Spindle unit and processing device equipped with same

Abstract

To provide means for detecting a torque load based on elastic deformation of a rotary deforming part, which can make both improvement in detection sensitivity in a high-load area and prevention of damage and loss of a detection function compatible.SOLUTION: A spindle unit according to the present invention is equipped with: a spindle which is provided with a base end-side rotary part that is connected to rotary driving means and a tip-side rotary part mounted with a tool or a workpiece; and torque load detecting means that has a rotary deforming part configured to be elastically deformable in a rotating direction of the spindle while connecting the base end-side rotary part to the tip-side rotary part, and which detects a torque load applied to the tool in accordance with an elastic deformation amount in the rotating direction of the rotary deforming part. The torque load detecting means comprises a first front rotary deforming part and a second rotary deforming part which are connected in series to a space between the base end-side rotary part and the tip-side rotary part, where the second rotary deforming part is configured to start to elastically deform when the torque load exceeds a predetermined value of the torque load in a range in which the first rotary deforming part elastically deforms.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a spindle unit and a processing device equipped with the same. [Background technology]

[0002] Conventionally, when machining using a rotary tool such as a small diameter drill, in order to prevent damage to the rotary tool, machining devices equipped with a spindle unit that detects the cutting load applied to the rotary tool during machining and controls the machining operation so that excessive load is not applied have been known (see Patent Documents 1-3 below).

[0003] In these machining devices, in order to detect the torque load applied to the rotary tool, a band-shaped connecting plate (rotational force transmission rod, rotational force transmission member) is installed as a rotational deformation part made of an elastic body that can elastically deform in the rotational direction, and the amount of torsional deformation of this rotational deformation part is detected using a non-contact photosensor, capacitance sensor, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-341014 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-229826 [Patent Document 3] Japanese Patent Application Laid-Open No. 2008-126395 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the conventional machining device, when an excessive torque load is applied during machining, even if the rotary tool itself does not break, excessive torsional deformation occurs in the rotationally deformed portion, causing plastic deformation beyond the elastic limit, etc., which reduces detection sensitivity and interferes with subsequent torque load measurements. In particular, in the above-mentioned machining device, when the rotationally deformed portion corresponding to a small-diameter rotary tool is used, if the rotary tool is replaced with a rotary tool with a larger diameter and machining is performed, greater deformation occurs in the rotationally deformed portion, and damage to the rotationally deformed portion not only reduces detection sensitivity but may also impair or lose the detection function itself.

[0006] On the other hand, if the rigidity is set high so as to prevent excessive deformation of the rotational deformation portion, it will be possible to accommodate large-diameter rotary tools, but there is a problem in that the amount of elastic deformation will decrease, which will reduce the sensitivity to detect torque loads and make it difficult to control the processing to prevent damage to small-diameter rotary tools.

[0007] Therefore, the present invention solves the above problem, and its object is to provide a spindle unit and a processing device equipped with the same that can achieve both improved detection sensitivity in high load areas and prevention of wear and loss of the detection function in a torque load detection means based on the elastic deformation of the rotational deformation part. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a spindle unit including: a spindle having a base-end rotating portion connected to a rotation drive means and a tip-end rotating portion to which a tool or a workpiece is attached; and a torque load detection means having a rotation deformation portion connecting the base-end rotating portion and the tip-end rotating portion and configured to be elastically deformable in a rotational direction of the spindle, the torque load detection means including a first rotation deformation portion and a second rotation deformation portion connected in series between the base-end rotating portion and the tip-end rotating portion, the second rotation deformation portion configured to start elastic deformation when the torque load exceeds a predetermined value within a range in which the first rotation deformation portion elastically deforms. According to this, when the torque load exceeds a predetermined value, the second rotational deformation portion begins to elastically deform, and regardless of the elastic modulus of the first rotational deformation portion, the elastic deformation of the second rotational deformation portion reduces the elastic modulus of the entire rotational deformation portion, thereby improving detection sensitivity in the region where the torque load exceeds the predetermined value.In addition, because detection sensitivity is improved in the region where the torque load is equal to or greater than the predetermined value, it is easier to suppress the amount of elastic deformation of the first rotational deformation portion, and it is possible to prevent wear and loss of the detection function of the torque load detection means due to excessive deformation of the first rotational deformation portion.

[0009] In the present invention, the elastic modulus of the second rotational deformation portion in the rotational direction is preferably smaller than the elastic modulus of the first rotational deformation portion in the rotational direction. Accordingly, in a region where the torque load exceeds a predetermined value, the deformation rate of the second rotational deformation portion is greater than that of the first rotational deformation portion. Therefore, while the first rotational deformation portion is configured to be able to detect torque loads over a wide range, in a region where the torque load is equal to or greater than the predetermined value, the large deformation rate (small elastic modulus) of the second rotational deformation portion enables more sensitive detection of torque loads. Therefore, the improved detection sensitivity in high-load regions provided by the second rotational deformation portion facilitates precise and accurate processing control, thereby preventing excessive torsional deformation in the first rotational deformation portion and increasing the rigidity of the first rotational deformation portion itself, thereby preventing wear and tear on the detection function of the torque detection means.

[0010] In the present invention, it is preferable that the second rotational deformation section has a base-end attachment section connected to a base-end portion of the spindle, a tip-end attachment section connected to a tip-end portion of the spindle, and an elastic body configured to apply an elastic force in the rotational direction between the base-end attachment section and the tip-end attachment section to maintain the relative positions of the base-end attachment section and the tip-end attachment section in the rotational direction, and an initial value of the elastic force corresponds to the predetermined value. This makes it possible to easily configure the second rotational deformation section with a simple mechanism.

[0011] In this case, it is preferable that the base end mounting portion and the tip end mounting portion each include opposing portions configured to move toward and away from each other in the rotational direction, and that the opposing portions of the base end mounting portion and the tip end mounting portion move toward each other in the rotational direction when the torque load exceeds the predetermined value. In this case, it is further preferable to include a detector that outputs a signal notifying the occurrence of contact between the opposing portions of the base end mounting portion and the tip end mounting portion, when the opposing portions of the base end mounting portion and the tip end mounting portion start to approach each other, or when they approach each other to a predetermined distance. In this case, the signal is output when the opposing portions of the base end mounting portion and the tip end mounting portion come into contact with each other in the rotational direction, start to approach each other, or approach each other to a predetermined distance. By changing or stopping the rotational operation or machining operation of the spindle in response to the signal, it is possible to grasp the state of the second rotational deformation portion and avoid damage to the first rotational deformation portion and a decrease in detection sensitivity.

[0012] Furthermore, it is desirable that the base-end mounting portion and the tip-end mounting portion be supported so as to be rotatable relative to each other about the axis of the main shaft. This allows the base-end mounting portion and the tip-end mounting portion to be smoothly rotated in the second rotational deformation portion, thereby enabling efficient detection of torque load. Furthermore, the elastic force of the elastic body can be reliably applied to both mounting portions, allowing their elastic deformation to be realized with high precision and good reproducibility.

[0013] The present invention preferably further includes a thrust load detection means for detecting a thrust load in the axial direction of the spindle. This allows detection of both the torque load and the thrust load, thereby enabling more accurate and reliable understanding of cutting resistance based on both loads and enabling precise machining control. The thrust load detection means preferably includes a movable thrust support member that supports the spindle and is configured to be movable in the axial direction together with the spindle, a fixed thrust support member that is fixed in the axial direction, a detection frame having a first location attached to the movable thrust support member, a second location attached to the fixed thrust support member, and a connecting location connecting the first location and the second location, and a strain sensor installed at the connecting location of the detection frame. When the movable thrust support member moves axially together with the spindle relative to the fixed thrust support member, the connecting location of the detection frame deforms, making it possible to detect the thrust load based on the output of the strain sensor.

[0014] Next, a machining apparatus according to the present invention includes the spindle unit, a rotation drive means connected to the base-end rotating portion, a feed mechanism that enables the spindle unit to feed, a rotary tool or a workpiece attached to the tip-end rotating portion, and a mounting portion configured to mount the rotary tool or the workpiece. In this case, it is preferable that the machining apparatus further includes a control unit that controls the rotation drive means and the feed mechanism based on a torque load detected by a torque load detecting means of the spindle unit. It is further preferable that the spindle unit has the thrust load detecting means, and that the control unit controls the rotation drive means and the feed mechanism based on the thrust load detected by the thrust load detecting means. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a spindle unit and a processing device equipped with the same that can achieve both improved detection sensitivity in high load areas and prevention of wear and loss of the detection function in a torque load detection means based on elastic deformation of a rotational deformation portion. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic perspective view showing an embodiment of a spindle unit and a processing device according to the present invention, viewed obliquely from the tip end side. [Figure 2] FIG. 2 is a schematic perspective view showing the embodiment as viewed obliquely from the base end side. [Figure 3] FIG. 2 is a partially enlarged perspective view showing an enlarged portion of the first rotational deformation portion of the embodiment. [Figure 4] FIG. 4 is a partially enlarged perspective view showing an enlarged portion of the second rotational deformation portion of the embodiment. [Figure 5] 1A is a schematic partial plan view perspective view and FIG. 1B is a schematic partial side view perspective view showing the parts constituting the torque load detection means of the embodiment, and FIG. 1C is an explanatory diagram showing the state of the second rotational deformation part when it is not in operation, and FIG. 1D is an explanatory diagram showing the state of the second rotational deformation part when it is in operation. [Figure 6] Graph (a) shows the relationship between torque load and amount of torsional deformation in the first rotational deformation section, graph (b) shows the relationship between torque load and amount of rotation in the second rotational deformation section, and graph (c) shows the relationship between torque load and the overall amount of rotational deformation of the first rotational deformation section and the second rotational deformation section. [Figure 7] FIG. 1A is a schematic diagram showing the overall configuration of a processing device equipped with a spindle unit; FIG. 1B is an explanatory diagram showing the sensor output of a torque load detection means; and FIG. 1C is a graph showing the relationship between the detected torque load and thrust load values ​​and the control operation of the processing device. [Figure 8] 10A and 10B are explanatory diagrams for explaining in detail the significance of a rotational deformation portion in the embodiment. [Figure 9] 5A, 5B, and 5C are explanatory views each schematically showing a natural state, an attached state, and an actuated state of an elastic spring used in a second rotational deformation portion in the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Next, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. First, the overall configuration of an embodiment of a spindle unit according to the present invention will be described with reference to Figs.

[0018] As shown in FIGS. 1 and 2, the spindle unit 10 of this embodiment includes a support body 11 having a U-shape in side view. The support body 11 includes a base body 11a extending along the axial direction of a spindle (described later), a tip-side support portion 11b extending from the tip of the base body 11a in a direction perpendicular to the axis, and a base-side support portion 11c extending from the base of the base body 11a in a direction perpendicular to the axis. A radial support portion 12R is fixed to the tip-side support portion 11b of the support body 11, and a tip-side rotating shaft (tool holder shaft) 13 constituting a part of the spindle (tip-side rotating portion) is rotatably supported by the radial support portion 12R. A chuck portion 13a is provided at the tip of the tip-side rotating shaft 13 for gripping a rotary tool 2 (e.g., a drill, see FIG. 7(a)). The chuck portion 13a may grip a workpiece, such as a workpiece, instead of a tool.

[0019] A fixed thrust support portion 12S1 is fixed to the tip side support portion 11b of the support body 11 together with the radial support portion 12R. The fixed thrust support portion 12S1 faces the movable thrust support portion 12S2 across the tip side light shielding plate 14 attached to the tip side rotating shaft 13, and holds the tip side light shielding plate 14 from both sides in the axial direction, thereby forming a hydrostatic thrust bearing for the tip side rotating shaft 13. The outer periphery of the tip side light shielding plate 14 is provided with a number of tooth-shaped detectable portions 14T, and the rotation phase (angle) of the tip side light shielding plate 14 can be detected by the output of photosensors 14S that indicate whether or not light is transmitted by these detectable portions 14T.

[0020] The movable thrust support portion 12S2 is fixed to an inner peripheral portion 15A of a thrust load detection frame 15 configured in a rectangular frame shape. An outer peripheral portion 15B of the thrust load detection frame 15 is fixed to the support body 11 on both the upper and lower sides of the inner peripheral portion 15A, thereby holding the movable thrust support portion 12S2 in the axial direction. A sensor 15a such as a strain gauge is attached to a connecting portion 15C between the inner peripheral portion 15A and the outer peripheral portion 15B of the thrust load detection frame 15. The sensor 15a detects distortion of the connecting portion 15C between the inner peripheral portion 15A and the outer peripheral portion 15B of the thrust load detection frame 15, which occurs via the movable thrust support portion 12S2 due to minute axial movement of the tip-end side rotating shaft 13, and outputs a detection signal (thrust load detection value) corresponding to the distortion.

[0021] One end of a first rotational deformation portion 16A, which is a connecting plate made of an elastic material such as a strip of metal, is connected and fixed to the base end of the tip-side rotating shaft 13. The other end of this first rotational deformation portion 16A is connected and fixed to the tip end 17a of the torque detection shaft 17. The torque detection shaft 17 is rotatably supported by a radial support portion 18 attached to the base-end support portion 11c of the support body 11. The radial support portion 18 supports the torque detection shaft 17 without restraining it within at least a partial range in the axial direction. This reduces torsional deformation of the first rotational deformation portion 16A and undesirable effects on the thrust load detection value by the thrust load detection means 12S2, 15, and 15a. The base end of the torque detection shaft 17 is connected to the second rotational deformation portion 16B.

[0022] Furthermore, the torque detection shaft 17 passes through the second rotational deformation portion 16B and is connected to the base-end side light shielding plate 19 so as to be rotatable about its axis. This base-end side light shielding plate 19 is connected and fixed to the output shaft 20a of the motor unit 20. The base-end side light shielding plate 19 has detection target portions 19T including a number of tooth-like structures on its outer periphery, similar to the aforementioned tip-end side light shielding plate 14, and is configured so that the rotation phase (angle) is detected based on the output of a photosensor 19S that indicates whether or not light passes through these detection target portions 19T.

[0023] The second rotational deformation section 16B has a tip-side mounting section 161 connected and fixed to the torque detection shaft 17, a base-end light-shielding plate 19 which is a base-end mounting section connected and fixed to the base-end rotation shaft (base-end rotation section, in the illustrated example, the output shaft of the motor unit 20) 20a, and an elastic spring 162 interposed between the tip-side mounting section 161 and the base-end light-shielding plate 19. In the illustrated example, the elastic spring 162 is a torsion spring, and as shown in FIG. 5(c), when the torque detection shaft 17 is inserted through the coil section, both ends of the elastic spring 162 engage with engagement sections (heads of mounting screws) 19e, 161e of the tip-side mounting section 161 and the base-end light-shielding plate 19, respectively.

[0024] The elastic spring 162 presses the tip-side mounting portion 161 against the base-side mounting portion, the base-side light shielding plate 19, in the rotational driving direction K. Therefore, when the spindle is driven to rotate, if the torque load (for example, the resistance in the rotational direction generated when the rotary tool 2 processes the workpiece 3) is below a predetermined value, the elastic force (initial value) of the elastic spring 162 maintains the positional relationship around the axis of the tip-side mounting portion 161 and the base-side light shielding plate 19, and the torque detection shaft 17 rotates in synchronization with the base-side rotating shaft 20a.

[0025] On the other hand, the tip-side mounting portion 161 is configured to be rotatable within a predetermined angle range in a direction J opposite to the driving direction K, which is the rotational direction around the axis of the main shaft (torque detection shaft 17), by applying an external force against the elastic force of the elastic spring 162 to the base-end light-shielding plate 19. In the illustrated example, the tip-side mounting portion 161 is configured to be rotatable within a range of 20 to 70 degrees, more preferably 30 to 60 degrees, around the axis. Therefore, when the torque load exceeds a predetermined value corresponding to the initial value of the elastic force of the elastic spring 162, the elastic spring 162 elastically deforms, and as a result, the tip-side mounting portion 161, together with the torque detection shaft 17, rotates within the above-mentioned angle range in the direction J opposite to the driving direction K, which is the rotational direction of the main shaft, relative to the base-end light-shielding plate 19, as shown in FIG. 5(d).

[0026] As the torque load increases, the angular position of the tip side mounting portion 161 relative to the base end side light shielding plate 19 further rotates in the reverse direction J, and eventually the opposing surface 161P of the tip side mounting portion 161 comes into contact with the opposing surface 19P of the base end side light shielding plate 19. When the opposing surfaces 161P and 19P come into contact, the tip side mounting portion 161 can no longer rotate further in the reverse direction J relative to the base end side light shielding plate 19, and therefore, in this second rotational deformation portion 16B, further deformation in the rotational direction due to the increase in the torque load does not occur.

[0027] Here, a detector 16S, which is a rotation amount detection means (e.g., a proximity sensor) for the second rotationally deformed portion 16B, may be provided to detect when the opposing surfaces 161P and 19P come into contact with each other, when the opposing surfaces 161P and 19P begin to approach each other, or when the opposing surfaces 161P and 19P have approached each other to a predetermined distance. In this case, the detector 16S notifies when the rotation amount reaches a limit value (R1), when the torque load exceeds a predetermined value (T1) and the second rotationally deformed portion 16B begins to rotate, or when the opposing surfaces 161P and 19P have approached each other to a predetermined distance. When the rotation amount detection means detects the limit value (R1) of the rotational deformation of the second rotationally deformed portion 16B or when the limit value (R1) is approached, it is preferable that the control unit 150 of the processing device 1, which will be described later, stops processing or changes the processing conditions. In addition, when the second rotational deformation portion 16B begins to deform, the elastic modulus decreases, so the calculation formula for deriving the torque load detection value T from the total elastic deformation amount of the rotational deformation portion may be changed accordingly.

[0028] Next, the relationship between the torque load and the elastic deformation of the rotational deformation portion 16 (16A, 16B) in this embodiment will be described. In this embodiment, the first rotational deformation portion 16A (connecting plate) generates a torsional deformation D between the distal end rotating shaft 13 and the torque detection shaft 17 due to the torque load T received by the distal end rotating shaft 13. The relationship between the torque load T and the torsional deformation D at this time is shown by the graph in FIG. 6(a). If the first rotational deformation portion 16A were an ideal elastic body, this relationship would be shown by a linear graph as shown in the figure, and the elastic modulus E1 would be constant within the elastic region.

[0029] On the other hand, in the second rotational deformation portion 16B, the initial value of the elastic force of the elastic spring 162 is set according to the elastic deformation amount of the elastic spring 162 in the initial state shown in FIG. 5(c). At this time, it is assumed that the positional relationship of the distal end side mounting portion 161 with respect to the proximal end side light shielding plate 19 is in the state shown in FIG. 5(c) when the torque load T is T1, and the rotation amount R of the distal end side mounting portion 161 with respect to the proximal end side light shielding plate 19 is 0. At this time, the initial value of the elastic force of the elastic spring 162 corresponds to the torque load T1. Thereafter, when the torque load T increases beyond T1, the elastic spring 162 elastically deforms, and the rotation amount R of the second rotational deformation portion 16B (the rotation angle of the distal end side mounting portion 161 with respect to the proximal end side light shielding plate 19) also increases, as shown in the graph in FIG. 6(b). As described above, when the range of the rotation angle of the tip-side attachment portion 161 is limited, the amount of rotation R is also limited, and therefore, in the graph of Fig. 6(b), the limit value (maximum value) of the amount of rotation R of the second rotational deformation portion 16B is indicated by R1. Even in this case, the relationship between the torque load T and the amount of rotation R is indicated by a linear graph as shown in Fig. 6(b), and the elastic modulus E2 is constant within the elastic region.

[0030] In this embodiment, the first rotational deformation portion 16A and the second rotational deformation portion 16B are connected in series between the distal rotation shaft 13 and the proximal rotation shaft 20a of the spindle. Therefore, the torque load T is applied equally to both rotational deformation portions. In this state, if the amount of torsional deformation D when the first rotational deformation portion 16A receives a torque load T1 is D1, the second rotational deformation portion 16B does not elastically deform in the region where the torque load T is less than T1, and therefore its elastic modulus is E1. However, when the torque load T becomes T1 or greater, both the first rotational deformation portion 16A and the second rotational deformation portion 16B elastically deform. Therefore, the overall elastic modulus E3 of the rotational deformation portion 16A is expressed by the formula shown in FIG. 6(c) and is smaller than the individual elastic moduli E1 and E2. That is, when the torque load T is equal to or greater than T1 and the torsional deformation amount D is equal to or greater than D1, the overall elastic deformation amount (torsional deformation amount D + rotational amount R) of the rotational deformation portion 16 becomes equal to the elastic modulus E3 as shown in FIG. 6(c), and the rate of increase in the overall elastic deformation amount D+R of the rotational deformation portion 16 increases as the torque load T increases.

[0031] In this embodiment, as described above, the elastic modulus of the entire rotationally deformed portion changes significantly at torque load T1, at which the second rotationally deformed portion 16B begins to deform. In particular, the elastic modulus substantially decreases, thereby increasing the torque load detection sensitivity. This allows for accurate detection in the high torque load range, facilitating machining control to avoid damage to the rotary tool 2 due to increased torque load. In particular, in this embodiment, the elastic modulus E3 at torque loads equal to or greater than T1 is smaller than both elastic moduli E1 and E2, resulting in a significant increase in detection sensitivity and therefore a greater degree of the above-described effects.

[0032] Finally, with reference to FIG. 7, a configuration example of the machining apparatus 1 of this embodiment will be described. As shown in FIG. 7(a), this example includes a spindle unit 10 configured to allow a rotary tool 2 to be attached to the chuck portion 13a of the tip-end rotating shaft 13, a motor unit 20 that rotates the main shaft of the spindle unit 10, a workpiece holding unit (work spindle unit) 30 to which a workpiece 3 to be machined by the rotary tool 2 is attached, a feed mechanism 40 that allows the spindle unit 10 to move in the axial direction, and a control unit 50 that controls each unit. The control unit 50 also includes an operation setting unit 51 that is an input means for performing various operations and settings, and a machining display unit 52 that displays the state of machining of the workpiece 3 by the rotary tool 2. Note that it is also possible to attach a workpiece to the chuck portion 13a of the tip-end rotating shaft 13 of the spindle unit, and then attach a tool to the unit 30 facing it to perform machining.

[0033] As described above, in the spindle unit 10, the detection signals of the detection target portions 14T and 19T are output by the photosensors 14S (photosensor 1) and 19S (photosensor 2) in the tip-side light shielding plate 14 and the base-side light shielding plate 19, respectively, as shown in FIG. 7(b). At this time, when elastic deformation occurs in the rotationally deformed portion, a phase difference Δt = t1 - t0 occurs between the detection signals on the tip side and base side, and the amount of deformation in the rotationally deformed portion in the rotational direction can be detected based on this phase difference Δt. Therefore, the torque load can be detected according to the amount of deformation using the relationship shown in the graph in FIG. 6(c).

[0034] On the other hand, in this embodiment, the thrust load applied when the rotary tool 2 is machining the workpiece 3 can be detected by the aforementioned thrust load detection means, namely the movable thrust support 12S2, the thrust load detection frame 15, and the sensor 15a. For this reason, the machining device 1 monitors the torque load detection value T and the thrust load detection value S detected in the spindle unit 10, and when a threshold value TS as shown in Fig. 7(c) is exceeded, the control unit 50 reduces the feed rate of the rotary tool 2 or the workpiece 3, stops the feed operation, temporarily suspends machining, starts a return operation, or changes the rotation speed, in order to prevent damage to the rotary tool 2 or to ensure the machining quality of the workpiece 3.

[0035] In the above-described embodiment of the spindle unit 10 and machining apparatus 1 according to the present invention, the spindle unit 10 includes a spindle including a base-end rotating shaft 20a connected to a motor unit 20 as a rotation drive means, and a tip-end rotating shaft 13 provided with a chuck 13a for mounting a rotary tool 2, and a torque load detection means having a rotational deformation portion 16 connecting the base-end rotating shaft 20a and the tip-end rotating shaft 13 and configured to be elastically deformable in the rotational direction of the spindle, and detecting a torque load applied to the rotary tool 2 in accordance with the amount of elastic deformation in the rotational direction of the rotational deformation portion 16. In the spindle unit 10, the torque load detection means includes a first rotational deformation portion 16A and a second rotational deformation portion 16B connected in series between the base-end rotating shaft 20a and the tip-end rotating shaft 13, and the second rotational deformation portion 16B is configured to start elastic deformation when the torque load exceeds a predetermined value T1 within a range in which the first rotational deformation portion 16A elastically deforms. According to this configuration, when the torque load exceeds a predetermined value T1, the second rotationally deformed portion 16B begins to elastically deform. This reduces the elastic modulus of the entire rotationally deformed portion 16A, regardless of the elastic modulus E1 of the first rotationally deformed portion 16A. This improves the detection sensitivity of the region where the torque load exceeds the predetermined value T1. Therefore, by designating the region of the second rotationally deformed portion 16B exceeding the predetermined value T1 as an important region within the detection range based on the elastic deformation of the first rotationally deformed portion 16A, the detection sensitivity of the torque load detection means can be improved in this important region. Furthermore, since the detection sensitivity can be increased in the important high-load region, precise and accurate processing control is facilitated. This prevents the torque load from exceeding the elastic limit of the first rotationally deformed portion 16A, and allows the rigidity of the first rotationally deformed portion 16A itself to be set to a certain degree. This prevents wear and loss of the detection function of the first rotationally deformed portion 16A.

[0036] Furthermore, because the elastic modulus E2 in the rotational direction of the second rotational deformation portion 16B is smaller than the elastic modulus E1 in the rotational direction of the first rotational deformation portion 16A, in a region where the elastic force of the second rotational deformation portion 16B exceeds the initial value, the rate of increase / decrease in the rotation amount R of the second rotational deformation portion 16B is greater than the rate of increase / decrease in the torsional deformation amount D of the first rotational deformation portion 16A. Therefore, while the first rotational deformation portion 16A is configured to be able to detect the torque load T over a wide range, in a region where the torque load is equal to or greater than the predetermined value T1, the elastic modulus E2 is smaller than the elastic modulus E1 of the second rotational deformation portion 16B, or the elastic modulus E3 of the entire rotational deformation portion is further reduced, enabling detection of the torque load T with better sensitivity.

[0037] Furthermore, it is preferable that second rotational deformation section 16B has a base-end attachment section 19 connected to a portion of the base-end side of the spindle, a tip-end attachment section 161 connected to a portion of the tip-end side of the spindle, and an elastic body 162 configured to apply an elastic force in the rotational direction between base-end attachment section 19 and tip-end attachment section 161 to relatively maintain the rotational positions of base-end attachment section 19 and tip-end attachment section 161, and the initial value of the elastic force corresponds to the predetermined value T1. This makes it possible to easily configure second rotational deformation section 16B with a simple mechanism.

[0038] Here, it is desirable that the base-end mounting portion 19 and the tip-end mounting portion 161 are supported so as to be rotatable relative to each other about the axis of the main shaft. This allows the base-end mounting portion 19 and the tip-end mounting portion 161 to rotate smoothly in the second rotational deformation portion 16B, thereby making it possible to efficiently detect torque loads. Furthermore, the elastic force of the elastic body 162 can be reliably applied to both mounting portions 19, 161, making it possible to realize their elastic deformation modes with high precision and good reproducibility.

[0039] In this case, it is desirable that the base end attachment portion 19 and the tip end attachment portion 161 have opposing portions 19P, 161P that are configured to be able to approach or move away from each other in the rotational direction, and that when the torque load exceeds the initial value, the opposing portions 19P, 161P of the base end attachment portion 19 and the tip end attachment portion 161 approach each other in the rotational direction. In this case, it is further desirable to provide a detector 16S that outputs a signal to notify when the opposing portions of the base end attachment portion 19 and the tip end attachment portion 161 abut on each other, or when the opposing portions 19P, 161P of the base end attachment portion 19 and the tip end attachment portion 161 start to approach each other, or when they have approached each other to a predetermined distance. Since the signal is output when the opposing portions 19P, 161P of the base-end mounting portion 19 and the tip-end mounting portion 161 come into contact in the rotational direction or start approaching each other, or approach each other to a predetermined distance, the signal can be used to change or stop the rotational drive operation or machining operation of the spindle, thereby making it possible to know in advance that the torque load has reached a value corresponding to the limit rotation amount R1, or that the torque load has exceeded T1, or that the torque load is approaching a value corresponding to the limit rotation amount R1. Therefore, it is possible to grasp the state of the second rotational deformation portion, and to avoid wear or loss of function of the first rotational deformation portion 16A, or a decrease in detection sensitivity.

[0040] Furthermore, it is preferable that the device further includes thrust load detection means for detecting a thrust load in the axial direction of the main shaft, and that this thrust load detection means includes a thrust support portion 12S2 that supports the main shaft and is configured to be movable in the axial direction together with the main shaft, a fixed portion 12S1 fixed in the axial direction, a detection frame 15 having a first point 15A attached to the thrust support portion, a second point 15B attached to the fixed portion, and a connecting portion 15C connecting first point 15A and second point 15B, and a strain sensor 15a installed at connecting portion 15C of detection frame 15. In this way, when the thrust support portion moves axially together with the main shaft relative to the fixed portion, the connecting portion of the detection frame deforms, and it becomes possible to detect the thrust load from the output of strain sensor 15a.

[0041] Next, the machining apparatus 1 of this embodiment includes a spindle unit 10, a rotation drive means 20 connected to the base end rotating part 13, a feed mechanism 40 that enables the feed operation of the spindle unit 10, a rotary tool 2 attached to a chuck 13a provided on the tip end rotating part 13, and a workpiece setting part 30 configured to be able to set a workpiece 3 so that it can be machined by the rotary tool 2. In this case, by further including a control part 50 that controls the rotation drive means 20 and the feed mechanism 40 based on the torque load detection value T by the torque load detection means 16 of the spindle unit 10 and the thrust load detection value S by the thrust load detection means 15, it is possible to prevent damage to the rotary tool 2 and improve the machining quality of the workpiece 3.

[0042] Next, the effects of the embodiment based on the elastic deformation characteristics of the first rotationally deformed portion 16A and the second rotationally deformed portion 16B will be described in detail. Figure 8 is a graph showing the overall elastic deformation characteristics of the rotationally deformed portion 16 due to the torque load T. For ease of explanation, the relationship between the vertical and horizontal axes is reversed compared to Figure 6(c). Here, the torsional angle θ is proportional to the sum of the aforementioned torsional deformation amount D in the rotational direction and the rotation amount R. In this case, if the torque load T exceeds the dangerous maximum torque TL (torsion angle θL), the first rotationally deformed portion 16A may undergo plastic deformation, potentially causing the torque load detection means to lose its detection function. For this reason, to ensure safety, it is desirable to stop machining at or below the safe maximum torque T2 (torsion angle θ2), which is smaller than the dangerous maximum torque TL. However, in the conventional configuration, as shown by the dotted line in the graph, the rate of change of the torsion angle θ corresponding to the change in the torque load T is small, and therefore the sensitivity of the detection of the torque load based on the torsion angle θ in the vicinity of the safe maximum torque T2 is low, so that the machining control based on the detected value of the torque load cannot be performed precisely and accurately, and as a result, the torque load may exceed the safe maximum torque T2. Therefore, in practice, it was necessary to perform machining by setting a torque value significantly lower than the above-mentioned safe maximum torque T2.

[0043] On the other hand, according to this embodiment, the second rotationally deformed portion 16B is configured to operate above a predetermined torque load value T1, which is set lower than the maximum safe torque T2. This reduces the elastic modulus E3 of the entire rotationally deformed portion 16. Therefore, the range of the torsion angle θ corresponding to the high load region T1-T2 between the predetermined value T1 and the maximum safe torque T2 is significantly expanded from [θ1-θ2] to [θ1-θ2′]. This improves the detection sensitivity of the torque load in the high load region, enabling precise and accurate machining control based on the detected cutting resistance. This ensures that the torque load is kept below the maximum safe torque T2 and more reliably prevents the torque load from exceeding the maximum safe torque TL. Furthermore, because the detection sensitivity in the high load region is improved, the predetermined value T1 does not need to be set so small. This allows for more stable machining in the low cutting resistance region and reduces the impact of elastic deformation of the second rotationally deformed portion 16B on machining quality. Furthermore, in the configuration of this embodiment, even if the elastic modulus E1 of the first rotational deformation portion 16A is high, it is unlikely to result in a decrease in detection sensitivity in the high load region, and it is also possible to increase the rigidity of the first rotational deformation portion 16A itself, thereby improving the stability of the processing state and improving the resistance to wear and loss of the detection function of the torque load detection means.

[0044] Finally, a specific design example of this embodiment will be described. The following equation 1 is equations (1)-(7) for calculating the torsion of a beam with a rectangular cross section. Here, G is the modulus of transverse elasticity, J is the torsional constant (GJ is torsional rigidity), T is the torsional torque, L is the total length of the beam, h is the height of the cross section, b is the width of the cross section, and C is the aspect ratio. The torsion angle θ is obtained from equation (7).

[0045]

number

[0046] Table 1 shows the design values ​​of the first rotational deformation portion 16A and the results calculated using the above formula. The torsional angle θ is approximately 1.32 degrees when the torque load value is 1 [Nmm], and approximately 7.92 degrees when the torque load value is 6 [Nmm]. In this example, T1 can be set to 6 [Nmm]. Note that kθ = L / GJ is a coefficient corresponding to the elastic modulus, which indicates the change in torsional angle θ per unit torque.

[0047] [Table 1]

[0048] FIG. 9 is an explanatory diagram showing the elastic deformation of the elastic spring 162. FIG. 9(a) schematically shows the elastic spring (torsion spring) 162 in its natural state when not subjected to external force. The natural angle between the ends of the spring (the angle when not subjected to external force) θo, the central diameter of the coil portion D, and the arm lengths from the fixed point to the load point at each end of the spring are a1 and a2, respectively. FIG. 9(b) also schematically shows the elastic spring 162 in its attached state when installed on the second rotational deformation unit 16B. In the attached state, the initial angle between the ends of the spring is θ1, and the deflection angle is ψ1. Strictly speaking, the coil portion also undergoes a slight diameter contraction, and this amount is shown as ΔD1. FIG. 9(c) also schematically shows the actuated state in which the elastic spring 162 further elastically deforms from the attached state when the torque load exceeds a predetermined value T1. Here, the angle between both ends of the spring in the actuated state is θ2, and the deflection angle is ψ2. Strictly speaking, the coil portion also shrinks slightly in diameter, so this amount is shown as ΔD2. In this case, the initial value of the elastic force of the elastic spring 162 in FIG. 9(b) corresponds to a predetermined torque load value T1, and the elastic force of the elastic spring 162 in FIG. 9(c) corresponds to a torque load T2 that is greater than the predetermined value T1. Based on the above points, the elastic spring 162 was designed and its elastic deformation was calculated, and the design values ​​and results are shown in Table 2.

[0049] [Table 2]

[0050] Here, kt represents the torque required to twist the elastic spring 162 and rotate the second rotational deformation portion 16B one degree, and kt = 0.119 [Nmm / deg]. The torque load T is expressed as T = kt·θ using the rotation angle θ. For the elastic spring 162, if kθ is a coefficient (corresponding to the elastic modulus) indicating the change in the rotation angle θ per unit torque, then θ = kθ·T, and kθ = 1 / kt. To summarize the above results, in the example of the first rotational deformation portion 16A shown in Table 1, where the torsion of the rectangular cross-section beam is calculated, kθ = 10.34 [deg / Nmm]. In the example of the second rotational deformation portion 16B shown in Table 2, where the torsion of the coil spring is calculated, kθ = 1.32 [deg / Nmm]. Therefore, in these examples, the elastic modulus E1 of the first rotational deformation portion 16A is 7.8 times the elastic modulus E2 of the second rotational deformation portion 16B. In this way, since the elastic modulus of the second rotational deformation portion 16B is small, the effect of improving the detection sensitivity in the high torque load range shown in FIG. 8 can be further enhanced.

[0051] The method and apparatus of the present invention are not limited to the illustrated example and may be modified in various ways without departing from the spirit and scope of the present invention. For example, in the above embodiment, the distal light-shielding plate 14 and the proximal light-shielding plate 19 are disposed on both sides of the first rotational deformation portion 16A and the second rotational deformation portion 16B of the spindle to detect the overall rotational elastic deformation of the rotational deformation portion and control the processing of the processing device 1 accordingly. However, the rotational elastic deformation amounts of the first rotational deformation portion 16A and the second rotational deformation portion 16B (torsional deformation amount D and rotation amount R in the illustrated example) may be detected independently. In this case, the rotational elastic deformation amount of the first rotational deformation portion 16A can be used to detect the entire range of torque loads under uniform conditions, and the rotational elastic deformation amount of the second rotational deformation portion 16B can be used to perform detailed detection of the range above torque load T1. [Explanation of symbols]

[0052] 1... Machining device, 2... Rotary tool (drill), 3... Workpiece, 10... Spindle unit, 20... Motor unit, 20a... Base end side rotating shaft (base end side rotating portion, output shaft) 30... Work holding unit, 40... Feed mechanism, 50... Control unit, 51... Operation setting unit, 52... Machining display unit, 11... Support, 11a... Base body, 11b... Tip end side supporting portion, 11c... Base end side supporting portion, 12R... Radial shaft support portion, 12S1... Fixed thrust shaft support portion, 12S2... Movable thrust shaft support portion, 13... Tip end side rotating shaft (tip end side rotating portion), 13a... Chuck portion, 14...tip-side light shielding plate, 14T...detected portion, 14S...photo sensor, 15...thrust load detection frame, 15a...sensor, 16A...first rotational deformation portion, 17...torque detection shaft, 18...radial shaft support portion, 19...base-end light shielding plate, 19T...detected portion, 19S...photo sensor, 161...tip-side mounting portion, 162...elastic spring, 161P, 19P...opposing surface, 16S...detector, S...thrust load detection value, T...torque load detection value, T1...predetermined value of torque load, D1...corresponding value of torsional deformation amount, R1...limit value of rotation amount

Claims

1. a spindle including a base end rotating portion connected to a rotation drive means and a tip end rotating portion to which a tool or a workpiece is attached; a torque load detection means having a rotational deformation portion that connects the base end side rotating portion and the tip end side rotating portion and is configured to be elastically deformable in the rotational direction of the spindle, and that detects a torque load applied to the tool in accordance with an amount of elastic deformation of the rotational deformation portion in the rotational direction; A spindle unit comprising: the torque load detection means includes a first rotational deformation portion and a second rotational deformation portion connected in series between the base end side rotating portion and the tip end side rotating portion, and the second rotational deformation portion is configured to start elastic deformation when the torque load exceeds a predetermined value within a range in which the first rotational deformation portion elastically deforms; the torque load detection means detects the torque load when the torque load exceeds the predetermined value based on an amount of elastic deformation in the rotation direction caused by the elastic deformation of the second rotational deformation portion that starts when the torque load exceeds the predetermined value, or based on an amount of elastic deformation in the rotation direction caused by the elastic deformation of the first rotational deformation portion and the elastic deformation of the second rotational deformation portion that starts when the torque load exceeds the predetermined value. Spindle unit.

2. a rotational modulus of elasticity of the second rotational deformation portion in the rotational direction is smaller than a rotational modulus of elasticity of the first rotational deformation portion in the rotational direction; The spindle unit according to claim 1 .

3. A spindle having a base end rotating part connected to a rotary drive means and a tip end rotating part to which a tool or a workpiece is attached; a torque load detection means having a rotational deformation portion that connects the base end side rotating portion and the tip end side rotating portion and is configured to be elastically deformable in the rotational direction of the spindle, and that detects a torque load applied to the tool in accordance with an amount of elastic deformation of the rotational deformation portion in the rotational direction; A spindle unit comprising: the torque load detection means includes a first rotational deformation portion and a second rotational deformation portion connected in series between the base end side rotating portion and the tip end side rotating portion, and the second rotational deformation portion is configured to start elastic deformation when the torque load exceeds a predetermined value within a range in which the first rotational deformation portion elastically deforms; the second rotational deformation portion includes a base-end side mounting portion connected to a base-end side portion of the main shaft, a tip-end side mounting portion connected to a tip-end side portion of the main shaft, and an elastic body configured to apply an elastic force in the rotational direction between the base-end side mounting portion and the tip-end side mounting portion to relatively maintain the positions of the base-end side mounting portion and the tip-end side mounting portion in the rotational direction, and an initial value of the elastic force corresponds to the predetermined value, the base end side mounting portion and the tip end side mounting portion are supported so as to be rotatable relative to each other around the axis of the main shaft, Spindle unit.

4. the base-end side mounting portion and the tip-end side mounting portion each include opposing portions configured to be able to move toward and away from each other in the rotational direction, and when the torque load exceeds the predetermined value, the opposing portions of the base-end side mounting portion and the tip-end side mounting portion are configured to move toward each other in the rotational direction. The spindle unit according to claim 3 .

5. a detector that outputs a signal to notify when the opposing portions of the base end side mounting portion and the tip end side mounting portion come into contact with each other, or when the opposing portions of the base end side mounting portion and the tip end side mounting portion start to approach each other, or when they approach each other to a predetermined distance; The spindle unit according to claim 4.

6. further comprising a thrust load detection means for detecting a thrust load in the axial direction of the main shaft; A spindle unit according to any one of claims 1 to 5.

7. The spindle unit according to any one of claims 1 to 6; a rotation drive means connected to the base end side rotation portion; a feed mechanism that enables the spindle unit to perform a feed operation; a rotary tool or a workpiece attached to the tip side rotating portion; a setting unit configured to be able to set the rotary tool or the workpiece; A processing device comprising:

8. a control unit that controls the rotation drive means and the feed mechanism based on a torque load detection value detected by the torque load detection means of the spindle unit. The processing device according to claim 7.

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