JP7790715B2 - Spindle unit and processing device equipped with same - Google Patents

Description

The present invention relates to a spindle unit and a processing device equipped with the same.

Conventionally, when machining with a rotary tool such as a small-diameter drill, machining equipment equipped with a spindle unit is known that detects the cutting load applied to the rotary tool during machining and controls the machining operation to prevent excessive load from being applied, in order to prevent damage to the rotary tool (see Patent Documents 1-3 below).

In these machining devices, 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.

Japanese Patent Application Laid-Open No. 2001-341014 Japanese Patent Application Laid-Open No. 2007-229826 JP 2008-126395 A

However, with the above-mentioned conventional machining devices, if an excessive torque load is applied during machining, even if the rotary tool itself does not break, excessive torsional deformation occurs in the rotary deformation portion, causing plastic deformation beyond the elastic limit and other factors, resulting in a decrease in detection sensitivity and hindering subsequent torque load measurement. In particular, if the rotary deformation portion of the above-mentioned machining device is designed to accommodate a small-diameter rotary tool, and the rotary tool is then replaced with a larger-diameter rotary tool for machining, greater deformation will occur in the rotary deformation portion. Damage to the rotary deformation portion not only reduces detection sensitivity, but can also impair or even eliminate the detection function itself.

On the other hand, if the rigidity is set high to prevent excessive deformation in the rotational deformation section, it will be possible to accommodate large-diameter rotary tools, but the amount of elastic deformation will decrease, which will reduce the sensitivity to detect torque loads and make it difficult to control the machining to prevent damage to small-diameter rotary tools.

The present invention solves the above problems by providing a spindle unit and a processing machine equipped with the same that can improve detection sensitivity in high load ranges while preventing wear and loss of the detection function in a torque load detection means based on the elastic deformation of the rotational deformation portion.

To solve the above problem, the spindle unit of the present invention comprises 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 workpiece is attached, and a torque load detection means having a rotation deformation portion that connects the base-end rotating portion and the tip-end rotating portion and is configured to be elastically deformable in the rotational direction of the spindle, and that detects the torque load applied to the tool in accordance with the amount of elastic deformation of the rotation deformation portion in the rotational direction. In this spindle unit, the torque load detection means comprises 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, and the second rotation deformation portion is configured to begin elastic deformation when the torque load exceeds a predetermined value within the range of elastic deformation of the first rotation deformation portion. This causes the second rotational deformation portion to begin elastic deformation when the torque load exceeds a predetermined value. This reduces the elastic modulus of the entire rotational deformation portion due to the elastic deformation of the second rotational deformation portion, regardless of the elastic modulus of the first rotational deformation portion. This improves detection sensitivity in areas where the torque load exceeds the predetermined value. Furthermore, improving detection sensitivity in areas where the torque load is equal to or greater than the predetermined value makes it easier to suppress the amount of elastic deformation of the first rotational deformation portion, thereby preventing wear and tear on or loss of the detection function of the torque load detection means due to excessive deformation of the first rotational deformation portion.

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. This allows the deformation rate of the second rotational deformation portion to be greater than the deformation rate of the first rotational deformation portion in regions where the torque load exceeds a predetermined value. Therefore, while the first rotational deformation portion is configured to be able to detect torque loads over a wide range, the large deformation rate (small elastic modulus) of the second rotational deformation portion enables more sensitive detection of torque loads in regions where the torque load is equal to or greater than the predetermined value. 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 avoiding wear and tear on or loss of the detection function of the torque detection means.

In the present invention, the second rotational deformation section preferably includes a base-end attachment section connected to a base-end portion of the main shaft, a tip-end attachment section connected to a tip-end portion of the main shaft, 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, thereby maintaining the relative positions of the base-end attachment section and the tip-end attachment section in the rotational direction, and the initial value of the elastic force corresponds to the predetermined value. This makes it possible to easily configure the second rotational deformation section using a simple mechanism.

In this case, it is desirable 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 even more desirable to provide a detector that outputs a signal to notify when the opposing portions of the base end mounting portion and the tip end mounting portion come into contact with each other, when the opposing portions of the base end mounting portion and the tip end mounting portion begin to approach each other, or when they have approached each other to a predetermined distance. In this way, 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, when they have begun to approach each other, or when they have approached each other to a predetermined distance. By changing or stopping the rotational operation or machining operation of the spindle in response to this 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.

It is also desirable that the base-end mounting portion and the tip-end mounting portion are axially supported so that they can rotate relative to each other around the axis of the main shaft. This allows the base-end mounting portion and the tip-end mounting portion to rotate smoothly in the second rotational deformation portion, thereby enabling efficient detection of torque loads. Furthermore, the elastic force of the elastic body can be reliably applied to both mounting portions, allowing their elastic deformation to be achieved with high precision and good reproducibility.

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

Next, the processing device according to the present invention comprises the spindle unit, a rotational drive means connected to the base-end rotating portion, a feed mechanism that enables the spindle unit to perform a feed operation, a rotary tool or workpiece attached to the tip-end rotating portion, and an installation unit configured to allow the rotary tool or workpiece to be installed. In this case, it is preferable that the processing device further comprises a control unit that controls the rotational drive means and the feed mechanism based on a torque load detection value obtained by a torque load detection means of the spindle unit. It is further preferable that the spindle unit has the thrust load detection means, and that the control unit controls the rotational drive means and the feed mechanism based on the thrust load detection value obtained by the thrust load detection means.

This invention provides a spindle unit and a machining device equipped with the same that can simultaneously improve detection sensitivity in high load ranges and prevent wear and loss of the detection function in a torque load detection means based on the elastic deformation of the rotational deformation portion.

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. FIG. 2 is a schematic perspective view showing the embodiment as viewed obliquely from the base end side. FIG. 2 is a partially enlarged perspective view showing an enlarged portion of a portion around a first rotational deformation portion of the embodiment; FIG. 2 is a partially enlarged perspective view showing an enlarged view of a portion around a second rotational deformation portion of the embodiment. 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. 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. 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. 10A and 10B are explanatory diagrams for explaining in detail the significance of a rotational deformation portion in the embodiment. 5A, 5B, and 5C are explanatory diagrams 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;

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 Figures 1 to 5.

As shown in FIGS. 1 and 2, the spindle unit 10 of this embodiment has a support body 11 that is U-shaped in side view. The support body 11 includes a base body 11a extending along the axial direction of the 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 that constitutes part of the spindle (tip-side rotating portion) is rotatably supported by this radial support portion 12R. The tip of the tip-side rotating shaft 13 is provided with a chuck portion 13a that grips a rotary tool 2 (e.g., a drill, see FIG. 7(a)). The chuck portion 13a may grip a workpiece or other workpiece instead of a tool.

A fixed thrust support portion 12S1 is fixed to the tip 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 light shielding plate 14 attached to the tip rotation shaft 13, and by holding the tip light shielding plate 14 from both axial sides, forms a hydrostatic thrust bearing for the tip rotation shaft 13. The outer periphery of the tip light shielding plate 14 is equipped with numerous tooth-shaped detectable portions 14T, and the rotational phase (angle) of the tip light shielding plate 14 can be detected by the output of photosensors 14S that indicate whether light is transmitted by these detectable portions 14T.

The movable thrust support portion 12S2 is fixed to the inner peripheral portion 15A of the rectangular thrust load detection frame 15. The outer peripheral portion 15B of the thrust load detection frame 15 is fixed to the support body 11 on both the top and bottom 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 the 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 rotating shaft 13, and outputs a detection signal (thrust load detection value) corresponding to the distortion.

One end of the first rotational deformation portion 16A, which is composed of a connecting plate made of an elastic material such as a strip-shaped metal piece, is connected and fixed to the base end of the tip-side rotational 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. Here, 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, 15a. The base end of the torque detection shaft 17 is connected to the second rotational deformation portion 16B.

Furthermore, the torque detection shaft 17 passes through the second rotational deformation portion 16B and is connected to the base-end light shielding plate 19 so that it can rotate about its axis. This base-end light shielding plate 19 is connected and fixed to the output shaft 20a of the motor unit 20. Similar to the tip-end light shielding plate 14 described above, the base-end light shielding plate 19 has a detection target 19T that includes multiple tooth-like structures on its outer periphery, and is configured so that the rotation phase (angle) is detected based on the output of a photosensor 19S that indicates whether light passes through these detection target portions 19T.

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

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 drive direction K. Therefore, when the spindle is rotated, 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 rotation shaft 20a.

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 of 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-side light-shielding plate 19. In the illustrated example, the tip-side mounting portion 161 is configured to be rotatable within a range of 20-70 degrees, more preferably 30-60 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, causing the tip-side mounting portion 161 to rotate, together with the torque detection shaft 17, relative to the base-side light-shielding plate 19 within the above-mentioned angle range in a direction J opposite to the driving direction K of the rotational direction of the main shaft, as shown in Figure 5(d).

As the torque load increases, the angular position of the tip-side mounting portion 161 relative to the base-end 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 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 light-shielding plate 19, and therefore, no further rotational deformation due to the increased torque load occurs in this second rotational deformation portion 16B.

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 the user that the rotation amount limit (R1) has been reached, when the torque load exceeds a predetermined value (T1) and the second rotationally deformed portion 16B has begun 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 (R1) of the rotational deformation of the second rotationally deformed portion 16B or when the limit (R1) is approached, the control unit 150 of the processing device 1, described below, preferably stops processing or changes the processing conditions. Additionally, when the second rotational deformation portion 16B begins to deform, the elastic modulus decreases, so the calculation formula used to derive the torque load detection value T from the overall elastic deformation amount of the rotational deformation portion may be changed accordingly.

Next, we will explain the relationship between the torque load and the amount of elastic deformation of the rotational deformation portion 16 (16A, 16B) in this embodiment. In this embodiment, the first rotational deformation portion 16A (connecting plate) generates torsional deformation D between the tip-end rotating shaft 13 and the torque detection shaft 17 due to the torque load T received by the tip-end rotating shaft 13. The relationship between the torque load T and torsional deformation D at this time is shown by the graph in Figure 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, and the elastic modulus E1 would be constant within the elastic range.

Meanwhile, 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, the positional relationship of the tip-side mounting portion 161 with respect to the base-end light-shielding plate 19 is assumed to be in the state shown in FIG. 5(c) when the torque load T is T1, and the rotation amount R of the tip-side mounting portion 161 with respect to the base-end light-shielding plate 19 is assumed to be 0. At this time, the initial value of the elastic force of the elastic spring 162 corresponds to the torque load T1. Thereafter, as 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 tip-side mounting portion 161 with respect to the base-end light-shielding plate 19) also increases, as shown in the graph in FIG. 6(b). As mentioned above, if the range of rotation angle of the tip-side mounting portion 161 is limited, the amount of rotation R will also be limited, and therefore in the graph of Figure 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 shown by a linear graph, as shown in Figure 6(b), and the elastic modulus E2 is constant within the elastic range.

In this embodiment, the first rotational deformation portion 16A and the second rotational deformation portion 16B are connected in series between the distal rotational shaft 13 and the proximal rotational shaft 20a of the main shaft. Therefore, torque load T is applied equally to both rotational deformation portions. In this state, if the torsional deformation amount D when the first rotational deformation portion 16A is subjected to torque load T1 is D1, the second rotational deformation portion 16B does not undergo elastic deformation in the region where torque load T is less than T1, and therefore its elastic modulus is E1. However, when torque load T exceeds T1, both the first rotational deformation portion 16A and the second rotational deformation portion 16B undergo elastic deformation. As a result, the overall elastic modulus E3 of the rotational deformation portion 16 is expressed as shown in Figure 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 deformation amount R) of the rotational deformation portion 16 has an 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 as the torque load T increases increases.

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, increasing the torque load detection sensitivity. This makes it possible to perform precise detection in areas of high torque load, 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 T1 and above 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-mentioned effects.

Finally, with reference to FIG. 7, an example configuration of the machining device 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 rotary shaft 13, a motor unit 20 that rotates the main shaft of the spindle unit 10, a workpiece holding unit (work spindle unit) 30 that holds a workpiece 3 to be machined by the rotary tool 2, 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 includes an operation setting unit 51, which is an input means for performing various operations and settings, and a machining display unit 52 that displays the machining state of the workpiece 3 by the rotary tool 2. It is also possible to attach a workpiece to the chuck portion 13a of the tip-end rotary shaft 13 of the spindle unit, and then attach a tool to the unit 30 facing it to perform machining.

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, if elastic deformation occurs in the rotationally deformed portion, a phase difference Δt = t ₁ - _{t 0} occurs between the detection signals on the tip and base ends, and the amount of deformation in the rotationally deformed portion in the rotational direction can be detected from this phase difference Δt. Therefore, the torque load can be detected according to this amount of deformation by using the relationship in the graph shown in FIG. 6(c).

In contrast, 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, thrust load detection frame 15, and sensor 15a. Therefore, the machining device 1 monitors the torque load detection value T and 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 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 ensure the machining quality of the workpiece 3.

In the above-described embodiment of the spindle unit 10 and machining apparatus 1 according to the present invention, the spindle unit 10 comprises a spindle including a base-end rotating shaft 20a connected to a motor unit 20, which serves as a rotation drive means, and a tip-end rotating shaft 13 provided with a chuck portion 13a for mounting a rotary tool 2; and a torque load detection means having a rotational deformation portion 16 that connects the base-end rotating shaft 20a and the tip-end rotating shaft 13 and is configured to be elastically deformable in the rotational direction of the spindle, and detecting the torque load applied to the rotary tool 2 in accordance with the amount of elastic deformation of the rotational deformation portion 16 in the rotational direction. In this spindle unit 10, the torque load detection means comprises 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 begin elastic deformation when the torque load exceeds a predetermined value T1 within the range of elastic deformation of the first rotational deformation portion 16A. This allows the second rotationally deformed portion 16B to begin elastic deformation when the torque load exceeds a predetermined value T1. This reduces the elastic modulus of the entire rotationally deformed portion due to the elastic deformation of the second rotationally deformed portion 16B, 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 a critical 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 critical region. Furthermore, increased detection sensitivity in the critical high-load region facilitates precise and accurate processing control, preventing the torque load from exceeding the elastic limit of the first rotationally deformed portion 16A and allowing the first rotationally deformed portion 16A itself to be configured with a certain degree of rigidity. This prevents wear and tear on the detection function of the first rotationally deformed portion 16A.

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 the region where the elastic force of the second rotational deformation portion 16B exceeds its initial value, the rate of increase/decrease of the rotation amount R of the second rotational deformation portion 16B is greater than the rate of increase/decrease of 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 the 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 more sensitive detection of the torque load T.

Furthermore, the second rotational deformation section 16B preferably has a base-end attachment section 19 connected to a portion of the base end of the spindle, a tip-end attachment section 161 connected to a portion of the tip end of the spindle, and an elastic body 162 configured to apply an elastic force in the rotational direction between the base-end attachment section 19 and the tip-end attachment section 161 to maintain the relative rotational positions of the base-end attachment section 19 and the tip-end attachment section 161, with the initial value of the elastic force corresponding to the predetermined value T1. This makes it possible to easily configure the second rotational deformation section 16B using a simple mechanism.

Here, it is desirable that the base-end mounting portion 19 and the tip-end mounting portion 161 are supported so that they can rotate relative to each other around 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 enabling efficient detection of torque loads. Furthermore, the elastic force of the elastic body 162 can be reliably applied to both mounting portions 19, 161, allowing their elastic deformation to be achieved with high precision and good reproducibility.

In this case, it is desirable that the base end attachment portion 19 and the tip end attachment portion 161 each have opposing portions 19P, 161P that are configured to be able to move toward and away from each other in the rotational direction, and that the opposing portions 19P, 161P of the base end attachment portion 19 and the tip end attachment portion 161 move toward each other in the rotational direction when the torque load exceeds the initial value. In this case, it is even more desirable to have 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 come into contact, or when the opposing portions 19P, 161P of the base end attachment portion 19 and the tip end attachment portion 161 begin to move toward each other, or when they have moved toward each other to a predetermined distance. This 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, begin to approach each other, or approach a predetermined distance. By changing or stopping the spindle's rotational drive operation or machining operation in response to this signal, it is possible to know in advance whether the torque load has reached a value corresponding to the limit rotation amount R1, exceeded T1, or is approaching a value corresponding to the limit rotation amount R1. This makes it possible to grasp the state of the second rotational deformation portion and avoid wear or loss of function of the first rotational deformation portion 16A or a decrease in detection sensitivity.

Furthermore, the system preferably further includes a thrust load detection means for detecting the axial thrust load of the main shaft. This thrust load detection means preferably includes a thrust support portion 12S2 that supports the main shaft and is configured to be movable axially together with the main shaft, a fixed portion 12S1 fixed in the axial direction, a detection frame 15 having a first location 15A attached to the thrust support portion, a second location 15B attached to the fixed portion, and a connection portion 15C connecting the first location 15A and the second location 15B, and a strain sensor 15a installed at the connection portion 15C of the detection frame 15. In this way, when the thrust support portion moves axially together with the main shaft relative to the fixed portion, the connection portion of the detection frame deforms, making it possible to detect the thrust load based on the output of the strain sensor 15a.

Next, the machining device 1 of this embodiment comprises a spindle unit 10, a rotational drive means 20 connected to the base end rotating portion 13, a feed mechanism 40 that enables the feed operation of the spindle unit 10, a rotary tool 2 attached to the chuck portion 13a provided on the tip end rotating portion 13, and a workpiece mounting portion 30 configured to enable the mounting of a workpiece 3 so that it can be machined by the rotary tool 2. Furthermore, by further comprising a control portion 50 that controls the rotational drive means 20 and the feed mechanism 40 based on the torque load detection value T from the torque load detection means 16 of the spindle unit 10 and the thrust load detection value S from 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.

Next, we will explain in detail 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. Figure 8 is a graph showing the overall elastic deformation characteristics of the rotationally deformed portion 16 due to torque load T. For ease of explanation, the relationship between the vertical and horizontal axes is reversed compared to Figure 6(c). Here, the torsion angle θ is proportional to the sum of the aforementioned rotational direction torsion deformation amount D and 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, from a safety perspective, 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, with conventional configurations, as shown by the dotted line in the graph, the rate of change of the torsion angle θ in response to changes in the torque load T is small, and the sensitivity of torque load detection based on the torsion angle θ near the maximum safe torque T2 is low. This means that machining control based on the detected torque load value cannot be performed precisely and accurately, and as a result, the torque load may exceed the maximum safe torque T2. Therefore, in practice, it was necessary to perform machining by setting a torque value significantly lower than the maximum safe torque T2.

In contrast, according to this embodiment, by configuring the second rotationally deformed portion 16B to operate at or above a predetermined torque load value T1, which is set lower than the maximum safe torque T2, the elastic modulus E3 of the entire rotationally deformed portion 16 is lowered. Therefore, the range of values 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 the conventional [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 value. 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 enables more stable machining in regions with low cutting resistance 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 rotationally deformed portion 16A is high, it is unlikely to result in a decrease in detection sensitivity in high load areas, and it is also possible to increase the rigidity of the first rotationally deformed portion 16A itself, thereby improving the stability of the processed state and improving resistance to wear and loss of the detection function of the torque load detection means.

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 using equation (7).

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.

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 (the angle when not subjected to external force) between both ends of the spring is θo, the central diameter of the coil portion is D, and the arm lengths from the fixed point to the load point at both ends of the spring are a1 and a2. FIG. 9( b) also schematically shows the elastic spring 162 in its attached state when installed on the second rotational deformation portion 16B. Here, in the attached state, the initial angle between both 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 . Furthermore, FIG. 9( c) 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 is also slightly reduced in diameter, and 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.

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 rotation angle θ per unit torque, then θ = kθ·T, and kθ = 1/kt. Summarizing the above results, for the example of the first rotational deformation portion 16A shown in the calculation of the torsion of a rectangular cross-section beam in Table 1, kθ = 10.34 [deg/Nmm]. For the example of the second rotational deformation portion 16B shown in the calculation of the coil spring in Table 2, 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, the small elastic modulus of the second rotational deformation portion 16B can further enhance the effect of improving detection sensitivity in the high torque load range shown in Figure 8.

The method and apparatus of the present invention are not limited to the illustrated example described above, and various modifications may be made 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 either side 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 (in the illustrated example, the torsional deformation amount D and the rotation amount R) 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.

1...machining device, 2...rotary tool (drill), 3...workpiece, 10...spindle unit, 20...motor unit, 20a...base end rotating shaft (base end rotating part, output shaft) 30...work holding unit, 40...feed mechanism, 50...control part, 51...operation setting part, 52...machining display part, 11...support body, 11a...base body, 11b...tip end supporting part, 11c...base end supporting part, 12R...radial shaft support part, 12S1...fixed thrust shaft support part, 12S2...movable thrust shaft support part, 13...tip end rotating shaft (tip end rotating part), 13a...chuck 14...tip-side light shielding plate, 14T...detection target portion, 14S...photosensor, 15...thrust load detection frame, 15a...sensor, 16A...first rotational deformation portion, 17...torque detection shaft, 18...radial support portion, 19...base-end light shielding plate, 19T...detection target portion, 19S...photosensor, 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 torque load value, D1...corresponding value of torsional deformation amount, R1...limit value of rotation amount

Claims (8)

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. 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 . 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 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. 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 . 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. 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. 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: 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.