 is controlled so that becomes the target feed speed. In step S23, it is determined whether or not the drill 11 has reached the second region. If NO, the process proceeds to step S24. If YES, the process proceeds to step S25. . In step S24, it is determined whether or not the drilling process has been completed. If the drilling process has not been completed, the process returns to step S22 and the drilling process by the drill 11 is continued.

  In step S25 that has reached the second region, the detected value (thrust force) of the feed torque detector 23 is read, and in step S26, based on the detected value, the feed amount (remaining distance), and the allowable thrust force. Then, it is determined whether or not the thrust force exceeds the allowable thrust force. When the allowable thrust force is exceeded (when NG), the process proceeds to step S27, while when the allowable thrust force is not exceeded (when OK), the process proceeds to step S24 to continue drilling. To do.

  In step S27, the feed speed of the drill 11 is decreased by a predetermined amount set by the control of the feed motor 13, thereby reducing the thrust force of the drill 11 and continuing the drilling process. The amount of decrease in the feed rate may be set in advance for each drill diameter, for example. Then, the thrust force detected in the subsequent step S28 is compared with the allowable thrust force, and it is determined whether or not the thrust force exceeds the allowable thrust force. When the allowable thrust force is not exceeded (when OK), the process proceeds to step S24, and the drilling process is continued as it is. On the other hand, when the allowable thrust force is exceeded (NG), the process proceeds to step S29. If the drilling process is continued after shifting to step S24, and the detected thrust force exceeds the allowable thrust force again in the determination step of S26, the process proceeds to step S29 without shifting to steps S27 and S28. You can move to.

  In step S29, in order to replace the drill 11, the drill 11 is returned to the original position while maintaining the rotation of the drill 11. In the subsequent step S210, the drill 11 is stopped and the warning lamp of the display lamp 33 is turned on. In this way, the operator is urged to replace the drill 11. In step S <b> 211, it is determined whether the person in charge has replaced the new drill 11 and has performed a restart operation on the operation panel 31. Until the restart operation is performed after the replacement, a warning lamp is displayed. If the restart operation is performed, the process returns to step S22, and drilling is continued with the new drill 11. If the machining is completed (YES in step S24), the drill 11 is returned to the origin, and the drilling process is terminated.

  As described above, in the control of the second embodiment, when the thrust force of the drill 11 exceeds the allowable thrust force, the drilling process is continued while reducing the thrust force by the decrease in the feed speed of the drill 11 (step S27) When the thrust force exceeds the allowable thrust force after the feed speed is lowered, the drill 11 is returned to the origin position in order to interrupt the drilling process as in the control of the first embodiment (step S29). Therefore, the control according to the second embodiment is advantageous in terms of cost because the frequency of exchanging the drill 11 is reduced while the occurrence of delamination is avoided without fail.

  The drilling device is not limited to a feed drill having a feed mechanism as shown in the figure, and may be a so-called machine tool such as a machining center.

  Further, as described above, the material to be punched is not limited to a stack of CFRP plate and titanium plate, and the material to be punched is a stack of CFRP plate and aluminum plate. Alternatively, a single plate made of CFRP may be used. The above-described switching control of the rotational speed and feed rate of the drill 11 may be appropriately set according to the configuration of the drilled object.

  As described above, the drilling device and the drilling method disclosed herein allow drilling with a drill while reliably avoiding delamination in a drilled object (hard-to-cut material) having a laminated structure including fiber reinforced plastic. This is particularly useful for drilling where high quality machining accuracy is required for aircraft parts and the like.

DESCRIPTION OF SYMBOLS 1 Drilling apparatus 11 Drill 12 Main shaft motor (rotation drive means)
13 Feed motor (feed means)
23 Torque detector (detection means)
32 Control panel (control means, storage means)

Claims (6)

A drill for drilling a drilled object having a laminated structure;
A rotation driving means for rotating the drill at a predetermined number of rotations;
Feed means for feeding the rotating drill to the drilled object at a predetermined feed rate;
Detecting means for detecting a thrust force acting on the drill during drilling;
Storage means for storing the relationship between the remaining distance corresponding to the distance from the hole exit side surface of the drilled object to the shoulder of the drill and the allowable thrust force of the drill;
It is sequentially determined whether or not the thrust force exceeds the allowable thrust force based on the detected thrust force, the remaining distance based on the feed amount of the drill, and the stored allowable thrust force. And a control means for causing the feed means to return the drill to the original position when the thrust force exceeds the allowable thrust force. The perforating apparatus according to claim 1,
When the thrust force exceeds the allowable thrust force, the control means reduces the feed speed of the drill with respect to the feed means,
When the thrust force exceeds the allowable thrust force after the feed speed is lowered, the drilling device causes the feed means to return the drill to the original position. The perforation apparatus according to claim 1 or 2,
The feed means is a drilling device that sets the feed speed of the drill relatively fast until the feed amount reaches a predetermined amount, and relatively slow after the feed amount reaches the predetermined amount. A drilling method for drilling a drilled object having a laminated structure with a drill,
Feeding the drill rotating at a predetermined rotational speed to the drilled object at a predetermined feed rate;
Detecting a thrust force acting on the drill;
A step of sequentially comparing the detected thrust force and an allowable thrust force set based on a remaining distance corresponding to a distance from a hole exit side surface of the drilled object to a shoulder of the drill; and
A drilling method comprising: a step of returning the drill to the origin position when the detected thrust force exceeds the allowable thrust force. The drilling method according to claim 4, wherein
Further comprising the step of reducing the feed rate of the drill when the thrust force exceeds the allowable thrust force;
A drilling method in which the drill is returned to the original position when the thrust force exceeds the allowable thrust force after the feed speed is reduced. The drilling method according to claim 4, wherein
A drilling method further comprising a step of reducing the feed rate of the drill when the feed amount of the drill reaches a predetermined feed amount.

Images