Tool drive device and method for manufacturing drilled parts

Abstract

To allow a user to set a rotation speed and a feeding speed of a tool more properly and easily when the user carries a tool drive device and sets the tool drive device on a workpiece to perform drilling.SOLUTION: A tool drive device is a drilling device which is carried by a user's hand to be set on a workpiece and used. The tool drive device includes: a spindle in which a holder for holding a tool is provided at a tip part; an electric motor for rotating the spindle; a guide provided with a positioning member for positioning the tool drive device on the workpiece; an electric actuator which moves the spindle forward or rearward in a rotation axis direction of the spindle relative to the guide; a sensor which measures cutting resistance transmitted from the tool to the spindle; and a controller which controls the electric motor and the electric actuator based on the cutting resistance so that a rotation speed and a feeding speed of the spindle become a rotation speed and a feeding speed set according to the cutting resistance measured by the sensor.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a tool driving device and a method for manufacturing a hole-processed product.

Background Art

[0002] There are some hand-held tool driving devices for hole processing with tools such as drills and reamers that have a tool feeding function (see, for example, Patent Documents 1 to 4). Also, a hand-held tool driving device equipped with two motors and capable of separately controlling the rotational speed and the feeding speed of the tool has been proposed (see, for example, Patent Document 5).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0004] When performing hole processing with a conventional hand-held tool driving device that feeds the tool in conjunction with the rotation of the tool, when the user determines the rotational speed of the tool according to the tool diameter and the workpiece material, the feeding speed becomes a speed corresponding to the rotational speed. On the other hand, in the case of a tool driving device in which the feeding speed of the tool can be set independently of the rotational speed, it is necessary for the user to determine the feeding speed of the tool in advance according to the tool diameter, the rotational speed, and the workpiece material.

[0005] Therefore, unless the user is familiar with the appropriate hole-drilling conditions, they cannot properly determine the tool's rotation speed and feed rate. In addition, when drilling holes in laminated materials made of multiple different materials, the user must pre-determine the appropriate tool rotation speed and feed rate according to the thickness of each material, and also change the tool's rotation speed and feed rate during machining when the material changes. As a result, there is a problem in that it is not easy to drill holes with the appropriate rotation speed and feed rate for each material.

[0006] Therefore, the present invention aims to enable users to more appropriately and easily set the rotational speed and feed rate of a tool when carrying a tool drive device, setting it on a workpiece, and performing hole drilling. [Means for solving the problem]

[0007] An embodiment of the present invention is a tool drive device for drilling holes, which is carried by a user by hand and set on a workpiece for use, comprising: a spindle having a holder for holding a drilling tool at its tip; an electric motor for rotating the spindle; a guide having a positioning member for positioning the tool drive device on the workpiece; an electric actuator for moving the spindle forward and backward relative to the guide in the direction of the spindle's rotation axis; a sensor for measuring the cutting resistance transmitted from the tool to the spindle; and a controller that controls the electric motor and the electric actuator based on the cutting resistance so that the rotation speed and feed rate of the spindle correspond to the rotation speed and feed rate measured by the sensor. A load cell, which measures the cutting resistance transmitted from the spindle in the rotation axis direction of the spindle, is connected to the rear end of the spindle as the sensor. It is.

[0008] Furthermore, the method for manufacturing a perforated product according to the embodiment of the present invention involves manufacturing a perforated product by performing hole machining on a workpiece using the tool drive device described above. [Brief explanation of the drawing]

[0009] [Figure 1]Front view of a tool drive device according to an embodiment of the present invention. [Figure 2] Top view of the tool drive device shown in FIG. 1. [Figure 3] Schematic partial longitudinal sectional view for explaining an example of the internal structure of the first electric motor shown in FIG. 1. [Figure 4] Exploded view showing the connection method of the first electric motor and the spindle shown in FIG. 1. [Figure 5] Enlarged partial longitudinal sectional view showing the connection method of the first electric motor and the spindle shown in FIG. 1. [Figure 6] Enlarged partial sectional view showing the connection method of the adapter and the first electric motor shown in FIG. 5. [Figure 7] Left side view of the pedestal shown in FIG. 4. [Figure 8] Diagram showing an example of positioning the tool drive device to the workpiece with the positioning bush shown in FIG. 1. [Figure 9] Enlarged left side view of the moving plate and the reinforcing frame shown in FIG. 1. [Figure 10] Enlarged view of the pusher, load cell and slide mechanism shown in FIG. 2. [Figure 11] Diagram showing a detailed configuration example of the controller shown in FIG. 1. [Figure 12] Diagram showing an example of an operation screen displayed on the display of the controller shown in FIG. 11. [Figure 13] Diagram for explaining the start position of the approach operation and the start position of the retreat operation of the tool that can be set through the operation screen shown in FIG. 12. [[ID=3!]]

Embodiments for Carrying Out the Invention

[0010] A tool drive device and a method for manufacturing a hole-processed product according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0011] (Configuration and Function of Tool Drive Device) FIG. 1 is a front view of a tool drive device according to an embodiment of the present invention, and FIG. 2 is a top view of the tool drive device shown in FIG. 1. D

[0012] The tool driving device 1 is a device for hole machining that can be carried by hand by a user and set on a workpiece W for use. Therefore, the tool driving device 1 is miniaturized and the number of components is reduced so that the weight of the tool driving device 1 is 20 kg or less. The tool driving device 1 has a function of rotating a hole machining tool T such as a drill or a reamer and feeding it in the direction of the tool axis AX.

[0013] For this purpose, the tool driving device 1 includes a holder 2 for holding the hole machining tool T, a spindle 3, a first electric motor 4 for rotating the spindle 3, a positioning member 5, a guide 6 for feeding the tool T, an electric actuator 7 for feeding the tool T, and a controller 8.

[0014] The holder 2 has an adapter for directly holding the tool T such as a collet chuck that can be attached and detached, or an adapter that is integrated. The holder 2 provided with an adapter for holding a drill is also called a drill chuck. The holder 2 is fixed to the tip of the spindle 3 so that the tool axis AX direction, which is the rotation axis direction of the tool T, and the rotation axis direction of the spindle 3 are on the same straight line. The spindle 3 is a shaft that transmits the torque generated by the first electric motor 4 to the holder 2.

[0015] FIG. 3 is a schematic partial longitudinal sectional view for explaining an example of the internal structure of the first electric motor 4 shown in FIG. 1.

[0016] In reality, it is possible to connect a gear 9 for adjusting the rotational speed and torque to the first electric motor 4 that applies torque to the spindle 3. That is, in reality, a speed reducer composed of the gear 9 can be connected to the first electric motor 4 to reduce the rotational speed while increasing the torque.

[0017] Therefore, as in the illustrated example, a coreless motor (ironless motor) 10 in which the gear 9 is arranged inside the housing 12 of the first electric motor can be used as the first electric motor 4. In other words, the gear 9 can be connected to the first electric motor 4 in the radial direction of the output shaft 11 of the first electric motor 4.

[0018] The coreless motor 10 has no core (iron core), and as illustrated in Figure 3, for example, it has a configuration in which a rotor 13 made of cylindrical magnets, a stator 14 made of cylindrical coils, and a rotating shaft 15 are arranged coaxially inside a cylindrical housing 12. The rotor 13 is fixed to the rotating shaft 15. The rotating shaft 15 is connected to the output shaft 11 via a reduction gear made of multiple gears 9 such as a pinion gear, sun gear, planetary gear and / or internal gear, and a part of the output shaft 11 protrudes from the housing 12.

[0019] Therefore, when the rotating shaft 15 rotates together with the rotor 13, torque adjusted via multiple gears 9 is output from the output shaft 11. Alternatively, the coil may be used as the rotor 13 and the magnet as the stator 14. Furthermore, by arranging the reduction gear, composed of multiple gears 9, inside the rotor 13, the reduction gear can be built into the coreless motor 10.

[0020] Generally, coreless motors have less output torque compared to typical electric motors with a core because they lack a core. For this reason, coreless motors were previously considered unsuitable as electric motors for rotating a tool T. In other words, it was considered more practical to connect a gear to an electric motor with a core in order to generate the torque required for cutting a workpiece W.

[0021] In contrast, the torque required for a tool drive device 1 for hole drilling, which is carried and used by the user by hand, is orders of magnitude smaller than that required for machine tools such as machining centers and milling machines, ranging from about 1 Nm to 20 Nm. For this reason, it has been found that a coreless motor 10 with gears 9 arranged inside the housing 12 can generate enough torque to be used for cutting. As a specific example, a coreless motor 10 that can output a rated torque of about 10 Nm to 15 Nm by arranging two stages of planetary gears in series inside the housing 12 is commercially available.

[0022] Therefore, although the output torque of the coreless motor 10 is still smaller compared to a typical electric motor with a core, the coreless motor 10 can incorporate a gear 9, making it possible to connect it to the spindle 3 without connecting a gearhead that houses the gear. As a result, the tool drive device 1 can be made smaller and lighter, making it easier to carry.

[0023] Of course, a motor with a core may be used as the first electric motor 4, and the gear 9 may be connected to the outside of the first electric motor 4. When the gear 9 is connected to the outside of the first electric motor 4, the rotation axis of the output shaft 11 of the first electric motor 4 and the rotation axis of the spindle 3 may be arranged in parallel, or they may be arranged to be perpendicular or otherwise non-parallel by using bevel gears or the like.

[0024] On the other hand, as shown in the figure, if a coreless motor 10 with a built-in gear 9 is used as the first electric motor 4, and the rotation axis of the output shaft 11 of the first electric motor 4 and the rotation axis of the spindle 3 are arranged on the same straight line, the tool drive device 1 can be made smaller and lighter as described above.

[0025] However, in addition to the cutting resistance in the rotational direction of the spindle 3, the spindle 3 also receives cutting resistance in the rotational direction of the spindle 3 from the tool T. The cutting resistance applied to the spindle 3 from the drilling tool T in the rotational direction of the spindle 3 is called cutting torque. In contrast, the cutting resistance applied to the spindle 3 from the drilling tool T in the rotational direction of the spindle 3 is called thrust resistance.

[0026] The spindle 3 needs to be connected to the output shaft 11 of the first electric motor 4. If the end face at the rear end of the spindle 3 is fixed to the end face of the output shaft 11, the cutting torque and thrust resistance from the tool T will be transmitted from the spindle 3 to the output shaft 11 of the first electric motor 4.

[0027] However, whether the first electric motor 4 is a coreless motor 10 or a motor with a core, the first electric motor 4 has a structure in which the output shaft 11 is supported only from the radial direction by radial ball bearings or gears. Therefore, the output shaft 11 of the first electric motor 4 can adequately withstand cutting torques of less than 20 Nm transmitted from the spindle 3, but may not be able to adequately withstand thrust resistance. Specifically, if the thrust resistance applied to the output shaft 11 becomes excessive and exceeds the allowable range of the first electric motor 4, the central axis of the output shaft 11 may become eccentric, and the quality of hole machining may deteriorate.

[0028] Therefore, the output shaft 11 and spindle 3 can be connected in such a way that torque is transmitted between the output shaft 11 of the first electric motor 4 and the spindle 3, while thrust resistance is not transmitted from the spindle 3 to the output shaft 11 of the first electric motor 4.

[0029] Figure 4 is an exploded view showing the connection method between the first electric motor 4 and the spindle 3 shown in Figure 1, and Figure 5 is an enlarged partial longitudinal cross-sectional view showing the connection method between the first electric motor 4 and the spindle 3 shown in Figure 1.

[0030] As illustrated in Figures 4 and 5, a thrust bearing 16 is mounted on the housing 12 of the first electric motor 4, and the spindle 3 can be brought into contact with the thrust bearing 16 so that the thrust resistance transmitted from the tool T to the spindle 3 is applied to the thrust bearing 16. The thrust bearing 16 does not need to be fixed to either the housing 12 or the spindle 3; it is sufficient to simply position the thrust bearing 16 in an appropriate location so that the thrust resistance from the spindle 3 is transmitted to the thrust bearing 16.

[0031] While the thrust bearing 16 is annular, the rear end of a typical spindle 3 is rod-shaped. Therefore, an adapter 17 with an annular flange 17A corresponding to the diameter and shape of the thrust bearing 16 is connected to the end of the spindle 3 on the first electric motor 4 side, allowing the spindle 3 to come into contact with the thrust bearing 16 via the adapter 17. This allows the thrust resistance to be received by the housing 12 of the first electric motor 4, rather than by the output shaft 11 of the first electric motor 4. The adapter 17 can be joined to the rear end of the spindle 3 by screws, welding, press-fitting, etc., so as to transmit torque and cutting resistance.

[0032] Furthermore, if the first electric motor 4 is a coreless motor 10 with a built-in gear 9, as shown in the figure, the spindle 3 is connected to the housing 12 of the first electric motor 4 with a thrust bearing 16 in between, without connecting the gearhead. However, if the first electric motor 4 is a motor with the gear 9 connected externally, the spindle 3 can be connected to the gearhead housing the gear 9 with a thrust bearing 16 in between.

[0033] The thrust bearing 16 is a bearing capable of receiving axial loads, and there are ball bearings and roller bearings. A ball bearing has a configuration in which multiple balls are arranged to roll between two thrust washers 16A, while a roller bearing has a configuration in which multiple rollers 16B are arranged to roll between two thrust washers 16A, as illustrated in Figure 5.

[0034] In the case of ball bearings, the wear of the balls progresses more slowly than the wear of the rollers 16B, making them suitable for high-speed rotation. On the other hand, rollers 16B, which make contact with the thrust washer 16A in a straight line, offer superior stability compared to balls, which make contact in a curved or point manner. Therefore, using roller bearings at low rotational speeds leads to improved hole machining quality. The rated rotational speed of the coreless motor 10 with a built-in gear 9 is generally less than 500 rpm. For this reason, as illustrated in Figure 5, a roller bearing in which multiple rollers 16B roll can be used as the thrust bearing 16.

[0035] Figure 6 is an enlarged cross-sectional view showing the connection method between the adapter 17 and the first electric motor 4 shown in Figure 5, and Figure 7 is a left side view of the base 18 shown in Figure 4.

[0036] In order to transmit the torque output from the output shaft 11 of the first electric motor 4 to the spindle 3, while ensuring that the thrust resistance from the spindle 3 is received by the thrust bearing 16 rather than by the output shaft 11, it is necessary not only to place the thrust bearing 16, but also to ensure that the annular support surface of the flange 17A formed on the adapter 17 attached to the rear end of the spindle 3, with the rotation axis direction of the spindle 3 as the normal direction, is in contact only with the thrust bearing 16, and that the surface of the output shaft 11 with the rotation axis direction as the normal direction is not in contact with the adapter 17.

[0037] If the thickness of the thrust bearing 16 in the direction of rotation is greater than the protrusion length of the output shaft 11 from the housing 12, then if one thrust washer 16A of the thrust bearing 16 is positioned in direct contact with the housing 12, the other thrust washer 16A of the thrust bearing 16 will protrude beyond the end face of the output shaft 11. Therefore, the flange 17A of the adapter 17 at the rear end of the spindle 3 can be made to contact only the thrust washer 16A without contacting the end face of the output shaft 11.

[0038] However, the thickness of the thrust bearing 16 in the direction of rotation is often thinner than the length of the output shaft 11 protruding from the housing 12. Therefore, as illustrated in Figures 4 to 6, the thrust bearing 16 can be positioned on the outside of the output shaft 11 protruding from the housing 12 of the electric motor 4, with an annular base 18 in the direction of rotation of the spindle 3, so that the sum of the thickness of the thrust bearing 16 and the thickness of the base 18 is thicker than the length of the output shaft 11 protruding from the housing 12.

[0039] In other words, an annular base 18 can be inserted as a shim between the thrust bearing 16 and the housing 12. The annular base 18, which is formed around a through hole for the output shaft 11, has multiple stepped through holes for fixing with bolts, as shown in Figures 5 to 7, so that the base 18 can be fixed to the housing 12 with bolts.

[0040] This allows at least a portion of the thrust washer 16A on the spindle 3 side of the thrust bearing 16 to protrude further toward the spindle 3 than the end face of the output shaft 11 on the spindle 3 side. Then, the flange 17A of the adapter 17 for contacting the thrust bearing 16 can be brought into contact with the thrust washer 16A on the spindle 3 side, and the flange 17A can be fixed to the output shaft 11 with bolts while a gap 19A is created between the flange 17A and the end face of the output shaft 11.

[0041] This allows the torque of the output shaft 11 to be transmitted to the spindle 3 via the adapter 17, while the thrust resistance can be transmitted from the spindle 3 to the housing 12 of the first electric motor 4 via the adapter 17, thrust bearing 16, and base 18.

[0042] In the illustrated example, the end of the output shaft 11 of the first electric motor 4 is cylindrical, and the end face of the output shaft 11 is annular. Therefore, a cylindrical projection with a step is formed on the rear end of the adapter 17 to insert it into the inside of the cylindrical output shaft 11 while maintaining coaxiality so that the rotation axis of the adapter 17 and the rotation axis of the output shaft 11 are on the same straight line. In other words, the circular rear end face of the adapter 17 is located behind the annular support surface formed on the rear end side of the flange 17A.

[0043] Even in such cases, a gap 19B is provided between the rear end surface of the adapter 17, with the rotation axis direction of the adapter 17 being normal to the surface of the output shaft 11, and the rotation axis direction of the output shaft 11 being normal to the surface of the output shaft 11, so that thrust resistance is not transmitted from the adapter 17 to the output shaft 11. On the other hand, in order to ensure the coaxiality of the adapter 17 and the output shaft 11, the side surface of the cylindrical rear end of the adapter 17 and the inner surface of the cylindrical output shaft 11 are in contact in the radial direction of rotation, and an O-ring may be placed between them.

[0044] Furthermore, if the end of the output shaft 11 is cylindrical, the rear end of the adapter 17 should be cylindrical, and the tip of the output shaft 11 should be inserted into the inside of the adapter 17, making contact only in the radial direction.

[0045] Thrust resistance is transmitted from the spindle 3 to the housing 12 of the first electric motor 4 via the adapter 17, thrust bearing 16, and base 18. However, the strength of the housing 12 of the first electric motor 4 is not designed to withstand thrust resistance over the same area as the cross-sectional area of ​​the spindle 3. Therefore, it is preferable to transmit the thrust resistance to the housing 12 over the largest possible area. In other words, it is preferable to transmit the thrust resistance to the housing 12 with the smallest possible pressure.

[0046] To achieve this, it is important to use a thrust bearing 16 with the largest possible thrust washer area 16A. In other words, it is desirable to use a thrust bearing 16 having a thrust washer 16A with a large outer diameter and a small inner diameter. In fact, when a thrust roller bearing with an outer diameter of 70 mm and an inner diameter of 50 mm was placed on the outside of an output shaft 11 with a diameter of 50 mm, with a base 18 in between, it was confirmed that it could withstand approximately 10 times the thrust resistance compared to when the output shaft 11 received thrust resistance without a thrust roller bearing.

[0047] Furthermore, thrust resistance can also be received by supporting the output shaft 11 or spindle 3 of the first electric motor 4 with multiple radial bearings connected in series, provided there are enough radial bearings. However, since radial bearings do not have a structure that can withstand axial loads, it becomes necessary to connect a large number of radial bearings, which significantly increases the axial length compared to the case where a thrust bearing 16 is arranged. For this reason, from the viewpoint of miniaturizing and lightening the tool drive device 1, it is preferable to pass the output shaft 11 of the first electric motor 4 inside the thrust bearing 16 and receive thrust resistance with the thrust bearing 16.

[0048] In order to feed the tool T and spindle 3 toward the hole machining position in the workpiece W, it is necessary to position the tool drive device 1 relative to the workpiece W. The positioning member 5 is a member for positioning the tool drive device 1 relative to the workpiece W. In the example shown in Figures 1 and 2, a positioning bush 20 having a flange-like portion at its rear end is provided at the tip of the guide 6 as the positioning member 5, but other positioning members 5 such as a fixing device or concentric collet disclosed in Japanese Patent Application Publication No. 2014-008586 may also be provided.

[0049] Furthermore, the concentric collet is a positioning member 5 with a centering function that has multiple slits and whose diameter expands when a collet bush is inserted inside. The member provided at the tip of the tool drive device 1 is also called a nosepiece, and the positioning bush 20 provided as part of the nosepiece is also called a bushing tip.

[0050] The guide 6 can have a structure in which, for example, a front-end plate 6A and a rear-end plate 6B are connected by two shafts 6C. The two shafts 6C are arranged parallel to each other so that their longitudinal direction is the feeding direction of the tool T and the spindle 3. The positioning bush 20 can then be fixed in front of the front-end plate 6A in the forward direction of the spindle 3 so that the central axis of the through-hole of the positioning bush 20 is collinear with the feeding direction of the tool T and the spindle 3, as well as the rotation axis of the tool axis AX and the spindle 3.

[0051] On the other hand, the rear end plate 6B can be fixed to the housing of the electric actuator 7 with bolts or the like. As a result, the positioning bush 20, the front end plate 6A, the two shafts 6C, and the rear end plate 6B are fixed to the housing of the electric actuator 7 as non-driven parts. Therefore, it is possible to fix the non-driven parts of the tool drive device 1 to the workpiece W while the non-driven parts of the tool drive device 1 are positioned on the workpiece W by the positioning bush 20.

[0052] Figure 8 shows an example in which the tool drive device 1 is positioned on the workpiece W using the positioning bush 20 shown in Figure 1.

[0053] The tool drive device 1 can be indirectly positioned and fixed to the workpiece W using a drilling jig J. As a typical example, a drilling plate J2 with a positioning hole J1 can be fixed to the workpiece W after being positioned using a positioning pin J3 or pin bolt using a reference hole in the workpiece W. Then, with a positioning bush 20 inserted into the positioning hole J1 of the drilling plate J2, the flange-shaped part of the positioning bush 20 can be fixed to the drilling plate J2 with a set screw J4. Of course, the positioning bush 20 can also be inserted into a pre-drilled hole in the workpiece W, and the tool drive device 1 can be directly positioned and fixed to the workpiece W.

[0054] When a positioning member 5, such as a positioning bush 20, is fixed directly or indirectly to the workpiece W, the guide 6, to which the positioning member 5 is fixed at its tip, is also fixed to the workpiece W. The guide 6 is a non-powered member provided to move the tool T and spindle 3 relative to the workpiece W and the positioning member 5 in the direction of the rotation axis.

[0055] As illustrated in Figures 1 and 2, if the structure of the guide 6 is such that the front plate 6A and the rear plate 6B are connected by two shafts 6C, the movable plate 22 can be connected to the two shafts 6C by two cylindrical sliders 21 that slide in the longitudinal direction of the shafts 6C, respectively, in contact with the two shafts 6C. The movable plate 22 can then be fixed to the housing 12 of the first electric motor 4.

[0056] This makes it possible to slide the first electric motor 4, the spindle 3 fixed to the output shaft 11 of the first electric motor 4 via an adapter 17, the holder 2 fixed to the spindle 3, and the tool T held by the holder 2 linearly in the longitudinal direction of the shaft 6C, that is, in the feeding direction of the tool T and the spindle 3. In other words, the first electric motor 4, the spindle 3, the holder 2, and the tool T can be moved in the feeding direction relative to the guide 6 fixed to the workpiece W by a positioning member 5 such as a positioning bush 20.

[0057] The electric actuator 7 is a powered device that moves the tool T forward and backward together with the spindle 3 and holder 2 in the feed direction and rotation axis direction relative to the guide 6. The electric actuator 7 consists of a mechanical element for linearly reciprocating the spindle 3 and holder 2, and a second electric motor 23 that powers the mechanical element. In other words, the tool drive device 1 is provided with a first electric motor 4 for rotating the tool T and spindle 3, as well as a second electric motor 23 for moving the tool T and spindle 3 in the feed direction.

[0058] The electric actuator 7 can consist of a second electric motor 23, as well as, for example, a ball screw 24, a pusher 25, a rotor 26, a first pulley 27, a second pulley 28, and a power transmission belt 29, as illustrated in Figures 1 and 2. The first pulley 27 is fixed to the output shaft of the second electric motor 23. The second pulley 28 is fixed to the rotor 26. The power transmission belt 29 is supported by the first pulley 27 and the second pulley 28.

[0059] The rotor 26 has a cylindrical structure and has an internal thread formed on at least a portion of its inner surface. One end of the ball screw 24 protrudes from the housing of the electric actuator 7, and a pusher 25 is fixed to the protruding tip. The other end of the ball screw 24 is inserted into the hollow rotor 26, and the male thread of the ball screw 24 is tightened into the internal thread of the rotor 26.

[0060] In the electric actuator 7 configured in this way, when the second electric motor 23 is activated, the first pulley 27 rotates, and the torque of the first pulley 27 is transmitted to the second pulley 28 via the power transmission belt 29. This reduces the rotational speed and adjusts the torque of the output shaft of the second electric motor 23. When the second pulley 28 rotates, the rotor 26 rotates, and the ball screw 24, which is tightened into the female thread of the rotor 26, moves in the longitudinal direction.

[0061] Therefore, if the longitudinal direction of the ball screw 24 is aligned with the feeding direction of the tool T and spindle 3, the pusher 25 fixed to the tip of the ball screw 24 can be moved forward and backward in the feeding direction of the tool T and spindle 3 according to the rotation direction of the ball screw 24. Consequently, if the pusher 25 is connected to the housing 12 of the first electric motor 4, the tool T and spindle 3 can be moved back and forth in the feeding direction together with the first electric motor 4.

[0062] Furthermore, the reduction gear, which consists of the first pulley 27, the second pulley 28, and the power transmission belt 29, may be made of gears. Alternatively, the second electric motor 23 may rotate a ball screw, and the pusher 25 may be fixed to a member having a female thread that is tightened onto the ball screw, causing it to reciprocate in the feeding direction of the tool T and the spindle 3. In other words, the rotor rotated by the second electric motor 23 may be a ball screw, and the member that moves linearly may have a female thread.

[0063] As a specific example, a ball screw may be fastened inside a cylindrical rod with an internal thread formed on its inner surface, and a pusher 25 may be attached to the tip of the hollow rod, which reciprocates in the feeding direction of the tool T and spindle 3 by the rotation of the ball screw. Alternatively, a bracket with an internal thread may be fastened to the ball screw, and a pusher 25 may be attached to the bracket, which reciprocates in the feeding direction of the tool T and spindle 3 by the rotation of the ball screw.

[0064] When the pusher 25 pushes the first electric motor 4 in the discharge direction, a thrust resistance is applied to the pusher 25. Therefore, from the viewpoint of preventing the generation of unnecessary moments, it is desirable to position the pusher 25 so that its reciprocating path and the rotation axis of the spindle 3 are on the same line. Furthermore, from the viewpoint of ensuring that the electric actuator 7 can sufficiently push the pusher 25 to counteract the thrust resistance, it is desirable to position the pusher 25 so that its reciprocating path is on the same line as the length of the ball screw.

[0065] Therefore, when the stability of the electric actuator 7 is important, it is preferable to configure the electric actuator 7 so that a rod made of a ball screw 24 or a cylindrical rod with an internal thread formed on its inner surface that is tightened to the ball screw reciprocates in the direction of the rotation axis of the spindle 3, and to attach a pusher 25 to the tip of the reciprocating rod.

[0066] On the other hand, by attaching the pusher 25 to a bracket that reciprocates in the direction of the rotation axis of the spindle 3 due to the rotation of the ball screw, the electric actuator 7 can be positioned so that the longitudinal direction of the ball screw 24 and the rotation axis of the spindle 3 are parallel. Therefore, by positioning the electric actuator 7 and the first electric motor 4 adjacent to each other in a direction perpendicular to the rotation axis of the spindle 3, the overall length of the tool drive device 1 can be shortened.

[0067] Furthermore, in addition to the ball screw mentioned above, other mechanical elements that convert the rotational motion generated by the second electric motor 23 into linear motion include rack and pinion gears, and continuous tracks such as power transmission belts that move on pulleys and chains that move on sprockets. Therefore, the electric actuator 7 can be configured by combining these mechanical elements with the second electric motor 23 to move the pusher 25 back and forth.

[0068] As described above, the strength of the housing 12 of the first electric motor 4 is not designed to withstand the localized thrust resistance that is typically applied. Therefore, it is not desirable to press the pusher 25 directly against the housing 12 of the first electric motor 4. Thus, a reinforcing frame 30 can be fixed to the housing 12 of the first electric motor 4, and the pusher 25 can be used to push out the reinforcing frame 30.

[0069] In the examples shown in Figures 1 and 2, as described above, a movable plate 22 that slides along the shaft 6C of the guide 6 is also fixed to the housing 12 of the first electric motor 4. The strength of the movable plate 22 can be designed to withstand thrust resistance. Therefore, the reinforcing frame 30 pushed out by the pusher 25 can be fixed to the movable plate 22. In other words, the reinforcing frame 30 can be fixed indirectly via the movable plate 22 without being directly fixed to the housing 12 of the first electric motor 4.

[0070] Figure 9 is an enlarged left side view of the movable plate 22 and reinforcing frame 30 shown in Figure 1.

[0071] As illustrated in Figures 1, 2, and 9, a movable plate 22, through which the output shaft 11 of the first electric motor 4 passes and which has a through hole in the center for arranging a thrust bearing 16, can be bolted to the front of the housing 12 of the first electric motor 4. For this purpose, the movable plate 22 is provided with a through hole for bolting the movable plate 22 to the housing 12. A slider 21 that slides with the shaft 6C of the guide 6 is also attached to the movable plate 22.

[0072] Furthermore, two rectangular plates longer than the length of the housing 12 can be fixed to the back of the movable plate 22 as part of the reinforcing frame 30 by bolts, welding, etc. In the example shown in Figure 9, stepped through holes are formed in the reinforcing frame 30 so that the two rectangular plates can be fixed to the reinforcing frame 30 with bolts. By connecting the ends of the two rectangular plates with another plate, a reinforcing frame 30 that surrounds the housing 12 can be formed without contacting the housing 12. In addition, the movable plate 22 and the reinforcing frame 30 can be integrated.

[0073] This allows the first electric motor 4 to be pushed in the outward direction by applying force from the pusher 25 to the reinforcing frame 30. In other words, the electric actuator 7 can move the reinforcing frame 30 relative to the guide 6. Furthermore, the thrust resistance transmitted from the thrust bearing 16 to the housing 12 is transmitted from the housing 12 to the moving plate 22, and then from the moving plate 22 to the reinforcing frame 30.

[0074] Therefore, a load cell 32 can be attached to the reinforcing frame 30 as a sensor 31 for measuring cutting resistance, and force can be applied to the load cell 32 from the pusher 25. In other words, a load cell 32 for measuring the thrust resistance transmitted from the spindle 3 can be connected to the rear end of the spindle 3 via an adapter 17, a thrust bearing 16, a base 18, the housing 12 of the first electric motor 4, a movable plate 22, and a reinforcing frame 30.

[0075] Therefore, the load cell 32 measures the thrust resistance transmitted from the spindle 3 to the housing 12 via the thrust bearing 16 and base 18, and further transmitted from the housing 12 to the reinforcing frame 30 integrated with the movable plate 22. Furthermore, from the viewpoint of enabling more accurate measurement of thrust resistance with the load cell 32, it is appropriate to determine the mounting position of the load cell 32 such that the center position of the load cell 32 and the rotation axis of the spindle 3 are on the same straight line. In addition, it is appropriate to make the shape of the reinforcing frame 30 symmetrical with respect to the rotation axis of the spindle 3 in a cross-section including the rotation axis of the spindle 3.

[0076] By measuring the thrust resistance with the load cell 32, it becomes possible to control the tool drive device 1 according to the thrust resistance. As described above, the tool drive device 1 is equipped with a first electric motor 4 for rotating the tool T and spindle 3, as well as a second electric motor 23 for moving the tool T and spindle 3 in the feed direction, and the rotational speed and feed speed of the tool T and spindle 3 can be set independently of each other. Therefore, the rotational speed and feed speed of the tool T and spindle 3 can be automatically controlled based on the thrust resistance measured by the load cell 32.

[0077] Therefore, the thrust resistance measured by the load cell 32 is output to the controller 8. The controller 8 is an electrical circuit such as a computer that outputs electrical signals to control the first electric motor 4 and the second electric motor 23.

[0078] In order to measure thrust resistance with the load cell 32, it is necessary to bring the pusher 25 into contact with the load cell 32 so that thrust resistance is applied to the pusher 25. However, if the pusher 25 is in constant contact with the load cell 32, a load will be detected by the load cell 32 even when no holes have been drilled and no thrust resistance is generated.

[0079] For example, if the load cell 32 is fixed by being sandwiched between the reinforcing frame 30 and the pusher 25, the load cell 32 will constantly be subjected to a load from the pusher 25, so the load detected by the load cell 32 will not always be zero. Also, if the load cell 32 comes into contact with the pusher 25 when the tool T and spindle 3 are being retracted after the hole drilling is complete, the load applied to the spindle 3 from the electric actuator 7 to retract the tool T and spindle 3 will be detected by the load cell 32.

[0080] In that case, the controller 8 would need to perform data processing to distinguish the load detected by the load cell 32 from thrust resistance and other loads. In addition, since the load detected by the load cell 32 is not always zero, calibration may be necessary to ensure good accuracy in measuring thrust resistance.

[0081] Therefore, as illustrated in Figures 1 and 2, the relative positions of the pusher 25 and the load cell 32 can be determined such that a gap is created between the pusher 25 and the load cell 32 when the pusher 25 is retracted to its retracted position, and the pusher 25 and the reinforcing frame 30 to which the load cell 32 is attached can be connected via a sliding mechanism 33. More specifically, the pusher 25 can be connected to the load cell 32 and the spindle 3 by a sliding mechanism 33 that changes the distance between the pusher 25 and the load cell 32 in the direction of the rotation axis of the spindle 3.

[0082] Figure 10 is an enlarged view of the pusher 25, load cell 32, and slide mechanism 33 shown in Figure 2.

[0083] As illustrated in Figures 1, 2, and 10, the slide mechanism 33 can be composed of, for example, two shafts 33B with a disc-shaped stopper 33A fixed to one end, and two cylindrical sliders 33C that slide against the two shafts 33B, respectively. The two shafts 33B are arranged parallel to each other so that their longitudinal direction is parallel to the rotation axis direction of the spindle 3.

[0084] In the illustrated example, two sliders 33C are fixed to the reinforcing frame 30 at positions that sandwich the load cell 32, and the other ends of the two shafts 33B, on the side where the stopper 33A is not attached, are fixed via a fixing plate 34 near the tip of the ball screw 24 to which the pusher 25 is attached. As a result, the distance between the pusher 25 and the load cell 32 can be freely changed by the sliding mechanism 33 without the need for power.

[0085] Alternatively, the slider 33C may be fixed to a fixing plate 34 attached near the tip of the ball screw 24, and the end of the shaft 33B on the side without the stopper 33A may be fixed to the reinforcing frame 30. In other words, the slide mechanism 33 consisting of the stopper 33A, shaft 33B, and slider 33C may be reversed in the sliding direction of the slide mechanism 33.

[0086] When the pusher 25 and the load cell 32 are connected via the sliding mechanism 33 in the orientation shown in the diagram, when the pusher 25 is moved forward from the retracted position by the electric actuator 7, the fixing plate 34, shaft 33B, and stopper 33A slide together with the pusher 25 in the forward direction relative to the reinforcing frame 30 to which the load cell 32 is attached, causing the pusher 25 to come into contact with the load cell 32.

[0087] Therefore, when the electric actuator 7 moves the pusher 25 further forward, a force acts on the spindle 3 from the pusher 25 via the load cell 32 and the reinforcing frame 30 in the direction of the spindle 3's forward movement. This allows the tool T to be moved forward together with the spindle 3.

[0088] As long as the pusher 25 is in contact with the load cell 32 and force is acting from the pusher 25 to the load cell 32, the load is measured by the load cell 32. Therefore, even before drilling begins, if the spindle 3 is advanced, a load is detected by the load cell 32. Then, when drilling begins and thrust resistance is generated, a load that can be considered as thrust resistance is detected by the load cell 32.

[0089] On the other hand, once the hole drilling is complete, the pusher 25 is retracted by the electric actuator 7 to move the tool T and spindle 3 back. Along with the pusher 25, the fixing plate 34, shaft 33B, and stopper 33A slide in the direction of the pusher 25's retraction relative to the reinforcing frame 30 to which the load cell 32 is attached. As a result, the pusher 25 is pulled away from the load cell 32. Consequently, the load detected by the load cell 32 becomes zero.

[0090] When the electric actuator 7 moves the pusher 25 further back, the disc-shaped stopper 33A of the slide mechanism 33 comes into contact with the slider 33C fixed to the reinforcing frame 30, and a force acts on the reinforcing frame 30 from the stopper 33A in the direction of the pusher 25's retraction. As a result, the spindle 3 retracts together with the reinforcing frame 30 to which the load cell 32 is attached, with the pusher 25 separated from the load cell 32.

[0091] In this way, the load cell 32 can detect a load while the spindle 3 is moving forward, while the load cell 32 can not detect a load while the spindle 3 is moving backward. This makes it possible to accurately measure thrust resistance without setting the zero point of the load cell 32 or performing calibration.

[0092] Furthermore, the pusher 25, which is moved forward and backward by the electric actuator 7, slides relative to the load cell 32 when it starts moving forward from the pusher 25's retracted position (the position where the pusher 25 is moved furthest back), when it starts moving backward, and when it switches the direction of travel of the pusher 25 while it is moving backward to move forward. As a result, a time lag occurs between the forward and backward movements of the electric actuator 7 and the forward and backward movements of the spindle 3. Therefore, to prevent this time lag from becoming too long to adversely affect the hole machining, it is appropriate to set the sliding range (stroke) of the sliding mechanism 33, that is, the maximum value of the gap formed between the load cell 32 and the pusher 25, to about 1 mm to 3 mm.

[0093] Furthermore, since the reinforcing frame 30 equipped with the slider 33C can slide freely along the shaft 33B, it is appropriate to provide a stopper 35 to prevent the load cell 32 from retracting so that it does not come into contact with the pusher 25 due to inertia after the pusher 25 has retracted and stopped in the retracted position. In other words, it is appropriate to provide a stopper 35 so that when the reinforcing frame 30 to which the load cell 32 is attached and the spindle 3 are retracted, they stop in the retracted position.

[0094] The stopper 35 for preventing the load cell 32 and spindle 3 from retracting to the retracted position can be fixed, for example, as a disc-shaped member that contacts the slider 21 to the shaft 6C of the guide 6 for sliding the movable plate 22 which is integrated with the reinforcing frame 30, as illustrated in Figures 1 and 2. Of course, a bar that contacts the reinforcing frame 30 may also be fixed to the shaft 6C of the guide 6 as the stopper 35. It is also appropriate to provide a stopper 35 for preventing the load cell 32 and spindle 3 from retracting even when the configuration of the slide mechanism 33 is reversed in the sliding direction.

[0095] The load cell 32 may be fixed to the drive unit of the electric actuator 7, such as the ball screw 24, instead of the reinforcing frame 30. In that case, the load cell 32 will reciprocate on the electric actuator 7 instead of the pusher 25. However, from the viewpoint of avoiding adverse effects on the measurement accuracy of thrust resistance due to the deflection of the drive unit of the electric actuator 7, it is desirable to fix the load cell 32 to the highly rigid reinforcing frame 30.

[0096] By measuring the thrust resistance with the load cell 32, the controller 8 can control the first electric motor 4 and electric actuator 7 based on the thrust resistance so that the rotational speed and feed rate of the tool T and spindle 3 correspond to the rotational speed and feed rate measured by the load cell 32.

[0097] Figure 11 shows a detailed configuration example of the controller 8 shown in Figure 1.

[0098] The controller 8 can be configured as an electrical circuit in which necessary electrical equipment such as an A / D (analog-to-digital) converter is connected to an electronic circuit such as a computer equipped with an input device 40, a storage device 41, a display 42, and an arithmetic unit 43. The control program of the tool drive device 1 is loaded into the arithmetic unit 43, and the arithmetic unit 43 can function as a machining condition setting unit 44, a rotation / feed rate control unit 45, a thrust resistance recording / output unit 46, an anomaly detection unit 47, and a timer 48, while the storage device 41 can function as a machining condition database 49.

[0099] The processing condition setting unit 44 has the function of setting appropriate hole processing conditions for each material that may be subject to hole processing based on information input from an input device 40 such as a mouse or keyboard, and saving the set hole processing conditions in the processing condition database 49. For this purpose, the hole processing condition setting screen can be displayed on the display 42. The hole processing condition setting screen can be part of the operation screen of the controller 8.

[0100] Figure 12 shows an example of the operation screen displayed on the display 20 of the controller 8 shown in Figure 11, and Figure 13 illustrates the starting position of the approach movement and the starting position of the retraction movement of the tool T, which can be set through the operation screen shown in Figure 12.

[0101] The hole machining conditions can be expressed in terms of the rotational speed (rpm) of the tool T and spindle 3, and the feed rate (mm / min). The feed rate of the tool T and spindle 3 may also be expressed as the feed amount per revolution (mm / revolution).

[0102] The appropriate hole drilling conditions vary depending on the material, such as metals like aluminum and titanium, and fiber-reinforced plastics (FRP) like glass fiber reinforced plastics (GFRP) and carbon fiber reinforced plastics (CFRP).

[0103] Therefore, as illustrated in Figure 12, appropriate hole machining conditions can be set for each material. Note that there are various types of hole machining, including drilling into a workpiece W without a pre-drilled hole, finishing or enlarging a pre-drilled hole in the workpiece W, and final finishing of a hole with a reamer. Appropriate hole machining conditions vary depending on the characteristics of the tool T, including its material, diameter, number of teeth, and shank thickness and length, as well as the type of hole machining, such as whether or not a pre-drilled hole is present. Therefore, it is appropriate to set appropriate hole machining conditions for each characteristic of the tool T and the type of hole machining.

[0104] Similar to the hole drilling conditions, the thrust resistance generated during hole drilling also differs depending on the characteristics of the tool T, the type of hole drilling, and the material. Therefore, the hole drilling conditions can be set in association with the thrust resistance in the machining condition setting unit 44 and saved in the machining condition database 49. This makes it possible to identify the material to be drilled based on the thrust resistance measured by the load cell 32 and automatically set appropriate hole drilling conditions for the identified material.

[0105] Furthermore, it is difficult to simultaneously and instantaneously change the rotational speed and feed rate of the tool T to match the material identified by detecting thrust resistance, and this is also inappropriate from the standpoint of maintaining hole quality. Therefore, a delay time, or time lag, can be set as part of the hole machining conditions, from the initial detection of thrust resistance associated with the material to the change in the rotational speed and feed rate of the tool T to match the material.

[0106] When the rotational speed and feed rate of the tool T are changed in accordance with the thrust resistance measured by the load cell 32, the thrust resistance will also change according to the rotational speed and feed rate of the tool T after the change. Therefore, it is appropriate to set the thrust resistance, which is associated with the hole drilling conditions in order to identify the material, as a range of values ​​that can be taken for each material.

[0107] Furthermore, if the rotational speed and feed rate of tool T are changed to match the material, the thrust resistance may change significantly, or as a result of the change in thrust resistance, the range of thrust resistance that can be taken between different materials may overlap. In such cases, it may be possible to set separately the range of thrust resistance values ​​for identifying the material and the range of thrust resistance values ​​after changing the rotational speed and feed rate of tool T to match the material.

[0108] When the rotational speed and feed rate of tool T are optimal for the material, the thrust resistance value will also be optimal. Therefore, the control that optimizes the rotational speed and feed rate of tool T according to the thrust resistance measured by load cell 32 can be said to be a feedback control that optimizes the thrust resistance measured by load cell 32.

[0109] In addition to the rotational speed and feed rate of the tool T, the machining condition setting unit 44 also allows setting the starting position of the approach movement from when the tool T approaches the workpiece W until it makes contact, as shown in Figure 13, and the starting position of the retraction movement of the tool T after hole machining. In other words, the approach movement can be performed so that the tool T does not collide with the workpiece W at an insufficient rotational speed. In this case, a safe rotational speed and feed rate for the approach movement of the tool T and spindle 3 are set. Furthermore, if the tool T and spindle 3 are to be retracted without advancing to the maximum stroke, the starting position of the retraction movement of the tool T can be set.

[0110] The starting position of the approach movement can be determined by the distance from the position of the tip of the tool T in the retracted position to the starting position of the approach movement. Therefore, in addition to the protrusion length of the tool T from the holder 2, if the holder 2 can be replaced, the distance from the position of the tip of the tool T in the retracted position to the starting position of the approach movement can be set according to the length of the holder 2.

[0111] Once the starting position for the approach movement is set, the tool T and spindle 3 can be rapidly advanced to the starting position of the approach movement, regardless of the load detected by the load cell 32. Furthermore, during rapid traverse of the tool T, it is possible to either stop the rotation of the tool T or gradually increase the rotational speed of the tool T to the desired rotational speed during rapid traverse.

[0112] On the other hand, the starting position of the tool T's retraction can be set as follows: when machining a hole that does not penetrate the workpiece W, it is the distance from the tip of the tool T in the retracted position to the maximum depth of the hole; when machining a through hole in the workpiece W, it is the distance corresponding to the thickness of the workpiece W so that the cutting edge of the tool T completely passes through the workpiece W. Setting the starting position of the tool T's retraction corresponds to setting the stroke of the tool T and the spindle 3 to less than the maximum stroke.

[0113] Furthermore, when machining a through hole in a workpiece W, the thrust resistance gradually decreases to zero as the tip of the tool T penetrates the workpiece W. However, the rotational speed and feed rate of the tool T should not be reduced until the tool T's maximum diameter position has completely passed through the workpiece W. Therefore, if the load detected by the load cell 32 decreases to outside the range of thrust resistance values ​​associated with the material, it is appropriate to set control conditions so that the rotational speed and feed rate of the tool T and spindle 3 are not changed until the tool T reaches the starting position of its retraction or the maximum stroke position.

[0114] Setting the starting position of the tool T's retraction movement in this way not only facilitates the machining of non-through holes with a desired depth, but also eliminates the need to detect the time when the hole machining is completed based on the load detected by the load cell 32, or to detect when the tool T's maximum diameter position has completely passed the workpiece W, when machining through holes without advancing the tool T and spindle 3 to the allowable range. Furthermore, it facilitates the machining of holes in overlapping materials with gaps between them.

[0115] Furthermore, the retraction movement of tool T can also be performed at a rapid traverse, similar to the forward movement of tool T from its retracted position to the start of its approach movement. In other words, tool T can be retracted at a rapid traverse from the start of its retraction movement to its retracted position.

[0116] The rotation / feed rate control unit 45 has the function of controlling the tool drive device 1 based on the load detected by the load cell 32 by referring to the machining condition database 49. Specifically, the rotation / feed rate control unit 45 has the function of acquiring the load detected by the load cell 32 and, if the load detected by the load cell 32 falls within the range of thrust resistance values ​​associated with the hole machining conditions, outputting control signals to the first electric motor 4 and the second electric motor 23 of the electric actuator 7 so that hole machining is performed at the rotation speed and feed rate of the tool T associated with the range of thrust resistance values.

[0117] As described above, when the pusher 25 that presses against the load cell 32 is in the retracted position, a gap is created between the load cell 32 and the pusher 25, so the load detected by the load cell 32 becomes zero. For this reason, although signal processing such as noise reduction processing may be performed on the detection signal from the load cell 32, it is unnecessary to extract the thrust resistance component from the load detected by the load cell 32, and the load detected by the load cell 32 can be considered as thrust resistance.

[0118] Furthermore, while the rotation / feed rate control unit 45 does not necessarily need to perform processing to identify and output the material being processed, as mentioned above, since the range of thrust resistance values ​​is associated with the material, the rotation / feed rate control unit 45 effectively identifies the material based on the measured thrust resistance and automatically sets appropriate hole machining conditions for the identified material. This automatic setting of hole machining conditions allows the rotation speed and feed rate of the tool T and spindle 3 to be automatically switched to the rotation speed and feed rate corresponding to the thrust resistance measured in real time by the load cell 32, with a predetermined delay time.

[0119] The delay time can be generated using the timer 48. Specifically, after the delay time set by the timer 48, the rotation / feed rate control unit 45 outputs control signals to the first electric motor 4 and the second electric motor 23 to change the rotation speed and feed rate of the tool T and spindle 3.

[0120] When machining holes in a stacked material made of different materials, the thrust resistance changes when the tool T reaches the boundary between the materials, and the rotation / feed rate control unit 45 can substantially detect that the material being cut has changed. Therefore, unlike the settings for the stroke of the tool T and spindle 3, it is not necessary to pre-set the thickness of each material as a hole machining condition.

[0121] Furthermore, the rotation / feed rate control unit 45 has the function of controlling the tool drive device 1 in manual mode, in which the rotation speed and feed rate of the tool T and spindle 3 are directly set according to instruction information such as numerical values ​​input from the input device 40. In addition, it also has the function of outputting control signals to the first electric motor 4 and the second electric motor 23 of the electric actuator 7 so that the tool T approaches the workpiece W under conditions stored in the machining condition database 49, and the retraction of the tool T starts at the starting position of the tool T's retraction operation stored in the machining condition database 49.

[0122] Therefore, after setting the tool drive device 1 on the workpiece W, if the input device 40 gives an instruction to the rotation / feed rate control unit 45 to start hole machining in automatic mode, for example by pressing the start button displayed as an electronic key on the operation screen, the hole machining of the workpiece W can be completed fully automatically.

[0123] The thrust resistance recording / output unit 46 has the function of displaying the load measured by the load cell 32 in real time on the operation screen of the display 42, and the function of recording the thrust resistance measured by the load cell 32 and saving it to the machining condition database 49.

[0124] By displaying the load measured by the load cell 32, the user can check the material being drilled. Furthermore, if the thrust resistance increases abnormally due to wear of the tool T or chipping of the cutting edge of the tool T, the user can quickly detect this and interrupt the drilling process by pressing the stop button displayed on the operation screen using the input device 40, if necessary.

[0125] On the other hand, by recording the thrust resistance measured by the load cell 32 and saving it in the machining condition database 49 in association with the material, it becomes possible to set hole machining conditions associated with the thrust resistance for unregistered materials. This is true not only for materials, but also when the characteristics of the tool T or other hole machining conditions change. Furthermore, even for hole machining conditions already registered in the machining condition database 49, accumulating thrust resistance measurements makes it possible to set more appropriate hole machining conditions using machine learning or the like.

[0126] The abnormality detection unit 47 has the function of detecting abnormalities such as wear and chipping of the tool T based on the load measured by the load cell 32, and when an abnormality of the tool T is detected, it has the function of notifying the user of the detected abnormality through the display 42. Of course, the abnormality may be notified to the user by sound or light through output devices such as speakers or lights, rather than being limited to the display 42.

[0127] Abnormalities in the tool T can be detected by threshold processing, which involves setting a threshold to define an acceptable range for the thrust resistance value and determining whether the thrust resistance value measured by the load cell 32 is within the acceptable range. Alternatively, a threshold can be set to define an even more acceptable range for periods during which thrust resistance values ​​outside the acceptable range are continuously measured by the load cell 32. For example, if thrust resistance values ​​outside the acceptable range are continuously measured by the load cell 32 for several seconds, the abnormality detection unit 47 may determine that an abnormality has occurred in the tool T.

[0128] (Method of manufacturing perforated products) Next, we will explain a method for manufacturing a drilled product by drilling holes in a workpiece W using a tool drive device 1.

[0129] When drilling holes in a workpiece W using the tool drive device 1, the thrust resistance generated when drilling holes at appropriate rotational speeds and feed rates for each material that can make up the workpiece W is measured in advance. The thrust resistance can be obtained as the load measured by the load cell 32 when drilling holes in a test piece with the tool drive device 1 and manually adjusting the rotational speed and feed rate of the tool T to appropriate values.

[0130] The thrust resistance measured by the load cell 32 is output to the controller 8, and the thrust resistance recording / output unit 46 displays the thrust resistance on the display 42 while saving it as time-series measurement data in the machining condition database 49. This makes it possible to determine the thrust resistance when the rotational speed and feed rate of the tool T are at appropriate values.

[0131] Once the appropriate thrust resistance is determined, the following machining conditions that affect the thrust resistance are associated with the thrust resistance and stored in the machining condition database 49 as hole machining conditions: tool T identification information associated with the characteristics of the tool T, material identification information, appropriate tool T rotation speed and feed rate, a delay time of a few seconds from when the tool T contacts the material until the appropriate tool T rotation speed and feed rate is changed, and the presence or absence of a pre-drilled hole.

[0132] The setting and saving of hole machining conditions can be performed by operating the input device 40 through an operation screen, as illustrated in Figure 12, displayed on the display 42 by the machining condition setting unit 44. Specifically, the machining condition setting unit 44 sets the hole machining conditions based on the information input from the input device 40 and saves the set hole machining conditions in the machining condition database 49. Once the setting and saving of the hole machining conditions is complete, it becomes possible to perform hole machining on the workpiece W using the saved hole machining conditions.

[0133] When drilling holes in the workpiece W is to begin, the tool drive unit 1 is positioned and installed on the workpiece W. Specifically, as illustrated in Figure 8, the positioning bush 20 of the tool drive unit 1 is inserted into the positioning hole J1 of the drilling plate J2 fixed to the workpiece W, and the flange-shaped portion of the positioning bush 20 can be fixed to the drilling plate J2 with a set screw J4.

[0134] Meanwhile, the starting position of the tool T's approach movement and the starting position of its retraction movement, as shown in Figure 13, are set via the operation screen displayed on the display 42, along with the rotational speed and feed rate during the tool T's approach movement. Specifically, the machining condition setting unit 44 sets the starting position of the tool T's approach movement, the starting position of its retraction movement, and the rotational speed and feed rate during the tool T's approach movement as hole machining conditions for each workpiece W, based on the information input from the input device 40, and saves the set hole machining conditions in the machining condition database 49.

[0135] Furthermore, if the distance from the initial position of tool T to the workpiece W is short, the approach operation may be performed from the initial position of tool T without setting a starting position for the approach operation. In this case, the rotational speed and feed rate during the approach operation are set as the initial values ​​for the rotational speed and feed rate of tool T. Also, if tool T is advanced to the maximum stroke of the tool drive unit 1 and then retracted, the setting of the starting position for the retraction operation can be omitted.

[0136] Then, when the user inputs information from the input device 40 to the rotation / feed speed control unit 45 to instruct the start of hole drilling, such as by pressing the start button on the operation screen, the rotation / feed speed control unit 45 controls the tool drive unit 1 according to the hole drilling conditions stored in the machining condition database 49. This starts the operation of the tool drive unit 1.

[0137] Specifically, the rotation / feed rate control unit 45 outputs a control signal to the second electric motor 23 of the electric actuator 7 so that the tool T and spindle 3 move forward at rapid traverse from the retracted position to the starting position of the approach movement. As a result, the second electric motor 23 rotates, and the ball screw 24 of the electric actuator 7 moves forward at a speed corresponding to the rapid traverse.

[0138] As a result, the slide mechanism 33 connected to the ball screw 24 slides, and the pusher 25 fixed to the tip of the ball screw 24 presses against the load cell 32. This causes the moving plate 22, together with the reinforcing frame 30 to which the load cell 32 is attached, to move forward along the shaft 6C of the guide 6. Consequently, the first electric motor 4, to which the housing 12 is fixed, the spindle 3 connected to the first electric motor 4, the holder 2, and the tool T move forward at rapid traverse.

[0139] Next, the rotation / feed rate control unit 45 outputs control signals to the first electric motor 4 and the second electric motor 23 of the electric actuator 7 so that the tool T and spindle 3 approach the workpiece W from the starting position of the approach movement at the specified rotational speed and feed rate. As a result, the output shaft 11 of the first electric motor 4 rotates, and the holder 2 and tool T rotate at the specified rotational speed together with the spindle 3 connected to the output shaft 11 via the adapter 17. On the other hand, the second electric motor 23 decelerates, and the forward speed of the ball screw 24 to which the pusher 25 is attached becomes the specified feed rate. As a result, the forward speeds of the first electric motor 4, spindle 3, holder 2 and tool T also become the specified feed rate.

[0140] When the tool T moves forward and makes contact with the workpiece W, cutting begins, while cutting resistance is applied from the workpiece W to the tool T. This cutting resistance is transmitted from the tool T to the spindle 3 via the holder 2. Of the cutting resistance transmitted to the spindle 3, the cutting torque is transmitted from the spindle 3 to the output shaft 11 of the first electric motor 4 via the adapter 17.

[0141] In contrast, the thrust resistance of the cutting resistance transmitted to the spindle 3 is not transmitted to the output shaft 11, but to the thrust bearing 16. This is because, as shown in Figure 6, a gap 19A is provided between the support surface perpendicular to the thrust direction formed on the flange 17A of the adapter 17 and the end face of the output shaft 11 to suppress the transmission of thrust resistance, and the support surface perpendicular to the thrust direction formed on the flange 17A of the adapter 17 is in contact only with the thrust bearing 16. This prevents the output shaft 11 of the first electric motor 4 from being subjected to excessive thrust resistance, which would cause the output shaft 11 to become eccentric and reduce the quality and accuracy of the hole.

[0142] The thrust resistance transmitted to the thrust bearing 16 is transmitted to the housing 12 of the first electric motor 4. However, the area of ​​the surface perpendicular to the thrust direction of the thrust bearing 16 is determined so that the housing 12 can withstand the thrust resistance, and therefore the housing 12 will not deform or break.

[0143] The thrust resistance transmitted to the housing 12 is transmitted via the movable plate 22 and the reinforcing frame 30 to the load cell 32, which is pushed out by a force from the pusher 25 that counteracts the thrust resistance. This allows the thrust resistance to be measured by the load cell 32.

[0144] Furthermore, when measuring thrust resistance in advance using a test piece, the thrust resistance transmitted through a similar path can be measured by the load cell 32. Also, before the pusher 25 moves forward, no force is acting from the pusher 25 to the load cell 32, and no load is detected by the load cell 32. Therefore, the load measured by the load cell 32 can be treated directly as the thrust resistance.

[0145] The thrust resistance measured by the load cell 32 is output to the controller 8. In the controller 8, the rotation / feed rate control unit 45 constantly monitors the load measured by the load cell 32, and the rotation / feed rate control unit 45 refers to the machining condition database 49 to substantially identify the material associated with the thrust resistance output from the load cell 32. The first electric motor 4 and the second electric motor 23 are then controlled by the rotation / feed rate control unit 45 so that hole machining is performed on the workpiece W under the hole machining conditions associated with the thrust resistance.

[0146] Specifically, from the time of the initial detection of thrust resistance that led to the identification of the material, a delay of several seconds specified as a hole-making condition is followed by a control signal output from the rotation / feed rate control unit 45 to the first electric motor 4 and the second electric motor 23, so that the tool T and spindle 3 rotate and advance at the rotation speed and feed rate set as a hole-making condition.

[0147] Therefore, after the tool T contacts the workpiece W and thrust resistance is detected, the rotational speed and feed rate are safely accelerated and decelerated over a period of several seconds. As a result, the rotational speed and feed rate of the tool T and spindle 3 become the appropriate rotational speed and feed rate for each material set as the hole machining conditions. Consequently, the thrust resistance value also corresponds to the appropriate rotational speed and feed rate. This allows for hole machining of the workpiece W under favorable cutting conditions.

[0148] If the workpiece W is a composite material of different materials, the thrust resistance changes when the tool T contacts the adjacent material in the depth direction of the hole. When the changed thrust resistance is detected by the load cell 32 and output to the controller 8, the rotation / feed rate control unit 45 refers to the machining condition database 49 to substantially identify the material associated with the changed thrust resistance. Then, the first electric motor 4 and the second electric motor 23 are controlled by the rotation / feed rate control unit 45 according to the hole machining conditions associated with the identified material. This allows hole machining to be performed on adjacent materials at appropriate rotation and feed rates.

[0149] The thrust resistance measured by the load cell 32 is displayed in real time on the display 42 by the thrust resistance recording / output unit 46, while also being stored in the machining condition database 49. This allows the user to check the change in thrust resistance over time and understand which material is being machined. In addition, if any abnormalities are found or if a problem is discovered afterward, the user can check the change in thrust resistance over time stored in the machining condition database 49 to confirm whether the cutting conditions were appropriate.

[0150] The thrust resistance measured by the load cell 32 is also monitored by the anomaly detection unit 47 to ensure it does not show an abnormal value. That is, if the anomaly detection unit 47 detects an abnormality in the thrust resistance, it notifies the user of the anomaly through the display 42 or the like. Therefore, even if the user overlooks the abnormal thrust resistance displayed on the display 42, it is still possible to detect anomalies such as tool wear or chipping.

[0151] When the tool T penetrates the workpiece W, thrust resistance is eliminated, and the load cell 32 only detects the load from the pusher 25 that advances the tool T and spindle 3. However, if the load measured by the load cell 32 decreases to a negligible level as a hole machining condition, the rotational speed and feed rate of the tool T and spindle 3 are set not to change, allowing the tool T to be advanced to the starting position of the retraction movement without changing the rotational speed and feed rate.

[0152] When the rotation / feed speed control unit 45 detects that the tool T has reached the starting position of the retraction movement based on the control amounts of the electric actuator 7 and the second electric motor 23, it controls the first electric motor 4 and the second electric motor 23 so that the tool T retracts rapidly from the starting position of the retraction movement to the retracted position. As a result, the pusher 25 retracts together with the ball screw 24, and the slide mechanism 33 connected to the ball screw 24 slides. Consequently, the pusher 25 is pulled away from the load cell 32, and the load detected by the load cell 32 becomes zero.

[0153] Further retraction of the ball screw 24 causes the slide mechanism 33 to slide to its maximum stroke position, and the movable plate 22, along with the reinforcing frame 30 connected to the slide mechanism 33, moves backward along the shaft 6C of the guide 6. As a result, the first electric motor 4, to which the housing 12 is fixed, the spindle 3 connected to the first electric motor 4, the holder 2, and the tool T move backward at rapid traverse.

[0154] When the ball screw 24 retracts to its retracted position, the ball screw 24 is stopped by the electronic control of the second electric motor 23. Meanwhile, the first electric motor 4, the spindle 3 connected to the first electric motor 4, the holder 2, and the tool T, whose housing 12 is fixed to the moving plate 22, are physically stopped when the slider 21 attached to the moving plate 22 comes into contact with the stopper 35. This creates a gap between the load cell 32 and the pusher 25, which are attached to the moving plate 22 via the reinforcing frame 30, thus preventing the load from being detected by the load cell 32 before it moves forward.

[0155] When the hole machining of the workpiece W is completed, a hole-machined product is obtained as a finished or semi-finished product. The hole-machined product is machined by a tool T that rotates with torque applied from the output shaft 11 of the first electric motor 4, in which the eccentricity of the central axis is suppressed by the provision of a thrust bearing 16, and is machined by a tool T that rotates and feeds at an appropriate rotational speed and feed rate based on the thrust resistance measured by a load cell 32, thus ensuring high quality.

[0156] (effect) In the tool drive device 1 and the method for manufacturing drilled products described above, the rotation of the spindle 3 is performed by the first electric motor 4, while the feeding operation of the spindle 3 is performed by an electric actuator 7 driven by the second electric motor 23, and the appropriate rotation speed and feed speed of the spindle 3 can be automatically set based on the thrust resistance measured by the load cell 32.

[0157] Therefore, according to the tool drive device 1 and the method for manufacturing drilled products, if appropriate drilling conditions are saved in advance in the drilling condition database 49 of the controller 8, the user does not need to set the rotational speed and feed rate of the tool T each time drilling is performed, and drilling can be performed with appropriate drilling conditions even if the user is not familiar with the drilling conditions. In addition, even when drilling holes in laminated materials made by stacking different materials, the rotational speed and feed rate of the spindle 3 are automatically updated appropriately for each material in response to changes in thrust resistance, so that the user can complete drilling without having to consider the thickness of each material or the drilling conditions for each material.

[0158] Furthermore, the rotational speed and feed rate of spindle 3 can be automatically set by the controller 8 based on a single parameter, thrust resistance, without the need for complex processing such as prediction. Therefore, the rotational speed and feed rate of spindle 3 can be automatically controlled with extremely simple data processing.

[0159] Conversely, by attaching only the load cell 32 as the sensor 31 to the tool drive device 1, the rotational speed and feed rate of the spindle 3 can be automatically controlled. Therefore, unlike machine tools such as machining centers that use a very large number of sensors to perform complex control such as feedforward control, the possibility of malfunctions due to sensor failure or accumulation of measurement errors is low.

[0160] In particular, by making the load cell 32 slidable using the sliding mechanism 33, the zero point setting of the load cell 32 can be performed mechanically without relying on data processing in the controller 8. Therefore, calibration of the load cell 32 and other related tasks become unnecessary.

[0161] (Other embodiments) Although specific embodiments have been described above, these embodiments are merely examples and do not limit the scope of the invention. The novel methods and apparatus described herein can be embodied in various other forms. Furthermore, various omissions, substitutions, and modifications can be made in the forms of methods and apparatus described herein, without departing from the spirit of the invention. The attached claims and equivalents include such various forms and modifications as being encompassed within the scope and spirit of the invention.

[0162] For example, the tool drive device 1 may be equipped with a function to supply cutting fluid such as lubricating oil or coolant, or a function to circulate air for dust collection or cooling. The cutting fluid may also be sprayed in the form of a mist. In that case, an adapter for connecting a hose that forms a passage for the cutting fluid or air may be attached to the holder 2.

[0163] Furthermore, the coreless motor 10, which is equipped with a thrust bearing 16 to withstand thrust resistance, and the first electric motor 4, which has a core, can also be used for machining other than hole drilling. For this reason, although the above example was described using the case where the tool drive device 1 is a device for hole drilling, the tool drive device may also be a device for cutting processes such as milling, which is carried and used by the user by hand.

[0164] In that case, in addition to the rotation axis direction of the spindle 3, the necessary drive shafts can be added to the electric actuator 7 so that the spindle 3 and the first electric motor 4 can be moved relative to the guide 6 in a direction perpendicular to the rotation axis direction of the spindle 3, for example, in the orthogonal 3-axis direction. Of course, a rotation axis can also be added to the electric actuator 7 so that the rotation axis direction and the feed direction of the spindle 3 can be tilted.

[0165] Then, by holding a cutting tool T, such as an end mill, in the holder 2 and performing cutting on the workpiece W, a machined product can be manufactured. The machined product manufactured in this way is of high quality because it is cut by a tool T that rotates due to torque applied from the output shaft 11 of the first electric motor 4, whose central axis eccentricity is suppressed by the provision of a thrust bearing 16.

[0166] Furthermore, although the above-described embodiment described a case in which a load cell 32 for measuring thrust resistance is used as the sensor 31 for measuring cutting resistance, a torque sensor for measuring cutting torque may be used instead of the load cell 32, or in addition to the load cell 32. The torque sensor can be connected to a desired position on the rotating part integrated with the spindle 3.

[0167] If only the torque sensor is used instead of the load cell 32, the rotational speed and feed rate of the spindle 3 can be automatically set with simple data processing based on a single parameter, the cutting torque, similar to the case where the rotational speed and feed rate of the spindle 3 are automatically set based only on thrust resistance. However, if thrust resistance is measured with the load cell 32, as described above, the slide mechanism 33 can be used to prevent mechanical load from being placed on the load cell 32 when the spindle 3 retracts, thus further simplifying data processing in the controller 8. [Explanation of symbols]

[0168] 1...Tool drive unit, 2...Holder, 3...Spindle, 4...First electric motor, 5...Positioning member, 6...Guide, 6A...Front end plate, 6B...Rear end plate, 6C...Shaft, 7...Electric actuator, 8...Controller, 9...Gear, 10...Coreless motor, 11...Output shaft, 12...Housing, 13...Rotor, 14...Stator, 15...Rotating shaft, 16...Thrust bearing, 16A...Thrust washer, 16B...Roller, 17...Adapter, 17A...Flange, 18...Base, 19A...Gap, 19B...Gap, 20...Positioning bush, 21...Slider, 22...Movement plate, 23...Second electric motor, 24...Ball screw, 25...Pusher, 2 6...Rotor, 27...First pulley, 28...Second pulley, 29...Power transmission belt, 30...Reinforcement frame, 31...Sensor, 32...Load cell, 33...Slide mechanism, 33A...Stopper, 33B...Shaft, 33C...Slider, 34...Fixing plate, 35...Stopper, 40...Input device, 41...Storage device, 42...Display, 43...Calculation unit, 44...Machining condition setting unit, 45...Rotation / feed rate control unit, 46...Thrust resistance recording / output unit, 47...Anomaly detection unit, 48...Timer, 49...Machining condition database, AX...Tool axis, J...Drilling jig, J1...Positioning hole, J2...Drilling plate, J3...Positioning pin, J4...Set screw, T...Tool, W...Workpiece.

Claims

1. A tool drive device for hole drilling that is carried by the user by hand and set on the workpiece for use, A spindle with a holder at its tip for holding a tool for drilling holes, An electric motor for rotating the spindle, A guide equipped with a positioning member for positioning the tool drive device on the workpiece, An electric actuator that moves the spindle forward and backward in the direction of the rotation axis of the spindle relative to the guide, A sensor for measuring the cutting resistance transmitted from the tool to the spindle, A controller that controls the electric motor and the electric actuator based on the cutting resistance so that the rotational speed and feed rate of the spindle correspond to the rotational speed and feed rate of the cutting resistance measured by the sensor, Equipped with, A tool drive device comprising a load cell connected to the rear end of the spindle as a sensor for measuring the cutting resistance transmitted from the spindle in the rotation axis direction of the spindle.

2. The electric actuator has a pusher that moves forward and backward in the direction of the rotation axis of the spindle, A slide mechanism is inserted between the pusher and the load cell to change the distance between them in the direction of the spindle's rotation axis, thereby connecting the pusher to the load cell and the spindle. The tool drive device according to claim 1, wherein the pusher moves forward from its retracted position and contacts the load cell, and while a force is acting from the pusher on the load cell and the spindle in the direction of the spindle's forward movement, the load cell detects a load, while when the pusher retracts, the pusher moves away from the load cell and the load cell and spindle retract, so that the load cell does not detect a load.

3. The tool drive device according to claim 2, wherein a stopper is provided on the guide to prevent the load cell from retracting so that it does not come into contact with the pusher after the pusher has retracted and stopped in the retracted position.

4. A method for manufacturing a perforated product, comprising machining a hole in a workpiece using a tool drive device according to any one of claims 1 to 3.

Images