WO2024154671A1

WO2024154671A1 - Rotating cylinder

Info

Publication number: WO2024154671A1
Application number: PCT/JP2024/000665
Authority: WO
Inventors: 民和西宮
Original assignee: 株式会社北川鉄工所
Priority date: 2023-01-18
Filing date: 2024-01-12
Publication date: 2024-07-25
Also published as: JP7326636B1; JP2024101883A

Abstract

Provided is a rotating cylinder capable of attaining a reduction in energy loss.　This rotating cylinder comprises a base and a rotor configured so as to be rotatable relative to the base, the rotating cylinder being equipped with a state switch part whereby a gap between the base and the rotor in a radial-direction opposed portion, which is a portion where the base faces the rotor in the radial direction, is switched between a first state and a second state, the gap in the second state being larger than that in the first state.

Description

Rotating Cylinder

The present invention relates to a rotating cylinder installed in a machine tool.

Patent Document 1 discloses a technology for cooling the inside of an oil reservoir in a rotating cylinder used in a machine tool by rotating multiple fans that rotate together with the rotor, thereby ventilating outside air into the oil reservoir.

JP 2011-51040 A

The technology in Patent Document 1 efficiently exhausts the generated heat and suppresses the temperature rise of the rotating cylinder, but since the heat generation itself is not suppressed, energy loss occurs due to the heat generation.

The present invention was made in consideration of these circumstances, and provides a rotating cylinder that can reduce energy loss.

According to the present invention, the following inventions are provided.
[1] A rotating cylinder comprising a base and a rotating body configured to be rotatable relative to the base, wherein a state switching unit is provided that can switch a gap between the base and the rotating body at a radially opposing portion where the base and the rotating body radially oppose each other between a first state and a second state, and the second state is a state in which the gap is larger than in the first state.
[2] A rotating cylinder as described in [1], wherein the state switching portion includes a switching piston provided on the base at the radially opposing portion, and the first state and the second state are switched in accordance with the movement of the switching piston in the axial direction of the rotating body.
[3] A rotating cylinder as described in [2], wherein the switching piston is cylindrical, and an inner peripheral surface of the switching piston and an outer peripheral surface of the rotating body are provided with a convex portion and a concave portion, respectively, so that in a first state, the convex portion of the switching piston faces the convex portion of the rotating body, and in a second state, the convex portion of the switching piston faces the concave portion of the rotating body, and the concave portion of the switching piston faces the convex portion of the rotating body.
[4] A rotating cylinder according to any one of [1] to [3], wherein the rotating body comprises a rotating body main body, a main piston, first and second cylinder chambers, and first and second pressure retention valves, the base comprises first and second ports configured to be able to supply and discharge a working fluid, the first and second ports being respectively disposed in the radially opposing portions, the first port and the first cylinder chamber being connected through a first flow path, and the second port and the second cylinder chamber being connected through a second flow path, the main piston being configured to be movable by supplying and discharging the working fluid to the first and second cylinder chambers, and the first and second pressure retention valves being configured to be able to hold the pressure of the working fluid supplied into the first and second cylinder chambers, respectively.

In the rotating cylinder of the present invention, the gap between the base and the rotor can be switched between a first and a second state. Therefore, the gap between the base and the rotor is reduced only when it is necessary to reduce the gap, and in other cases, the gap between the base and the rotor is increased, thereby suppressing heat generation associated with the rotation of the rotor and reducing energy loss.

FIG. 1A is a perspective view of a rotating cylinder 1 according to one embodiment of the present invention, and FIG. 1B is a perspective view of the rotating cylinder 1 as viewed from a different angle. 2 is a cross-sectional view of the rotating cylinder 1 of FIG. 1 , taken along a line parallel to the rotation axis C of the rotor 3 and passing through the rotation axis C and the state switching portion 22. 3 is a view showing the rotary cylinder 1 of FIG. 2 disassembled into a base 2 and a rotary body 3. FIG. 4 is a diagram showing the base 2 in FIG. 3 disassembled into a base body 21 and a state switching portion 22. FIG. 3 is a cross-sectional view of the rotating cylinder 1 of FIG. 2 taken along a plane perpendicular to the axis of rotation C and passing through the first port 2a. FIG. 6A is an enlarged view of area A in FIG. 2, showing gap 1b in a first state, and FIG. 6B shows the state after the switching piston 25 constituting the state switching unit 22 has been moved to change the state of gap 1b from the first state to the second state. FIG. 6B is an exploded view of FIG.

The following describes an embodiment of the present invention. The various features shown in the following embodiment can be combined with each other. Furthermore, each feature can be an invention independently.

1. Configuration of Rotary Cylinder 1 A rotary cylinder 1 according to an embodiment of the present invention will be described with reference to FIGS.

1 and 2, a rotating cylinder 1 according to an embodiment of the present invention includes a base 2 and a rotor 3 configured to be rotatable relative to the base 2. The base 2 is usually connected to a machine tool so as to be in a substantially non-rotating state. The rotor 3 is fixed to the spindle of the machine tool and rotates about a rotation axis C in association with the rotation of the spindle.

As shown in Figures 2 and 3, the rotor 3 incorporates a reciprocating main piston 32. The rotary cylinder 1 is configured to supply a working fluid (e.g., hydraulic oil) for reciprocating the main piston 32 into the rotor 3 through the base 2. As shown in Figure 1, the base 2 is provided with first and second ports 2a, 2b configured to be able to supply and discharge the working fluid. As shown in Figure 2, the ports 2a, 2b are provided in the radially opposing portion 1a where the base 2 and the rotor 3 are radially opposed. In the radially opposing portion 1a, the working fluid is exchanged between the base 2 and the rotor 3. Sealing members (e.g., O-rings) are provided between various members to prevent leakage of the working fluid.

1-2. Rotating body 3
As shown in Fig. 3, the rotor 3 includes a rotor main body 31, a main piston 32, first and second cylinder chambers 33a, 33b, and first and second pressure retention valves 34a, 34b. The rotor main body 31 includes a front body 31a, a rear body 31b, and a rear cap 31c. The rear body 31b is connected to the front body 31a by a bolt 31d (shown in Fig. 1A). The rear cap 31c is connected to the rear body 31b by a bolt 31e. The rotor main body 31 is fixed to the spindle by a bolt 31f that passes through the front body 31a and the rear body 31b.

The main piston 32 is disposed in the accommodation space 31g of the rotor main body 31 and is freely slidable in the direction of the rotation axis. The main piston 32 comprises a cylindrical portion 32a, a flange portion 32b, and a connecting portion 32c. The accommodation space 31g comprises a cylindrical space 31g1 and a flange space 31g2. The cylindrical portion 32a is accommodated in the cylindrical space 31g1, and the flange portion 32b is accommodated in the flange space 31g2. The flange space 31g2 is divided into cylinder chambers 33a, 33b by the flange portion 32b. The main piston 32 is configured to be movable by supplying and discharging working fluid to the first and second cylinder chambers 33a, 33b.

The flange portion 32b is connected to the rotor body 31 by a pin 32d, allowing the main piston 32 to rotate integrally with the rotor body 31. In one example, the connecting portion 32c is a female thread provided on the inner surface of the cylindrical portion 32a, and by fixing one end of a connecting bar to the connecting portion 32c and connecting the other end to a chuck device, the reciprocating motion of the main piston 32 can be transmitted to the chuck device, allowing the chuck to hold and release the workpiece.

The rotor body 31 is provided with a first flow path 31h1 that connects the first port 2a and the first cylinder chamber 33a, and a second flow path 31h2 that connects the second port 2b and the second cylinder chamber 33b, and the working fluid can be supplied to and discharged from the cylinder chambers 33a and 33b through the first and second flow paths 31h1 and 31h2. The pressure retention valves 34a and 34b are disposed in the flow paths 31h1 and 31h2, respectively, and are configured to be able to retain the pressure of the working fluid in the cylinder chambers 33a and 33b. The pressure retention valves 34a and 34b are each configured as pilot-operated check valves, and the passage and blocking of the working fluid can be controlled by the pilot pressure.

1-3. Base 2
1-3-1. Basic configuration of the base 2 As shown in Figs. 3 and 4, the base 2 includes a base body 21, a state switching unit 22, a bearing 23, and an oil reservoir 24. The base body 21 includes a front body 21a and a rear body 21b. The rear body 21b is connected to the front body 21a by a bolt 2c (shown in Fig. 1A). The base body 21 is cylindrical, and the state switching unit 22 and the bearing 23 are provided inside the base body 21. The rotating body 3 is supported by a pair of bearings 23 and can rotate relative to the base 2. The area between the pair of bearings 23 is the radially opposed portion 1a. In the radially opposed portion 1a, the base 2 and the rotating body 3 face each other in a non-contact manner through a minute gap 1b (shown in Fig. 6).

The oil reservoir 24 is connected to the base body 21 by bolts (not shown). The base body 21 is provided with a drain port 21c that communicates with the oil reservoir 24, and a portion of the working fluid supplied through ports 2a and 2b is discharged from the drain port 21c through gap 1b. Therefore, gap 1b is filled with working fluid.

When the rotor 3 rotates, the working fluid in the gap 1b is sheared, generating a resistance torque T due to the viscosity of the working fluid. The load caused by this resistance torque is converted into heat almost 100%. The amount of heat generated per unit time Q is expressed by the following formula, and the amount of heat generated Q is inversely proportional to the shear section radius gap h. Increasing h reduces the amount of heat generated, but increases the amount of working fluid discharged through the drain port 21c (the amount of drainage).
T: Resistance torque ω: Rotational speed τ: Shear stress μ: Viscosity of working fluid h: Radius gap of shear section S: Area of shear section R: Radius of shear section L: Total width of shear section

1-3-2. Configuration of state switching unit 22 The state switching unit 22 is configured to be able to switch the gap 1b between the base 2 and the rotor 3 at the radially opposing portion 1a between a first state shown in Fig. 6A and a second state shown in Fig. 6B. In the second state, the gap 1b is larger than in the first state. The state switching unit 22 is preferably disposed between a pair of bearings 23.

In this embodiment, the state switching unit 22 includes a switching piston 25 provided on the base 2 at the radially opposing portion 1a. The switching piston 25 is a cylindrical member, with the inner surface of the switching piston 25 facing the rotating body 3 and the outer surface of the switching piston 25 facing the base body 21. The first state and the second state are switched with the axial movement of the switching piston 25 (movement in the direction in which the rotation axis C extends; left and right direction in FIG. 2). The drive mechanism for moving the switching piston 25 is not particularly limited, but in this embodiment, the switching piston 25 is biased in one direction by a biasing member 26 such as a spring, and is movable in the other direction (opposite to the one direction) by a working fluid pressure (e.g. hydraulic) mechanism.

The working fluid is supplied and discharged through a state change port 21d provided in the base body 21 so as to change the working fluid pressure applied to the axial end face of the switching piston 25. In this embodiment, when no working fluid is supplied to the state change port 21d, the switching piston 25 is pushed by the biasing member 26, causing the gap 1b to be in the second state, and when the switching piston 25 is moved against the biasing force of the biasing member 26 by supplying working fluid to the state change port 21d, the gap 1b is in the first state. The switching piston 25 is connected to the base body 21 by the biasing member 26 and cannot rotate relative to the base body 21.

As shown in Figures 4 and 5, ports 2a and 2b are composed of through holes 2a1 and 2b1 provided in base body 21 and through holes 2a2 and 2b2 provided in switching piston 25. In the first state, through holes 2a1 and 2a2 communicate with each other to form port 2a, and through holes 2b1 and 2b2 communicate with each other to form port 2b. This makes it possible to supply and discharge the working fluid to and from the inner surface of switching piston 25. On the other hand, in the second state, the positions of through holes 2a1 and 2a2 are shifted from each other, and the positions of through holes 2b1 and 2b2 are shifted from each other. Therefore, in the second state, working fluid cannot be flowed in or discharged through ports 2a and 2b. In this way, switching piston 25 also functions as a switching valve that controls the opening and closing of ports 2a and 2b. Even in the second state, the working fluid flows through the small gap between the base body 21 and the switching piston 25, so it is possible to oil the bearing 23 and expel the working fluid remaining in the gap 1b to promote cooling.

As shown in FIG. 7, the inner peripheral surface of the switching piston 25 is provided with a convex portion 25a and a concave portion 25b, and the outer peripheral surface of the rotating body 3 is provided with a convex portion 3a and a concave portion 3b. The convex portions 25a, 3a and the concave portions 25b, 3b are provided in an annular shape. The concave portion 25b is sandwiched between a pair of convex portions 25a, and the concave portion 3b is sandwiched between a pair of convex portions 3a. In the first state, the convex portion 25a of the switching piston 25 and the convex portion 3a of the rotating body 3 face each other, and the gap 1b is narrowed. On the other hand, in the second state, the convex portion 25a of the switching piston 25 and the concave portion 3b of the rotating body 3 face each other, and the concave portion 25b of the switching piston 25 and the convex portion 3a of the rotating body 3 face each other, and the gap 1b is wider than in the first state.

There are multiple recesses 25b and multiple recesses 3b (two of each in this embodiment). Ports 2a and 2b are each provided in separate recesses 25b. Flow paths 31h1 and 31h2 open into separate recesses 3b.

If the sizes of the gap at the narrowest portion of gap 1b in the first and second states are h1 and h2, respectively, h2/h1 is, for example, 2 or more, preferably 5 or more, and more preferably 10 or more. This value is, for example, 2 to 1000, specifically, for example, 2, 5, 10, 20, 30, 40, 50, 100, 1000, and may be in a range between any two of the numerical values exemplified here or any greater than or equal to the numerical values exemplified here. h1 [mm] is, for example, 0.01 to 0.1, preferably 0.02 to 0.03, specifically, for example, 0.01, 0.02, 0.025, 0.03, 0.04, 0.05, 0.10, and may be in a range between any two of the numerical values exemplified here. h2 [mm] is, for example, 0.2 to 10, preferably 0.5 to 1.5, specifically, for example, 0.2, 0.5, 1, 1.5, 2, 3, 4, 5, 10, or may be in the range between any two of the values exemplified here.

2. Operation of the rotating cylinder 1 The operation of the rotating cylinder 1 will be described with reference to Figures 1 to 7. The following describes an example in which the chuck holds a workpiece by retracting the main piston 32. When the chuck holds a workpiece by advancing the main piston 32, the ports 2a and 2b that supply and discharge the working fluid are reversed, but other functions and effects are the same. Note that "retraction" of the main piston 32 means that the main piston 32 moves leftward in Figure 2.

(1) Initial State First, a state in which the chuck does not hold a workpiece and the state switching unit 22 is in the second state shown in FIG. 6B is defined as the initial state.

(2) Holding the Workpiece When moving the chuck in the direction of holding the workpiece, the state switching unit 22 puts the gap 1b into the first state shown in Fig. 6A and supplies the working fluid from the port 2a to the cylinder chamber 33a. Since the total capacity of the cylinder chambers 33a and 33b is constant, the working fluid in the cylinder chamber 33b is discharged through the port 2b and the drain port 21c by the volume of the working fluid supplied to the cylinder chamber 33a. This causes the main piston 32 to move backward. This operation is continued until the chuck holds the workpiece. During this operation, the gap 1b is in the first state, so the gap 1b is small and the amount of drainage does not increase.

(3) Switching from the first state to the second state When the workpiece is held by the chuck, the state switching unit 22 switches the gap 1b to the second state. Since the pressure retention valve 34a is provided in the flow path 31h1 communicating with the cylinder chamber 33a, the pressure of the working fluid in the cylinder chamber 33a is maintained, and the workpiece is not released from the chuck. When the spindle is rotated in this state, the rotating body 3 rotates together with the spindle. The heat generated at this time is inversely proportional to the size of the gap 1b, but since the gap 1b is large in the second state, the amount of heat generated is small, and the energy loss associated with the heat generation is small. In addition, since the amount of heat generated is small, the temperature rise of the rotating body 3 is small, and the deterioration of the machining accuracy due to the heat from the rotating body 3 being transmitted to the spindle is suppressed. The state switching by the state switching unit 22 may be performed in a state where the rotating body 3 is stopped, or may be performed while the rotating body 3 is rotating.

(4) Refreshing Operation Ideally, the pressure of the working fluid in the cylinder chamber 33a is maintained by the pressure retention valve 34a, so it is possible to keep the second state until the end of machining by the machine tool. However, in reality, the pressure of the working fluid in the cylinder chamber 33a may decrease due to leakage of the working fluid from the cylinder chamber 33a. If the pressure of the working fluid decreases, the holding force of the chuck for the workpiece decreases, so it is preferable to perform a refreshing operation to increase the working fluid from the cylinder chamber 33a before the pressure of the working fluid falls below a predetermined threshold. The refreshing operation may be performed periodically, or may be performed when it is detected that the pressure of the working fluid falls below a predetermined threshold. When the refreshing operation is performed periodically, the cycle of the refreshing operation is 0.1 to 10 minutes, preferably 0.5 to 2 minutes, and specifically, for example, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 minutes, and may be in a range between any two of the numerical values exemplified here. In the case where the pressure of the working fluid is detected to perform the refresh operation, if the pressure immediately after the gap 1b is switched to the second state is _P0 , the threshold pressure for performing the refresh operation is α× _P0 , where α is, for example, 0.50 to 0.99, and preferably 0.8 to 0.95. Specifically, α may be, for example, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, or 0.99, or may be in a range between any two of the numerical values exemplified here.

The refreshing operation can be performed by setting the gap 1b to the first state using the state switching unit 22, similar to "(2) Holding the workpiece". In the refreshing operation, a small amount of working fluid flows into the cylinder chamber 33a, increasing the pressure of the working fluid in the cylinder chamber 33a. After the pressure of the working fluid in the cylinder chamber 33a has been increased, it can be switched to the second state, similar to "(3) Switching from the first state to the second state".

The refresh operation should be performed for a time sufficient to increase the pressure of the working fluid in the cylinder chamber 33a, and the time for which the refresh operation is performed is, for example, 1 second or more. This time is, for example, 1 to 60 seconds, and specifically, for example, 1, 5, 10, 20, 30, 40, 50, or 60 seconds, and may be in a range between any two of the numerical values exemplified here, or any value greater than or equal to the number.

(5) Releasing the Workpiece When machining of the workpiece is completed, the chuck releases the workpiece by releasing its hold. When moving the chuck in the direction to release the workpiece, the state switching unit 22 sets the gap 1b to the first state, supplies the working fluid from the port 2b to the cylinder chamber 33b, and drains the working fluid in the cylinder chamber 33a through the port 2a and the drain port 21c by the volume of the working fluid supplied to the cylinder chamber 33b. This moves the main piston 32 forward. During this operation, the gap 1b is in the first state, so the gap 1b is small and the amount of drainage does not increase.

In the above embodiment, it is assumed that the pump for supplying the working fluid is operated even in the second state, but if there is no need to improve the efficiency of oiling or cooling the bearings, the pump may be stopped. In this case, the energy required for the pump operation can be reduced, making it possible to further save energy.

1: Rotating cylinder, 1a: Radial opposing portion, 1b: Gap, 2: Base, 2a: First port, 2b: Second port, 22: State switching portion, 25: Switching piston, 25a: Convex portion, 25b: Concave portion, 3: Rotating body, 3a: Convex portion, 3b: Concave portion, 31h1: First flow path, 31h2: Second flow path, 32: Main piston, 33a: First cylinder chamber, 33b: Second cylinder chamber, 34a: First pressure retention valve, 34b: Second pressure retention valve

Claims

A rotary cylinder including a base and a rotor configured to be rotatable relative to the base,
a state switching unit that can switch a gap between the base and the rotor at a radially opposed portion where the base and the rotor are radially opposed to each other between a first state and a second state;
The second state is a state in which the gap is larger than that in the first state.
2. A rotating cylinder according to claim 1,
The state switching portion includes a switching piston provided on the base at the radially opposed portion,
A rotating cylinder, the state of which is switched between a first state and a second state in accordance with the movement of the switching piston in the axial direction of the rotating body.
A rotating cylinder according to claim 2,
The switching piston is cylindrical,
An inner peripheral surface of the switching piston and an outer peripheral surface of the rotor are each provided with a convex portion and a concave portion,
In the first state, the convex portion of the switching piston and the convex portion of the rotor face each other,
A rotating cylinder, in a second state, a convex portion of the switching piston faces a concave portion of the rotating body, and a concave portion of the switching piston faces a convex portion of the rotating body.
A rotating cylinder according to any one of claims 1 to 3,
the rotor includes a rotor body, a main piston, first and second cylinder chambers, and first and second pressure retention valves;
The base includes first and second ports configured to be capable of supplying and discharging a working fluid;
the first and second ports are disposed in the radially opposing portions,
The first port and the first cylinder chamber are connected through a first flow path,
The second port and the second cylinder chamber are connected through a second flow path,
the main piston is configured to be movable by supplying and discharging the working fluid to and from the first and second cylinder chambers,
A rotary cylinder, wherein the first and second pressure retention valves are configured to be capable of retaining the pressure of the working fluid supplied into the first and second cylinder chambers, respectively.