Tool drive device and method for manufacturing a workpiece

Abstract

To provide a tool drive device which enables a workpiece to be drilled stably while preventing clogging of chips in a drill and damage of the drill.SOLUTION: A tool drive device according to an embodiment includes: a drill chuck which holds a drill; a motor which rotates the drill chuck; a housing which houses the motor; and a vibration mechanism which causes the drill chuck to reciprocate in a tool axis direction periodically relative to the housing during rotation of the drill chuck and which separates the drill chuck from the housing at a speed lower than a speed at which the drill chuck is moved close to the housing.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a tool drive device and a method for manufacturing a perforated product.

Background Art

[0002] When drilling with a drill, it is important to cut and discharge the chips so that they do not clog the grooves of the drill. Therefore, conventionally, a mechanism has been proposed for cutting the chips by intentionally vibrating the drill in the tool axis direction (see, for example, Patent Document 1, Patent Document 2, and Patent Document 3).

[0003] Specifically, the spindle can be vibrated in the rotational axis direction by moving a plurality of balls held by a retainer into and out of a recess that rotates with the spindle. That is, when each ball enters the recess, the drill moves away from the drilling target (workpiece) together with the spindle, and when each ball exits the recess, the drill moves toward the workpiece together with the spindle. As a result, the spindle and the drill can be periodically reciprocated in the tool axis direction with a constant amplitude.

[0004] As an example of another mechanism for vibrating the drill, a mechanism for vibrating the spindle by fixing and sliding a cam on the spindle and a mechanism for generating vibration with ultrasonic waves have also been proposed (see, for example, Patent Document 4 and Patent Document 5).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

[0006] However, in conventional vibration mechanisms that vibrate a drill by rolling balls, the drill momentarily separates from the workpiece when each ball enters a recess, and then suddenly pushes towards the workpiece when each ball exits the recess. Therefore, when a user is drilling using a handheld tool drive device, if they release the pressure and hold the tool drive device, they will be pushed back by the drilling reaction force. Consequently, it is not possible to quickly resume drilling after each ball has exited the recess.

[0007] Conversely, if the user grips the handheld tool drive device too tightly, the drill will collide with the workpiece as each ball exits its recess. Therefore, if the workpiece has significantly greater strength than the drill, the drill may break. For example, titanium is much stronger than typical drill materials, so using a conventional vibration mechanism when drilling titanium may result in drill breakage.

[0008] Therefore, when drilling difficult-to-machine materials such as titanium, conventional vibration mechanisms cannot be used. As a result, when drilling metals such as aluminum as well as difficult-to-machine materials such as titanium using a tool drive device without a vibration mechanism, the metal chips that are discharged in a continuous stream cannot be broken up, and there is a risk of the chips clogging the drill groove. If the drill groove becomes clogged with chips, problems such as the drill stopping or the workpiece being damaged may occur.

[0009] In particular, when drilling through a composite material consisting of fiber-reinforced plastics (FRP), also known as composite materials such as glass fiber-reinforced plastics (GFRP) or carbon fiber-reinforced plastics (CFRP), and metal, starting from the FRP side, problems can occur such as metal chips clogging the drill and making continuous drilling difficult, or the inner surface of the FRP being scraped away by the metal chip-clogging drill, resulting in an excessively large hole diameter in the FRP.

[0010] On the other hand, if a mechanism is used that vibrates the spindle by sliding a cam with irregularities, the cam wears down significantly, and compared to a mechanism that vibrates the spindle by rolling balls, there are problems such as unstable vibration and increased frequency of parts replacement. For this reason, in order to vibrate the drill stably over a long period of time, it is practical to use a mechanism that vibrates the spindle by rolling a rotating body such as a ball, which has less friction and wear.

[0011] Therefore, the present invention aims to enable stable drilling of a workpiece while preventing chip clogging and damage to the drill. [Means for solving the problem]

[0012] A tool drive device according to an embodiment of the present invention comprises a drill chuck for holding a drill, a motor for rotating the drill chuck, a housing for housing the motor, and a vibration mechanism for periodically reciprocating the drill chuck in the tool axis direction relative to the housing while the drill chuck is rotating, the vibration mechanism for pulling the drill chuck away from the housing at a speed smaller than the speed at which the drill chuck approaches the housing. The vibration mechanism includes an amplitude adjustment mechanism for adjusting the amplitude of the reciprocating movement, a plurality of balls spaced apart and rotatable on the same circle between the drill chuck and the housing, and a sliding surface provided directly or indirectly on one of the drill chuck and the housing, which the plurality of balls contact while rolling during the rotation of the drill chuck, having a plurality of steps spaced at equal intervals so that the plurality of balls fall simultaneously during the forward rotation of the drill chuck, and which smoothly changes from each step toward the adjacent step so that no steps are created for the plurality of balls to climb during the forward rotation of the drill chuck.

[0013] Further, the method for manufacturing a perforated product according to an embodiment of the present invention manufactures a perforated product by holding a drill with the above-described tool driving device and perforating a perforation target with the drill rotated by the tool driving device.

Brief Description of the Drawings

[0014] [Figure 1] Partial cross-sectional view showing the configuration of a tool driving device according to a first embodiment of the present invention. [Figure 2] Enlarged partial longitudinal cross-sectional view of the vibration mechanism shown in FIG. 1. [Figure 3] Left side view in a state where balls are housed in a fixed ring included in the vibration mechanism shown in FIG. 2. [Figure 4] Right side view of a rotating ring included in the vibration mechanism shown in FIG. 2. [Figure 5] View in which a cross-section at position A-A of the rotating ring shown in FIG. 4 is developed on a plane. [Figure 6] View in which unevenness is emphasized by enlarging only the thickness direction of the developed cross-sectional view of the rotating ring shown in FIG. 5. [Figure 7] Right side view showing an example in which the range where the bottom surface of a groove provided in the rotating ring shown in FIG. 2 is inclined is limited to the vicinity of the valley side of each step. [Figure 8] View in which a cross-section at position B-B of the rotating ring shown in FIG. 7 is developed on a plane. [Figure 9] View in which unevenness is emphasized by enlarging only the thickness direction of the developed cross-sectional view of the rotating ring shown in FIG. 8. [Figure 10] Partial cross-sectional view showing the configuration of a tool driving device according to a second embodiment of the present invention. [Figure 11] Enlarged partial longitudinal cross-sectional view of the vibration mechanism shown in FIG. 10. [Figure 12] Left side view in a state where a plurality of balls are held by a ball retainer shown in FIG. 11. [Figure 13] Right side view of the rotating ring shown in FIG. 11. [Figure 14] Longitudinal cross-sectional view showing the configuration of a vibration mechanism provided in a tool driving device according to a third embodiment of the present invention. [Figure 15] Left side view of the fixed ring shown in FIG. 14. [Figure 16] Left side view of the ball retainer shown in FIG. 14 in a state of holding a plurality of balls. [Figure 17] Right side view of the rotating ring shown in FIG. 14. [Figure 18] Fig. showing an example in which a scale representing the amplitude of the vibration of the drill and the drill chuck generated by the vibration mechanism shown in FIG. 14 is shaken. [Figure 19] Vertical cross-sectional view showing the configuration of a first modification of the vibration mechanism provided in the tool driving device according to the third embodiment of the present invention. [[ID=!15]] [[ID=!16]] [Figure 20] Front view showing the configuration of a second modification of the vibration mechanism provided in the tool driving device according to the third embodiment of the present invention.

Mode for Carrying Out the Invention

[0015] The tool driving device and the method for manufacturing a workpiece to be drilled according to the embodiment of the present invention will be described with reference to the accompanying drawings.

[0016] (First Embodiment) (Configuration and Function) FIG. 1 is a partial cross-sectional view showing the configuration of a tool driving device according to the first embodiment of the present invention.

[0017] The tool driving device 1 is a device that holds and rotationally drives a drill T in order to drill a workpiece W to be drilled. Incidentally, the drilling tool held by the tool driving device 1 is sometimes called a drill bit, and the tool driving device 1 itself that rotates the drill bit may also be referred to as a drill.

[0018] The tool driving device 1 may be provided with not only a rotation mechanism for the drill T but also a feed mechanism. That is, the user may push out the tool driving device 1 itself to feed the drill T toward the workpiece W, or the drill T may be fed toward the workpiece W fully automatically or semi-automatically by the tool feed mechanism.

[0019] Note: There seems to be a formatting issue in the original text where lines 15 and 16 have an exclamation mark (!) added in front of the ID in the translation. It's not clear if this is intentional or an error in the original text. If it's an error, the translation should be adjusted accordingly.The tool drive device 1 can consist of a drill chuck 2 for holding the drill T, a motor 3 for rotating the drill chuck 2, and a housing 4 for housing the motor 3. The motor 3 may be electric, hydraulic, pneumatic, or of any other type. The output shaft of the motor 3 can function as a spindle 5 that rotates the drill chuck 2 together with the drill T. In other words, the output shaft of the motor 3 can be integrated with the spindle 5. Of course, the output shaft of the motor 3 and the spindle 5 may be arranged parallel or on the same line, and torque may be transmitted by gears or the like.

[0020] If the tool drive device 1 is handheld, a grip 6 for the user to hold is provided on the housing 4. A switch 7 for operating the motor 3 can be provided on or near the grip 6.

[0021] Furthermore, the tool drive unit 1 is provided with a vibration mechanism 8 that periodically reciprocates the drill T, drill chuck 2, and spindle 5 in the tool axis AX direction relative to the housing 4 while the drill T, drill chuck 2, and spindle 5 are rotating. When the spindle 5 is reciprocated in the tool axis AX direction, if it is a typical motor 3, the motor 3 will also reciprocate in the tool axis AX direction. For this reason, for example, a gap can be provided between the motor 3, which is normally housed without any gaps in the motor case 3A, and the motor case 3A, so that the motor 3 can reciprocate in the tool axis AX direction.

[0022] By using the vibration mechanism 8 to periodically reciprocate the drill T and drill chuck 2 in the tool axis AX direction by a distance of only a small amount compared to the feed rate, specifically a distance of 0.01 mm to 0.15 mm, metal chips that are discharged in a continuous chain can be broken up. In other words, by vibrating the drill T and drill chuck 2 with an amplitude of 0.01 mm to 0.15 mm, the chips can be broken up. As a result, chip clogging of the drill T can be prevented.

[0023] This is because when the drill T and drill chuck 2 move toward the housing 4, the drill T, which is cutting, temporarily separates from the workpiece W, interrupting the drilling process. After that, if feed is applied to the drill T and drill chuck 2, cutting can be resumed. This type of intermittent drilling, which involves alternating between cutting and interruption to discharge chips, is also called peck drilling, peck drilling, or step drilling.

[0024] Furthermore, if the amplitude of the vibration is too small, specifically less than 0.01 mm, the chip-breaking effect will be insufficient, and if the amplitude of the vibration is too large, specifically exceeding 0.15 mm, it will be difficult for the user to hold the tool drive device 1 by hand.

[0025] In particular, the vibration mechanism 8 is configured to pull the drill T and drill chuck 2 away from the housing 4 at a speed lower than the speed at which they approach the housing 4. That is, the drill T vibrates at different speeds during the forward and return journeys. More specifically, the movement of the drill T and drill chuck 2 toward the housing 4 to temporarily pull the drill T away from the workpiece W and interrupt drilling is performed instantaneously, while the movement of the drill T and drill chuck 2 toward the housing 4 to bring the temporarily pulled-away drill T and drill chuck 2 toward the workpiece W again is performed at the slowest possible speed.

[0026] As a result, the drill T is instantly pulled away from the workpiece W, ensuring that the chips are reliably broken by interrupting the drilling process. At the same time, when drilling is resumed, the drill T moves towards the workpiece W at a low speed, preventing the drill T from colliding with the workpiece W and breaking. Furthermore, because the drill T moves towards the workpiece W at a low speed immediately after drilling is resumed, the rate of increase in the drilling reaction force is also reduced, avoiding the inconvenience of the user being pushed back by a sudden increase in the drilling reaction force.

[0027] The vibration mechanism 8 can be composed of a sliding surface 9 having irregularities corresponding to the movement speed of the drill T and the drill chuck 2, and a plurality of balls 10 that roll on the sliding surface 9 while the drill chuck 2 is rotating. The vibration mechanism 8 can also be constructed by using a rotating body such as a roller with a rotating shaft, a disc-shaped member with smooth, lubricated protrusions, etc., which slides on the sliding surface 9 with irregularities instead of the balls 10. However, the following explanation will use the most practical case, using balls 10, as an example.

[0028] Figure 2 is an enlarged longitudinal section view of the vibration mechanism 8 shown in Figure 1, Figure 3 is a left side view of the vibration mechanism 8 shown in Figure 2 with the ball 10 housed in the fixed ring 11, Figure 4 is a right side view of the rotating ring 12 shown in Figure 2, Figure 5 is a planar view of the cross section of the rotating ring 12 at position AA shown in Figure 4, and Figure 6 is a view that emphasizes the unevenness by enlarging the unfolded cross section of the rotating ring 12 shown in Figure 5 only in the thickness direction of the rotating ring 12.

[0029] Multiple balls 10 are arranged at equal intervals and spaced apart so as to be able to roll on the same circle between the drill chuck 2 and the housing 4. The sliding surface 9 on which the multiple balls 10 roll and make contact during the rotation of the drill chuck 2 can be provided directly or indirectly on either the drill chuck 2 or the housing 4.

[0030] To this end, in the illustrated example, a fixed ring 11 with a through hole for the spindle 5 at its center is fixed to the housing 4, and a rotating ring 12 with a through hole for the spindle 5 at its center is fixed to the drill chuck 2, with a gap between them so that they do not come into contact with each other. Alternatively, a female thread may be formed on the inner surface of the through hole in the rotating ring 12, while a male thread may be formed on the surface of the spindle 5, thereby fixing the rotating ring 12 to the spindle 5 as well. Consequently, the fixed ring 11 does not rotate relative to the housing 4, but the rotating ring 12 rotates together with the drill chuck 2 and the spindle 5 relative to the housing 4 and the fixed ring 11.

[0031] Furthermore, a portion of the balls 10 are rotatably housed in multiple spherical recesses, which are arranged at equal intervals on the same circle within the fixing ring 11. As a result, each of the balls 10 rolls in a fixed position relative to the housing 4 to which the fixing ring 11 is fixed. The fixing ring 11 also functions as a ring-shaped ball retainer that holds a portion of the balls 10 in a rotatable manner.

[0032] On the other hand, the rotating ring 12 has a sliding surface 9 with irregularities. The shape of the irregularities on the sliding surface 9 is such that there are multiple steps 9A at equal intervals so that multiple balls 10 fall simultaneously when the drill chuck 2 is rotating in the forward direction, and the shape is such that there are no steps for the multiple balls 10 to climb when the drill chuck 2 is rotating in the forward direction, by smoothly changing from one step 9A to the next. In other words, when the drill T and drill chuck 2 are rotated in the forward direction by the forward rotation of the motor 3, as illustrated in Figures 5 and 6, the shape of the irregularities on the sliding surface 9 is such that multiple balls 10 fall simultaneously from the steps 9A on the sliding surface 9, and there are no steps for them to climb, and they roll up a smooth inclined surface toward the next step 9A.

[0033] As a result, while drilling is being performed by rotating the drill T and drill chuck 2 in the forward direction, the sliding surface 9 of the rotating ring 12 fixed to the drill chuck 2 rotates relative to the multiple balls 10. Due to the drilling reaction force from the workpiece W, the multiple balls 10 simultaneously fall from the step 9A of the sliding surface 9. Consequently, the drill T and drill chuck 2 are momentarily and temporarily pulled away from the workpiece W and move closer to the housing 4. This interrupts the drilling and breaks up the chips.

[0034] Conversely, after multiple balls 10 have fallen from a higher position to a lower position on the step 9A, feed is applied to the drill T and drill chuck 2, generating a drilling reaction force from the workpiece W again. As a result, each ball 10 rolls along the smoothly changing sliding surface 9, making contact with it, and reaches the higher position of the adjacent step 9A. Therefore, the drill T and drill chuck 2 do not collide with the workpiece W at high speed, and the drilling reaction force from the workpiece W does not increase locally. Consequently, the drill T is not damaged, and the user can continue drilling stably without being pushed back by the drilling reaction force from the workpiece W.

[0035] The sliding surface 9 can be formed as the inner surface of a groove 9B whose length is aligned with the rotational direction, including the forward and reverse rotational directions of the drill chuck 2, as shown in the figure. In this case, the groove 9B has a slope, where the depth gradually decreases from each step 9A formed on the inner surface of the groove 9B toward the adjacent step 9A.

[0036] Normally, forward rotation is clockwise, so the groove 9B of the rotating ring 12 rotates clockwise with respect to each ball 10 along with the drill chuck 2. Consequently, each ball 10 rotates counterclockwise relative to the groove 9B of the rotating ring 12. For this reason, as illustrated in Figures 4 to 6, each step 9A is provided in the groove 9B in a direction that causes each ball 10 to fall when it rotates counterclockwise relative to the annular groove 9B. In other words, when each ball 10 rotates counterclockwise relative to the annular groove 9B (in the unfolded diagrams of Figures 5 and 6, when each ball 10 moves to the right relative to the groove 9B), there are steps 9A that cause the ball to fall over the ridge, but there are no steps in the groove 9B that cause the ball to climb over the ridge. Note that when performing special drilling that involves rotating the drill T counterclockwise, the direction of the steps 9A and the slope should be reversed.

[0037] Alternatively, the sliding surface 9 may be formed not as the inner surface of the groove 9B, but as a tapered surface having multiple steps 9A in the same direction as the rotational direction of the drill chuck 2, or as a corrugated surface having multiple steps 9A in the same direction as the rotational direction of the drill chuck 2.

[0038] When forming a groove 9B as the sliding surface 9, a V-groove with a V-shaped cross-section or a groove with a flat bottom surface may be formed. However, as shown in the figure, if at least a part of the cross-section of the groove 9B is made into an arc with the same radius as the radius of the ball 10 so that each ball 10 fits into a part of the bottom surface of the groove 9B, the ball 10 will make line contact with the groove 9B rather than point contact, thus slowing down the wear progression of the ball 10. When the cross-section of the groove 9B is made into an arc, the groove 9B is often formed by groove machining using a ball end mill. For this reason, an R-chamfer may be applied to the valley side of each step 9A.

[0039] Furthermore, in the examples shown in Figures 5 and 6, the bottom surface of the groove 9B is sloped over the entire area between adjacent steps 9A. However, if the edges of the steps that the ball 10 climbs can be eliminated, the area where the bottom surface is sloped can be limited to a portion starting from the valley side of each step 9A, and the remaining portion towards the mountain side of each adjacent step 9A does not need to be sloped.

[0040] Figure 7 is a right side view showing an example in which the range inclined of the bottom surface of the groove 9B provided in the rotating ring 12 shown in Figure 2 is limited to the vicinity of the valley side of each step 9A; Figure 8 is a planar view of the cross section of the rotating ring 12 at position BB shown in Figure 7; and Figure 9 is a view in which the unfolded cross section of the rotating ring 12 shown in Figure 8 is enlarged only in the thickness direction of the rotating ring 12 to emphasize the unevenness.

[0041] As illustrated in Figures 7 to 9, if the edges of the steps that the ball 10 climbs can be removed, the range in which the bottom surface of the groove 9B slopes can be limited to the vicinity of the valley side of each step 9A. In this case, since the bottom surface of the groove 9B does not slope on the mountain side of each step 9A, the shape of the rotating ring 12 can be simplified. For this reason, the manufacturing of the rotating ring 12 can also be simplified. In particular, the smaller the drop of each step 9A, the shorter the range in which the bottom surface of the groove 9B is sloped can be, and the edges of the steps that the ball 10 climbs can be removed to the point where they can be ignored.

[0042] Because the sliding surface 9 formed on the inner surface of such a sloped groove 9B has multiple steps 9A at equal intervals, if the drill T and drill chuck 2 are rotated in the forward direction at a predetermined rotational speed, periodic vibrations occur in the drill T and drill chuck 2 with an amplitude equal to the drop of the steps 9A. In other words, each time one of the balls 10 crosses the edge of a step 9A, the direction of movement of the drill T and drill chuck 2 is reversed, and drilling is interrupted.

[0043] Therefore, the height difference of the step 9A from which the ball 10 falls can be determined to be between 0.01 mm and 0.15 mm, as described above, so that the user can hold the tool drive device 1 by hand and the amplitude of vibration is desirable from the viewpoint of obtaining a chip-breaking effect. Furthermore, the size of the ball 10 is not important; what is important is the amount of movement of the ball 10 in the tool axis AX direction, i.e., the height difference of the step 9A. However, reducing the size of the ball 10 has the advantage of making the vibration mechanism 8 more compact, while conversely, increasing the size of the ball 10 has the advantage of slowing down the progression of ball wear.

[0044] The number of balls 10 should be three or more so that the runout of the drill T and drill chuck 2 does not increase even when a drilling reaction force is applied from the workpiece W. As the number of balls 10 increases, the number of steps 9A increases in proportion to the number of balls 10, so the distance between adjacent steps 9A becomes shorter. Consequently, as the number of balls 10 increases, the vibration frequency of the drill T and drill chuck 2 increases.

[0045] As the vibration frequency of the drill T and drill chuck 2 increases, the frequency of drilling interruptions increases, which has the effect of making the chips finer, but it also shortens the cutting time per unit time. For this reason, it is desirable from the viewpoint of not increasing the cutting time to limit the number of balls 10 to the number necessary to make the chips fine enough to sufficiently avoid chip clogging of the drill T. In the case of drilling typical metal materials such as aluminum under typical drilling conditions such as hole diameter, depth, rotational speed of the drill T, and number of teeth of the drill T, three balls 10 are considered to be sufficient.

[0046] Furthermore, even if the number of steps 9A on the sliding surface 9 is not the same as the number of balls 10, but is a multiple of the number of balls 10, it is still possible to vibrate the drill T and drill chuck 2 at a predetermined frequency. However, increasing the number of steps 9A will shorten the cutting time per unit time, similar to increasing the number of balls 10, so it is appropriate to keep the number of steps 9A to the minimum necessary to obtain the chip-breaking effect.

[0047] The conditions regarding the shape of the balls 10 and the sliding surface 9 are the same even when the sliding surface 9 is formed on a fixed ring 11 fixed to the housing 4, rather than on a rotating ring 12 fixed to the drill chuck 2. When the sliding surface 9 is formed on a fixed ring 11 fixed to the housing 4, a spherical recess can be provided on the rotating ring 12 fixed to the drill chuck 2 to serve as a ball retainer. In that case, multiple balls 10 will roll in a fixed position relative to the drill chuck 2 to which the rotating ring 12 is fixed. Therefore, when the drill T and drill chuck 2 are rotated in the forward direction, multiple balls 10 will also rotate in the forward direction and roll on the sliding surface 9.

[0048] The tool drive device 1 described above generates periodic vibrations that instantly pull the drill T and drill chuck 2 away from the workpiece W while slowly bringing them closer to the workpiece W, using a vibration mechanism 8 composed of multiple balls 10, etc., that roll on a sliding surface 9 having an appropriate uneven shape.

[0049] (effect) With the tool drive device 1, the drill T is intermittently and periodically pulled away from the workpiece W, resulting in finely divided chips that are easier to discharge. This prevents deterioration of hole quality, such as excessive hole diameter in FRP caused by chip clogging in the groove of the drill T. Therefore, by holding the drill T with the tool drive device 1 and drilling the workpiece W with the drill T rotated by the tool drive device 1, it is possible to manufacture a product with a well-quality hole. For example, even when drilling a workpiece W made of FRP such as CFRP and a metal such as aluminum or titanium layered together, as illustrated in Figure 1, the metal chips are divided and do not clog in the groove of the drill T, so a product with a well-quality hole can be manufactured.

[0050] Furthermore, in conventional vibration mechanisms that vibrate the drill by rolling a ball, abrupt changes in the vibration direction occur not only when the ball enters the recess but also when the ball exits the recess. As a result, problems such as the drill colliding with the workpiece or the user being pushed back due to a momentary increase in the drilling reaction force can occur. However, in the case of the vibration mechanism 8 of the tool drive device 1, the speed at which the drill T approaches the workpiece W is small, and the change in drilling reaction force is also small. Therefore, problems such as the drill T colliding with the workpiece W and being damaged, and the inconvenience of being pushed back by the drilling reaction force when the user holds the tool drive device 1 by hand can be avoided.

[0051] In addition, in conventional vibration mechanisms where a ball is moved in and out of a recess, there is a problem in that the ball and the edge of the recess wear down as the ball repeatedly comes into contact with the edge of the recess when it comes out of the recess. However, in the case of the vibration mechanism 8 of the tool drive device 1, there is no step on the sliding surface 9 that the ball 10 climbs up, so wear of the ball 10 caused by repeated collisions with the edge of a step can be avoided.

[0052] (Second embodiment) Figure 10 is a partial cross-sectional view showing the configuration of a tool drive device according to a second embodiment of the present invention.

[0053] In the tool drive device 1A of the second embodiment shown in Figure 10, the configuration differs from the tool drive device 1 of the first embodiment in that the multiple balls 10 constituting the vibration mechanism 8A are rolled while rotating relative to both the drill chuck 2 and the housing 4. Since the other configurations and operations of the tool drive device 1A of the second embodiment are substantially the same as those of the tool drive device 1 of the first embodiment, the same or corresponding components are denoted by the same reference numerals and their descriptions are omitted.

[0054] When the positions of multiple balls 10 are to be rotated without being fixed to both the drill chuck 2 and the housing 4, a ring-shaped ball retainer 20 that holds some of the multiple balls 10 in a rotatable manner can be provided without being fixed to either the drill chuck 2 or the housing 4, so as to be rotatable in the rotational direction including the forward and reverse rotational directions of the drill chuck 2, that is, around the tool axis AX. The ball retainer 20 can be rotatably positioned in the space formed between a fixed ring 11 fixed to the housing 4 and a rotating ring 12 fixed to the drill chuck 2, as illustrated in Figure 10.

[0055] Figure 11 is an enlarged longitudinal section view of the vibration mechanism 8A shown in Figure 10, Figure 12 is a left side view of the ball retainer 20 shown in Figure 11 holding multiple balls 10, and Figure 13 is a right side view of the rotating ring 12 shown in Figure 11.

[0056] As illustrated in Figures 10 and 12, a ball retainer 20, which has through holes formed in a ring-shaped plate material corresponding to the number of balls 10, can hold multiple balls 10 and be placed between the fixed ring 11 and the rotating ring 12. In the example shown in Figures 10 and 12, the fixed ring 11 is provided with a cylindrical edge having an inner diameter larger than the outer diameter of the rotating ring 12, so the ball retainer 20 can be housed between the fixed ring 11 and the rotating ring 12.

[0057] The rotating ring 12 is provided with a sliding surface 9 with a step 9A, which is formed as the inner surface of a sloped groove 9B similar to that of the first embodiment, as illustrated in Figure 13. Of course, when forming a sloped groove 9B in the rotating ring 12, the bottom surface of the groove 9B may be locally or partially inclined, as illustrated in Figures 7 to 8.

[0058] As shown in the figure, when the ball retainer 20 is rotatable relative to both the fixed ring 11 and the rotating ring 12, a drilling reaction force acts both between the ball 10 and the rotating ring 12 and between the ball 10 and the fixed ring 11. As a result, each ball 10 rotates and moves relative to both the fixed ring 11 and the rotating ring 12 due to the frictional forces between the ball 10 and the rotating ring 12 and between the ball 10 and the fixed ring 11. In other words, each ball 10 rolls while rotating relative to the drill chuck 2 and the housing 4.

[0059] Therefore, as illustrated in Figure 10, a groove 11A of a constant depth may be formed in the fixing ring 11 for each ball 10 to roll. If the cross-sectional shape of the groove 11A is an arc so that the inner surface of the groove 11A fits with each ball 10, each ball 10 will roll while making line contact with the inner surface of the groove 11A, thereby slowing down the rate of wear of each ball 10. Of course, a sliding surface 9 with a step 9A, such as the inner surface of a groove 9B with a slope, may also be formed on the fixing ring 11 side.

[0060] According to the second embodiment described above, in addition to the same effects as the first embodiment, the frictional force between each ball 10 and the fixed ring 11 and the rotating ring 12 can be dramatically reduced. That is, when a fixed ring 11 with a spherical recess is used as a ball retainer to hold multiple balls 10, as in the first embodiment, each ball 10 will inevitably roll while sliding against either the fixed ring 11 or the rotating ring 12. For this reason, when the rotational speed of the drill T and drill chuck 2 is high, the frictional force between each ball 10 and the fixed ring 11 and the rotating ring 12 increases, and there is a risk that each ball 10 will wear out in a short time.

[0061] In particular, when drilling with a small-diameter drill T with a tool diameter of about 3 mm to 10 mm, the rotational speed of the drill T is often between 2000 rpm and 6000 rpm. Actual prototype tests conducted under these drilling conditions confirmed that the balls 10 can be heated to over 100°C due to friction and wear down, causing a decrease in the diameter of the balls 10. Therefore, when drilling with a small-diameter drill T, it is preferable from the viewpoint of ensuring tool life to adopt the second embodiment, which can reduce the frictional force between each ball 10 and the fixed ring 11 and rotating ring 12 to a negligible degree.

[0062] (Third embodiment) Figure 14 is a longitudinal cross-sectional view showing the configuration of a vibration mechanism provided in a tool drive device according to a third embodiment of the present invention.

[0063] The tool drive device 1B in the third embodiment shown in Figure 14 differs from the tool drive devices 1 and 1A in the first and second embodiments in that the vibration mechanism 8B is provided with a function to adjust the amplitude of vibration generated in the drill T and drill chuck 2, and a function to switch it off without generating vibration. Since the other configurations and operations of the tool drive device 1B in the third embodiment are substantially the same as those of the tool drive devices 1 and 1A in the first and second embodiments, only the vibration mechanism 8B is shown, and the same or corresponding components are denoted by the same reference numerals and their descriptions are omitted.

[0064] In the third embodiment, the vibration mechanism 8B is configured so that the amplitude of the vibration generated in the tool axis AX direction of the drill T and the drill chuck 2, that is, the amplitude of the reciprocating movement of the drill T and the drill chuck 2 in the tool axis AX direction, can be adjusted by the amplitude adjustment screw 30.

[0065] In this case, by determining the length of the amplitude adjustment screw 30 so that the amplitude of the drill T and drill chuck 2 in the tool axis AX direction can be adjusted to zero, it becomes possible to switch the amplitude of the reciprocating movement of the drill T and drill chuck 2 ON / OFF. In other words, it becomes possible to switch between a vibration mode in which the drill T and drill chuck 2 reciprocate in the tool axis AX direction and a non-vibration mode in which the drill T and drill chuck 2 do not reciprocate in the tool axis AX direction.

[0066] Figure 14 shows an example in which the vibration mechanism 8B is configured by rotatably arranging a ball retainer 20, which holds a plurality of balls 10, between a fixing ring 11 fixed to the housing 4 and a rotating ring 12 fixed to the drill chuck 2, similar to the second embodiment. Therefore, the amplitude of vibration of the drill T and the drill chuck 2 can be adjusted by adjusting the distance between the fixing ring 11 and the rotating ring 12 with the amplitude adjustment screw 30.

[0067] Figure 15 is a left side view of the fixed ring 11 shown in Figure 14, Figure 16 is a left side view of the ball retainer 20 shown in Figure 14 holding multiple balls 10, and Figure 17 is a right side view of the rotating ring 12 shown in Figure 14.

[0068] Similar to the second embodiment, a ball retainer 20 holding a plurality of balls 10, as shown in Figures 14 and 16, can be rotatably positioned between a fixed ring 11 fixed to the housing 4 and a rotating ring 12 fixed to the drill chuck 2. In this case, a groove 11A of constant depth can be formed in the fixed ring 11, as shown in Figures 14 and 15, while a groove 9B with a step 9A of 0.01 mm to 0.15 mm can be formed in the rotating ring 12 as a sliding surface 9, as shown in Figures 14 and 17. Of course, the depth of the groove 9B in the rotating ring 12 may be gradually reduced between the steps 9A, as shown in Figure 13. Also, the groove 11A in the fixed ring 11 may be omitted.

[0069] Furthermore, the groove 11A of the fixed ring 11 and the groove 9B of the rotating ring 12 can serve as a path for each ball 10 to move relative to the fixed ring 11 and the rotating ring 12. In this case, when the rotating ring 12 rotates with the drill chuck 2 and spindle 5 relative to the housing 4 and the fixed ring 11, the balls 10 pass through the step 9A of the rotating ring 12, which receives the drilling reaction force from the workpiece W along with the drill T and the drill chuck 2, thereby generating vibrations in the tool axis direction AX in the drill T and the drill chuck 2.

[0070] However, as the distance between the fixed ring 11 and the rotating ring 12 is increased, the amount of movement of the rotating ring 12 in the tool axis AX direction gradually decreases even when the ball 10 passes over the step 9A of the rotating ring 12. In other words, as the distance between the fixed ring 11 and the rotating ring 12 is increased, the amplitude of vibration of the drill T and the drill chuck 2 decreases, and when the distance between the fixed ring 11 and the rotating ring 12 reaches a certain distance, the amplitude becomes zero and the vibration stops.

[0071] This is because, when a drilling reaction force from the workpiece W is applied to the rotating ring 12 fixed to the drill chuck 2, if there is a gap equivalent to the diameter of the ball 10 between the groove 11A of the fixed ring 11 and the groove 9B of the rotating ring 12, the ball 10 will, in principle, pass through the gap formed between the groove 11A of the fixed ring 11 and the groove 9B of the rotating ring 12 without resisting the drilling reaction force.

[0072] Therefore, as shown in Figures 14 and 15, the fixing ring 11 and the housing 4 can be connected by an amplitude adjustment screw 30, and the fixing ring 11 can be configured to slide relative to the housing 4 in the direction of the tool axis AX. In this case, since the rotating ring 12 is fixed to the drill chuck 2, the distance between the fixing ring 11 and the rotating ring 12 can be finely adjusted by sliding the fixing ring 11 in the direction of the tool axis AX.

[0073] In the example shown in Figure 14, a female thread is formed on the inner surface of the cylindrical portion of the fixing ring 11, and a male thread is formed on the outer surface of the cylindrical portion of the housing 4. However, the male and female threads can be reversed. That is, the fixing ring 11 can be inserted into the housing 4 instead of the front end of the housing 4 being inserted into the inside of the fixing ring 11.

[0074] In order to allow the fixing ring 11 to slide relative to the housing 4 in the tool axis AX direction, it is necessary to leave a gap between the fixing ring 11 and the housing 4 that changes slightly in distance. Therefore, an elastic O-ring 31 made of rubber or the like can be provided between the fixing ring 11 and the housing 4. As a result, even if the fixing ring 11 is moved in the tool axis AX direction by an order of 0.01 mm to 0.1 mm, the O-ring 31 will compress by the amount of movement of the fixing ring 11, so that the fixing ring 11 can be supported in the tool axis AX direction by the O-ring 31.

[0075] On the other hand, as shown in Figures 14 and 15, the fixing ring 11 has an internal thread formed in its radial direction, with the depth direction being the same as the radial direction of the fixing ring 11, allowing the fixing screw 32 to be tightened. This prevents the fixing ring 11 from rotating relative to the housing 4 by tightening the fixing screw 32 and pressing its tip against the housing 4. In other words, the fixing screw 32 can be provided as a stopper to prevent the fixing ring 11 from rotating relative to the housing 4 and from sliding in the direction of the tool axis AX.

[0076] The fixing screw 32 can be a slotted screw tightened with a slotted screwdriver, or a thumb screw such as a wing bolt or knurled screw. Also, since the fixing screw 32 can prevent the fixing ring 11 from sliding in the tool axis AX direction, the O-ring 31 may be omitted. However, supporting the fixing ring 11 with both the O-ring 31, which can support the fixing ring 11 in the tool axis AX direction, and the fixing screw 32, which applies radial pressure to the fixing ring 11, will lead to the stabilization of the fixing ring 11.

[0077] By finely adjusting the position of the fixing ring 11 in the tool axis AX direction as the tightening amount of the amplitude adjustment screw 30, it becomes possible to continuously adjust the amplitude of the reciprocating movement of the drill T and drill chuck 2 in the tool axis AX direction steplessly. Furthermore, by ensuring a sufficient stroke of the amplitude adjustment screw 30, it becomes possible to adjust the amplitude of the reciprocating movement of the drill T and drill chuck 2 in the tool axis AX direction to zero, thereby allowing the drill T and drill chuck 2 to rotate while their reciprocating movement is stopped.

[0078] Therefore, the amplitude of vibration of the drill T and drill chuck 2 can be adjusted so that the chips are divided into appropriate sizes according to the drilling conditions such as the size of the drill T, the material of the workpiece W, and the rotational speed of the drill T. As described above, the amplitude of vibration of the drill T and drill chuck 2 changes according to the amount of slide of the fixing ring 11 in the tool axis AX direction, and the amount of slide of the fixing ring 11 in the tool axis AX direction changes according to the amount of rotation of the fixing ring 11 relative to the housing 4, which corresponds to the tightening amount of the amplitude adjustment screw 30. Therefore, a scale may be displayed to check the amount of rotation of the fixing ring 11 so that the user can easily fine-tune the amplitude of vibration of the drill T and drill chuck 2 manually.

[0079] Figure 18 shows an example of a scale indicating the amplitude of vibrations generated by the vibration mechanism 8B shown in Figure 14 for the drill T and drill chuck 2.

[0080] For example, as shown in Figure 18, the position of the fixing screw 32 can be used as the reference position to mark the housing 4. In the example shown in Figure 18, there are three approximate vibration amplitudes: large, medium, and small, and the alignment position for when vibration is turned OFF and not generated is also displayed.

[0081] Therefore, the user can easily fine-tune the amplitude of the vibration to match the drilling conditions by referring to the scale. In other words, the user can fix the position of the fixing ring 11 in the tool axis direction AX by rotating the fixing ring 11 with the reference of the scale and tightening the fixing screw 32 at the desired rotation position.

[0082] In the third embodiment described above, an amplitude adjustment screw 30 for variably adjusting the amplitude of vibration of the drill T and drill chuck 2 is provided in the vibration mechanism 8B as an amplitude adjustment mechanism, so that the amplitude of vibration of the drill T and drill chuck 2 can be adjusted according to the drilling conditions.

[0083] (effect) Therefore, according to the third embodiment, the amplitude of vibration generated in the drill T and drill chuck 2 can be adjusted so that the size of the chips is appropriate, depending on the drilling conditions such as the tool diameter of the drill T used, the material of the workpiece W, and the rotational speed of the drill T. As a result, drilling quality can be improved by avoiding chip clogging, and drilling can be stabilized.

[0084] As a practical example, when the drill T is small in diameter and rotates at high speed, the amount of material removed is small, so the amplitude can be reduced to reduce cutting interruption time due to vibration. On the other hand, when the drill T is large in diameter and rotates at low speed, the amount of material removed is large, so the amplitude can be increased to ensure that the chips are properly broken up.

[0085] As another example, when drilling a composite material of metal and FRP from the metal side, the problem of excessively large holes in the resin can be prevented by breaking up the metal chips. However, when drilling a workpiece W made of a single material, it may be preferable to avoid generating vibrations from the standpoint of shortening processing time. In other words, if the chips are not discharged in a connected state in the first place, or if the chips not being broken up does not pose a problem in terms of drilling quality, vibrating the drill T and drill chuck 2 will interrupt the process and increase the processing time.

[0086] In such cases, the vibration of drill T and drill chuck 2 can be switched off to avoid an increase in processing time. In other words, not only can the amplitude of the vibration be adjusted, but it can also be switched on and off to achieve an optimal balance between drilling quality and processing time.

[0087] Furthermore, in the first and second embodiments, the amplitude of vibration of the drill T and drill chuck 2 can be changed by replacing the rotating ring 12 with another rotating ring 12 having a different groove depth 9B, or by replacing the fixed ring 11 with another fixed ring 11 having a different groove depth 11A.

[0088] In contrast, in the third embodiment, since it is not necessary to replace the components of the vibration mechanism 8B, not only is the user's working time reduced, but it is also unnecessary to manufacture multiple components. Furthermore, in the third embodiment, since the amplitude of the vibration can be continuously changed, it is not necessary to change the drilling conditions in accordance with the amplitude of the vibration, such as changing the thrust during drilling. In other words, instead of determining the drilling conditions according to the settable amplitude of vibration, the amplitude of the vibration can be adjusted according to the drilling conditions.

[0089] (First modified example of the third embodiment) Figure 19 is a longitudinal cross-sectional view showing the configuration of a first modified example of a vibration mechanism provided in a tool drive device according to a third embodiment of the present invention.

[0090] As described in the first and second embodiments, the groove 9B with a step 9A and slope may be formed on the stationary ring 11 instead of the rotating ring 12, as shown in Figure 19. In that case, if a groove 12A of constant depth is formed on the rotating ring 12, each ball 10 and the rotating ring 12 will be in line contact, thereby slowing down the wear of the balls 10.

[0091] Furthermore, the amplitude adjustment screw 30 may be formed on the fixed ring 11 as shown in Figure 14, or on the rotating ring 12 as shown in Figure 19. In other words, the amplitude adjustment screw 30 can be formed on at least one of the fixed ring 11 and the rotating ring 12.

[0092] In the example shown in Figure 19, a cylindrical portion is formed on the drill chuck 2 side of the rotating ring 12, and a female thread for the amplitude adjustment screw 30 is formed on its inner surface. On the other hand, a male thread for the amplitude adjustment screw 30 is formed on the outer surface of the drill chuck 2. Therefore, by adjusting the tightening amount of the amplitude adjustment screw 30, the rotating ring 12 can be slid relative to the drill chuck 2 in the direction of the tool axis AX. As a result, the distance between the fixed ring 11 and the rotating ring 12 can be changed.

[0093] When moving the rotating ring 12 relative to the drill chuck 2, it is necessary to change the gap between the rotating ring 12 and the drill chuck 2. For this reason, an O-ring 31 can be placed between the rotating ring 12 and the drill chuck 2. In addition, the rotating ring 12 can be fixed to the drill chuck 2 with a fixing screw 32.

[0094] Furthermore, the amplitude adjustment screw 30 may be formed between the spindle 5 and the rotating ring 12. That is, a male screw may be formed on the outer surface of the spindle 5 and a female screw on the inner surface of the rotating ring 12. In this case as well, if a cylindrical portion is formed on the drill chuck 2 side of the rotating ring 12, the rotating ring 12 can be fixed to the drill chuck 2 from the outside with a fixing screw 32.

[0095] (Second modified example of the third embodiment) Figure 20 is a front view showing the configuration of a second modified example of a vibration mechanism provided in a tool drive device according to a third embodiment of the present invention.

[0096] In the example described above, an amplitude adjustment screw 30 is provided in the vibration mechanism 8B as an amplitude adjustment mechanism to adjust the amplitude of vibration of the drill T and drill chuck 2 by changing the distance between the fixed ring 11 and the rotating ring 12. However, an amplitude adjustment mechanism can also be constructed using a key 40 and a keyway 41.

[0097] As a specific example, as shown in Figure 20, a cylindrical key 40 can be made to protrude from the tip of the housing 4, which is inserted into the cylindrical portion of the fixing ring 11, with the radial direction of the fixing ring 11 as its longitudinal direction. On the other hand, a keyway 41 can be formed in the fixing ring 11 that allows the key 40 to slide in the longitudinal direction.

[0098] Then, by rotating the fixing ring 11 relative to the housing 4, the path of the keyway 41 can be determined so that the fixing ring 11 slides in the tool axis AX direction when the key 40 is slid along the keyway 41. In this way, the fixing ring 11 can be slid in the tool axis AX direction relative to the housing 4 according to the amount of rotation of the fixing ring 11.

[0099] In the example shown in Figure 20, a stepped keyway 41 is formed on the fixing ring 11, having a shape in which three parallel keyways 41, whose longitudinal direction is the circumferential direction of the fixing ring 11, are connected at their ends. Therefore, when the fixing ring 11 is rotated, the fixing ring 11 can be slid in steps in the tool axis AX direction by a distance corresponding to the steps in the keyway 41.

[0100] Therefore, by determining the position of the keyway 41 to match the distance between the fixed ring 11 and the rotating ring 12, which is the adjustment target, the distance between the fixed ring 11 and the rotating ring 12 can be set to the target distance. The step in the keyway 41 corresponds to the amount of slide of the fixed ring 11, and is therefore on the order of 0.01 mm to 0.1 mm.

[0101] In the example shown in Figure 20, the fixed ring 11 has keyways 41 formed on it for sliding the fixed ring 11 to a position where the gap between the fixed ring 11 and the rotating ring 12 is sufficiently large to turn off vibration, for sliding the fixed ring 11 to a position where the gap between the fixed ring 11 and the rotating ring 12 is moderate to generate vibrations of small amplitude, and for sliding the fixed ring 11 to a position where the gap between the fixed ring 11 and the rotating ring 12 is minimal to generate vibrations of large amplitude.

[0102] Alternatively, a keyway 41 with a spiral shape in the longitudinal direction may be formed in the fixing ring 11, and the fixing ring 11 may be fixed to the housing 4 with a fixing screw 32. In that case, the fixing ring 11 can be continuously slid in the direction of the tool axis AX.

[0103] Alternatively, the keyway 41 may be a groove with a bottom surface instead of a slit that goes all the way through, or the key 40 may be made to protrude from the inner surface of the fixing ring 11 toward the housing 4, and the keyway 41 may be formed in the housing 4. However, if a keyway 41 that goes all the way through is formed in the fixing ring 11, the position of the key 40 can be confirmed from the outside.

[0104] The amplitude adjustment mechanism, consisting of a key 40 and a keyway 41, can also be provided between the rotating ring 12 and the drill chuck 2. In other words, the amplitude adjustment screw 30 shown in Figure 19 can be replaced with the amplitude adjustment mechanism consisting of a key 40 and a keyway 41.

[0105] (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. [Explanation of symbols]

[0106] 1, 1A, 1B Tool drive unit 2 Drill chucks 3 motors 3A motor case 4 cabinets 5 spindles 6 Grips 7 Switches 8, 8A, 8B vibration mechanism 9. Sliding surface 9A Step 9B Groove 10 balls 11 Retaining ring 11A Groove 12 Rotating Rings 12A groove 20 Ball Retainers 30 Amplitude adjustment screw 31 O-rings 32 Fixing screws 40 keys 41 keyways AX tool axis T-Drill Double job

Claims

1. A drill chuck that holds the drill, A motor for rotating the drill chuck, A housing for the motor, A vibration mechanism that periodically reciprocates the drill chuck in the tool axis direction relative to the housing while the drill chuck is rotating, comprising a vibration mechanism that pulls the drill chuck away from the housing at a speed smaller than the speed at which the drill chuck approaches the housing, It has, The vibration mechanism is An amplitude adjustment mechanism for adjusting the amplitude of the aforementioned reciprocating movement, A plurality of balls are arranged between the drill chuck and the housing, spaced apart and rotatable on the same circle at equal intervals, A sliding surface provided directly or indirectly on one of the drill chuck and the housing, on which the plurality of balls roll and make contact during the rotation of the drill chuck, having a plurality of equally spaced steps so that the plurality of balls fall simultaneously during the forward rotation of the drill chuck, and having a smooth transition from each step toward the adjacent step so that no steps are created on which the plurality of balls climb during the forward rotation of the drill chuck; A tool drive device having the following features.

2. The tool drive device according to claim 1, wherein the amplitude of the reciprocating movement is adjusted to zero by the amplitude adjustment mechanism, thereby enabling the drill chuck to rotate while the reciprocating movement is stopped.

3. The vibration mechanism is A ball retainer that holds the plurality of balls so as to be able to roll, further comprising a ball retainer that is rotatably mounted around the tool shaft, The tool drive device according to claim 1, wherein the plurality of balls are rolled while being rotated relative to the drill chuck and the housing.

4. A method for manufacturing a workpiece, comprising holding a drill with a tool drive device according to any one of claims 1 to 3, and drilling a workpiece to be drilled with the drill rotated by the tool drive device.

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