Machine tools

Abstract

To provide a general-purpose machine tool that can also suitably perform gear grinding. [Solution] The grinding unit includes a tool spindle, a tool change mechanism for attaching and detaching tools to and from the tool spindle, a grinding wheel, and a drive mechanism for transmitting the rotation of the tool spindle to the grinding wheel and converting its rotation direction or rotation speed, and a stocker for accommodating the grinding unit, the stocker being located inside the machining chamber in which the tool spindle is located.

Description

[Technical Field]

[0001] The present invention relates to a machine tool. [Background technology]

[0002] When manufacturing a large number of gears, dedicated machine tools for gear machining, such as hobbing machines and grinding machines, are used. On the other hand, when manufacturing gears in small lots, general-purpose machine tools, such as five-axis machines and multi-tasking machines, are sometimes used (see Patent Document 1).

[0003] When machining gears with general-purpose machine tools, it is necessary to increase overall manufacturing efficiency by consolidating processes, not only for gear cutting but also for grinding the tooth surfaces, without removing the workpiece from the table or chuck.For example, if the machine is configured so that not only the gear cutting tools but also the grinding wheels can be automatically replaced on the tool spindle, it will be possible to perform both gear cutting and grinding on a single general-purpose machine tool.

[0004] However, depending on the size of the gear to be machined and the shaft configuration of the machine tool, it may be difficult to perform appropriate grinding when the tool is attached to the tool spindle via a tool holder like other cutting tools. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-168203 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in view of the above-mentioned problems, and has as its object to provide a general-purpose machine tool that can also suitably perform gear grinding. [Means for solving the problem]

[0007] The machine tool according to the present invention comprises a grinding unit having a tool spindle, a tool changing mechanism for attaching and detaching a tool to and from the tool spindle, a grinding wheel, and a drive mechanism for transmitting the rotation of the tool spindle to the grinding wheel and converting the direction or speed of rotation, and a stocker for accommodating the grinding unit, the stocker being located within a machining chamber in which the tool spindle is located. [Effects of the Invention]

[0008] The machine tool of the present invention can integrate not only the gear cutting process but also the grinding of the tooth surfaces. In addition, since it is equipped with a grinding unit that can be attached to and detached from the tool spindle, it is easy to properly grind gears of a size or shape that would be difficult to grind with a grinding wheel that can be attached directly to the tool spindle. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing the overall configuration of a machine tool. [Figure 2] FIG. 2 is a diagram showing a gear cutting operation in a state where a skiving cutter is attached to a tool spindle in a machine tool. [Figure 3] FIG. 3 is a diagram showing the cleaning operation of the end face of the tool spindle after the skiving cutter is removed from the tool spindle after gear cutting is completed in the machine tool. [Figure 4] FIG. 4 is a diagram showing the operation of phasing the workpiece and the grinding operation in a state where the grinding unit is attached to the tool spindle of a machine tool. [Figure 5] FIG. 5 is a perspective view showing a grinding unit attached to a work spindle. [Figure 6] FIG. 6 is a diagram showing the mounting end surface of the grinding unit and the tip surface of the tool spindle to which the grinding unit is mounted. [Figure 7] FIG. 7 is a diagram showing a configuration related to the coolant nozzle of the grinding unit. [Figure 8] FIG. 8 is a diagram showing a configuration for rotating the grinding wheel of the grinding unit. [Figure 9] FIG. 9 is a diagram showing a configuration for stopping the grinding wheel spindle when the belt breaks in the grinding unit. [Figure 10] FIG. 10 is a diagram showing a mechanism for detecting the rotation state of the grinding wheel spindle of the grinding unit. [Figure 11] FIG. 11 is a flowchart showing a process for determining whether or not the belt of the grinding unit is broken while the tool spindle is rotating. [Figure 12] FIG. 12 is a flowchart showing a process for determining whether or not the belt of the grinding unit is broken when the tool spindle is rotating. [Figure 13] FIG. 13 is a diagram showing a stocker in which the grinding units are stored. [Figure 14] FIG. 14 is a diagram showing the movement when the stocker is opened and the grinding unit is attached to the tool spindle. [Figure 15] FIG. 15 is a diagram showing the movement when the grinding unit is removed from the tool spindle and returned to the stocker. [Figure 16] FIG. 16 is a diagram showing a hanger unit on which the grinding unit is placed in the stocker. [Figure 17] FIG. 17 is a diagram showing a gas supply mechanism provided in the holding unit for supplying gas to the grinding unit. [Figure 18] FIG. 18 is a diagram showing an internal flow path for flowing a gas for connection confirmation that communicates when the grinding unit is placed on the holding unit. [Figure 19] FIG. 19 is a diagram showing the state in which the door is open and the position of the stocker. [Figure 20] FIG. 20 is a diagram showing a stopper mechanism that limits the movement of the openable / closable door to a half-open position that covers the lower side of the stocker. [Figure 21] FIG. 21 is a diagram of the stopper mechanism as seen from the rear side. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] The machine tool of this embodiment is a so-called general-purpose machine tool 100 as shown in Fig. 1, which is not limited to machining one type of workpiece W. More specifically, this machine tool 100 is configured to be able to perform gear cutting and grinding without removing the workpiece W to be machined that is fixed on the table. In other words, this machine tool 100 is capable of performing machining to generate at least gears, and is also configured to be able to perform cutting machining of mechanical parts other than gears.

[0012] As shown in FIGS. 1 and 2(a), machine tool 100 includes a tool spindle 1 mounted on the ceiling and a oscillating table 2 mounted in the center. Tool spindle 1 is mounted along the vertical Z-axis direction and is configured for translational machining in three axes: the horizontal X-axis (left-right direction in the drawing), the Y-axis (depth direction in the drawing), and the Z-axis direction. Oscillating table 2 is cantilevered from the rear wall of the machine interior and includes a roughly L-shaped cradle 21 mounted on the rear wall of the machine interior so as to be rotatable about the Y-axis, and a mounting table 22 mounted on the tip of cradle 21 and on which a workpiece W is placed. Mounting table 22 is mounted on cradle 21 so as to be rotatable about the Z-axis relative to cradle 21 in the basic position. In the following description, following the convention of machine tool 100, rotation about the Y-axis is also referred to as B-axis rotation, and rotation about the Z-axis is also referred to as C-axis rotation. The loading table 22 for the cradle 21 is configured to be rotatable at a predetermined rotation speed or higher that allows turning of the workpiece W attached to the loading table 22 by C-axis rotation, for example.

[0013] This machine tool 100 is configured to enable automatic tool change for so-called general-purpose tools such as end mills, skiving cutters, hob cutters, milling mills, drills, etc., on the tool spindle 1 using an automatic tool change mechanism. A machining chamber surrounded by a splash guard and an adjacent tool magazine containing a large number of tools are separated by an opening / closing shutter 31 provided at the rear left side of the rear side of the machine interior (to the left of the oscillating table 2). Furthermore, in front of the tool change opening / closing shutter 31 and on the left side of the front of the machining chamber, a stocker 5 is provided that houses a grinding unit 4 that is detachably attached to the end surface of the tool spindle 1. This grinding unit 4 includes at least a grinding wheel 42 rotatable about at least a horizontal axis, and a drive mechanism 44 that converts the direction of rotation of the tool spindle 1 about the Z axis so that the grinding wheel 42 rotates about the horizontal axis. This grinding unit 4 is larger and heavier than normal tools and large tools, and is not only inserted into the tool insertion hole of the tool spindle 1, but is also supported relative to the tool spindle 1 by a clamping mechanism provided between the end face of the tool spindle 1 and a mounting surface 41, which is the top surface of the grinding unit 4.

[0014] Here, the machining chamber of this machine tool is configured so that the upper side is longer in the depth direction than the lower side. That is, when viewed from the side, the opening and closing door provided on the front of the machine tool 100 is configured so that the upper part protrudes forward, the central part diagonally retreats from the near side to the far side, and the lower part is positioned further back than the upper part. In this way, when the opening and closing door D is opened, the operator can easily approach the oscillating table 2, making it easier to perform work such as mounting the workpiece W. In addition, the volume of the machining chamber is increased as the upper part protrudes forward.

[0015] As shown in Figure 2(b), the opening / closing shutter 31 is opened, and the double arms of the automatic tool change mechanism automatically exchange a tool taken out of the tool magazine for a tool inserted in the tool spindle 1. Figure 2(b) shows the state in which no tool is inserted in the tool spindle 1, followed by the insertion of a skiving cutter. As shown in Figure 2(c), with the skiving cutter inserted in the tool spindle 1, the tool spindle 1 is lowered downward, and the oscillating table 2 changes its position so that it is tilted at a predetermined angle around the B axis. In this state, the tool spindle 1 is rotated, and the mounting table 22 is also rotated around the C axis, bringing the skiving cutter into contact with the workpiece W, thereby cutting gears on the inner surface of the cylindrical workpiece W.

[0016] When gear cutting on the workpiece W is complete, the automatic tool change mechanism pulls the skiving cutter out of the tool spindle 1 and stores it in the tool magazine. For tool spindles 1 with nothing attached to their end faces, compressed air is blown onto the end faces of the tool spindle 1 by the air cleaning mechanism WS located at the top left rear of the back of the machining chamber, as shown in Figures 3(a) and 3(b), to remove chips, coolant, and other materials adhering to the end faces. After that, as shown in Figure 3(c), the flat cover 52 of the stocker 5 moves toward the rear of the machine, exposing the grinding unit 4 housed inside it to the interior of the machining chamber.

[0017] The tool spindle 1 is lowered onto the upper surface of the grinding unit 4 exposed from the stocker 5, and the grinding unit 4 is fixed to the end surface of the tool spindle 1. The tool spindle 1 is then removed from the stocker 5. After the grinding unit 4 is removed, the cover 52 of the stocker 5 moves forward and aligns with the main body, closing the cover. In other words, the rear end surface of the stocker 5 is positioned only in front of the oscillating table 2, preventing interference with the workpiece W even if the oscillating table 2 changes position. As shown in Figure 4(b), the grinding unit 4 is then positioned so that its tip faces the gear teeth formed by gear cutting. The table is then rotated along the C-axis, and the grinding wheel position of the grinding unit 4 is aligned with the phase of the gear being machined based on the on / off signal of the proximity sensor 43 attached to the tip of the grinding unit 4. After the phase alignment, the disk-shaped grinding wheel 42 is aligned with the center of the gear tooth root. The grinding wheel 42 is then pressed against the workpiece W, and the tool spindle 1 is moved in the Z-axis direction to grind each tooth surface.

[0018] Next, the grinding unit 4 will be described in detail with reference to Figures 5 to 12. As shown in Figure 5, the grinding unit 4 is a roughly rectangular parallelepiped unit extending in the Z-axis direction, and includes a mounting surface 41 at its base end that is attached to the end face of the tool spindle 1, a disk-shaped grinding wheel 42 that is provided at its tip end and is rotatable in a direction perpendicular to the rotation axis of the tool spindle 1, and a drive mechanism 44 that transmits the rotation of the tool spindle 1 to the grinding wheel 42. In addition, a proximity sensor 43 used to align the phase of the gear to be machined and the grinding wheel 42 is provided below the grinding wheel 42 of the grinding unit 4, with its sensor surface facing in a direction perpendicular to the axial direction of the grinding unit 4.

[0019] As shown in Figure 6, a detachable structure is formed between the top of the grinding unit 4 and the end face of the tool spindle 1. The detachable structure includes an insertion structure, a clamping mechanism, a positioning mechanism, a power supply mechanism, and a coolant circuit connection mechanism. The insertion structure is similar to a typical tool holder and insertion hole of the tool spindle 1, consisting of a tool holder portion located in the center of the top surface of the grinding unit 4 and an insertion hole of the tool spindle 1. The clamping mechanism is located radially outward of the insertion structure. An engagement protrusion on the grinding unit 4 is inserted into an engagement hole located on the outer periphery of the end face of the tool spindle 1, and the engagement protrusion and engagement hole are clamped and fixed by a mechanism such as hydraulics. The positioning mechanism is formed by four sets of positioning protrusions and positioning holes, which are fitted together to align the insertion structure and the clamping mechanism. Power supplied to the machine tool 100 from a power supply device on the tool spindle 1 is wirelessly transmitted to the power receiver of the grinding unit 4. The power supply mechanism is located on the side opposite the grinding wheel 42 so that it is not exposed to chips generated during grinding or coolant that splashes around during grinding. As shown in Figure 7, the coolant circuit connection mechanism introduces coolant supplied from the tool spindle 1 into the grinding unit 4 and supplies it to the location being searched from nozzles provided around the grinding wheel 42. In addition, electrical connections are also made for the exchange of various signals, etc.

[0020] Next, the drive mechanism 44 of the grinding unit 4 will be described with reference to FIG. 8. The drive mechanism 44 includes a vertical shaft with a drive bevel gear directly connected to the tool holder inserted into the tool spindle 1; a horizontally extending drive shaft perpendicular to the vertical axis and with a driven bevel gear at its end; a grinding wheel spindle located further forward than the drive shaft and parallel to the drive shaft; and a loop-shaped belt connecting the drive shaft and the grinding wheel spindle. The drive shaft has a driven bevel gear at one end and a large-diameter pulley at the other end. The grinding wheel spindle has a small-diameter pulley at one end and a disc-shaped detector at the other end for measuring the rotation speed. A disc-shaped grinding wheel 42 is mounted in the center, penetrating the face plate. A drive belt is wound between the large-diameter pulley and the small-diameter pulley. The inner surface of the belt is formed with concave and convex structures that match the concave and convex structures formed on the outer periphery of each pulley. That is, the rotation of the tool spindle 1 around the Z axis is converted into a rotation about the Y axis direction in the grinding wheel 42 by the drive mechanism 44. In addition, the grinding wheel 42 is located on a drive shaft provided with a small diameter pulley, and is therefore configured to be rotatable at a higher rotation speed than the rotation speed achieved by the tool spindle 1.

[0021] As shown in Figure 9, the grinding unit 4 is belt-driven, and a safety mechanism 4S is provided to prevent the grinding wheel 42 from continuing to rotate due to inertia even if the belt breaks. This safety mechanism 4S is a narrow section between a guide that restricts the movement of the belt and a pressing mechanism that presses the belt against the guide. If the belt breaks, the belt will become stuck in this narrow section, causing the grinding wheel spindle to stop rotating.

[0022] The grinding unit 4 also includes a rotation detector for detecting the rotation of the grinding wheel 42. This rotation detector is configured to obtain the rotation count or rotation speed based on the output of a sensor element attached to one end of the grinding wheel spindle and a proximity switch that detects the approach or separation of the sensor element. Power for operating this rotation detector and signals from the CNC and other components of the machine tool 100 are exchanged via a wireless power supply mechanism. A transparent cover is provided on the portion of the grinding wheel spindle facing its end so that its rotation can be visually confirmed from outside the grinding unit 4. The rotation detector detects the rotation of the drive shaft, and based on the results, determines whether the belt is broken. If the belt is possibly broken, an alarm is sounded in the machine tool 100. If an alarm is sounded, the machine is brought to a stop. After the belt breaks, the door D may be prohibited from opening until a period of time has passed during which the grinding wheel 42 is considered to have completely stopped. The processing procedure for determining whether or not to issue an alarm by the rotation detector is as shown in FIG. 11 when the tool spindle 1 is rotating, and as shown in FIG. 12 when a command to stop the rotation of the grinding wheel 42 is issued and the tool spindle 1 is stopped.

[0023] Next, the stocker 5 that houses the grinding unit 4 will be described with reference to FIG. 13. The stocker 5 is provided within the machining chamber of the machine tool 100. That is, while normal tools are stored in a tool magazine located outside the machining chamber, the grinding unit 4 is located within the machining chamber together with the tool spindle 1 and oscillating table 2. More specifically, the stocker 5 is located in the center of the door D, which slopes downward from the front to the rear. That is, a portion of the stocker 5 is located in the bay window portion of the door D. Furthermore, when the grinding unit 4 is housed in the stocker 5, the grinding unit 4 and the cover 52 are located forward of the tip of the cradle 21 of the oscillating table 2. In addition, the stocker 5 is provided on the door D side in the machining chamber and is located on the front side of the machine tool 100 alongside the opening / closing shutter 31 of the automatic tool changer. Stocker 5 is fixed to a partition wall and includes a main body 51 having a space formed therein for accommodating grinding unit 4, and a cover 52 provided so as to be movable toward and away from main body 51 in the front-to-rear direction (Y-axis direction) of machine tool 100. The procedure for removing grinding unit 4 from stocker 5 by tool spindle 1 is shown in Fig. 14, and the procedure for removing grinding unit 4 from tool spindle 1 and storing it back in stocker 5 is shown in Fig. 15.

[0024] Grinding unit 4 is held in a state in which it is placed on holding mechanism 53 in stocker 5. Holding mechanism 53 is configured to be able to move in an expandable and contractible manner in the front-to-rear direction of machine tool 100, and has lid body 52 attached to one end of holding mechanism 53. When grinding unit 4 is moved from inside main body 51 to the rear outside, lid body 52 also moves rearward in conjunction with it.

[0025] Whether the end face of the tool spindle 1 is seated on the mounting surface 41 of the grinding unit 4 mounted on the holding mechanism 53 and in close contact is determined based on the pressure of air supplied from the holding mechanism 53. Specifically, as shown in FIG. 17 , an air supply mechanism for circulating air is provided inside the arm of the holding mechanism 53 that contacts the lower mounting surface of the grinding unit 4. Also, as shown in FIG. 18 , an internal flow path leading to the mounting surface 41 is provided inside the bracket on the upper surface of the inspection unit. The air supply mechanism in the holding mechanism 53 communicates with the internal flow path of the grinding unit 4, supplying air to the mounting surface 41. When the end face of the tool spindle 1 is seated on the mounting surface 41 of the grinding unit 4 and sufficient contact is achieved, pressure rises because there is no escape route for the air. If the pressure rise turns on a pressure switch provided in the air supply mechanism or a flow rate connected to it, the tool spindle 1 is permitted to rise. Conversely, if the pressure switch remains off despite air being supplied, an alarm is sounded, and the machine is stopped, for example.

[0026] As shown in FIG. 19, which details the door D and its surrounding mechanisms, a central portion of the door D that slopes downward is located below the stocker 5. Also, as shown in FIGS. 20 and 21, a locking mechanism is provided on the left side of the door D to limit its opening. When the locking mechanism is engaged, the left side of the door D cannot be fully opened, and can only be opened approximately halfway. In this way, even when the door D is open, a portion of the door D is always located below the stocker 5. This allows the center of the door D to function as an oil pan, preventing coolant and other substances adhering to the stocker 5 or grinding unit 4 from dripping outside the machine tool 100 and soiling the factory floor, etc. Note that by releasing the locking mechanism, the left side of the door D can also be fully opened as needed.

[0027] As described above, according to the machine tool 100 of this embodiment, the grinding unit 4 can be attached to the end face of the tool spindle 1, for example, to rotate the grinding wheel 42 in a direction different from that of the tool spindle 1 and increase the rotation speed, so that gears and internal gears of various sizes can be suitably ground.

[0028] Furthermore, grinding units 4 that cannot be accommodated in the tool magazine are stored in stockers 5 provided in the machining chamber, making it possible to use grinding units 4 suitable for the gears to be machined without being restricted by the restrictions of the tool magazine. This makes it easy to appropriately handle even small lots of gears.

[0029] The stocker 5 that houses the grinding unit 4 is provided adjacent to the opening / closing shutter 31 for automatic tool change, which minimizes the travel distance required to remove a tool inserted in the tool spindle 1 and then replace it with the grinding unit 4, thereby shortening the time it takes to start grinding with the grinding unit 4. In addition, when the grinding unit 4 is exposed inside the stocker 5, the lid 52 moves to the front of the opening / closing shutter 31 for tool change, but when closed, the lid 52 and the opening / closing shutter 31 do not overlap. Since normal tools and the grinding unit are not used at the same time, it is possible to make effective use of the space within the machining chamber without affecting each other's tool change operations.

[0030] In addition, various modifications of the embodiment may be made as long as they do not deviate from the spirit of the present invention. [Explanation of symbols]

[0031] 100...Machine tools 1...Tool spindle 2. Swing table 31 Open / close shutter 4 Grinding unit 5 Stocker

Claims

1. A tool spindle; a tool change mechanism that attaches and detaches a tool to and from the tool spindle; a grinding unit including a grinding wheel and a drive mechanism that transmits the rotation of the tool spindle to the grinding wheel and converts the direction or speed of rotation of the grinding wheel; a stocker that accommodates the grinding unit; a tool magazine arranged outside the processing chamber and accommodating tools other than the grinding wheel; an opening and closing door provided on the front of the processing chamber, The tool changing mechanism includes: an opening / closing shutter that separates the tool magazine from the machining chamber and opens and closes to transfer tools between the tool spindle and the tool magazine; The machine tool is characterized in that the stocker is arranged on the same side in the left-right direction as seen from the opening / closing shutter and the opening / closing door in the machining chamber in which the tool spindle is arranged.

2. 2. The machine tool according to claim 1, The machine tool is characterized in that the stocker is provided adjacent to the opening / closing shutter.

3. 2. The machine tool according to claim 1, The stocker includes: a main body that houses the grinding unit; a cover that is provided so as to be able to approach and move away from the main body portion and that is switchable between a closed state in which the stocker accommodates the grinding unit and an open state in which the grinding unit is exposed to the processing chamber by opening and closing the main body portion; The machine tool, characterized in that the cover is located outside the opening / closing shutter in the closed state, and at least a portion of the cover is located in front of the opening / closing shutter in the open state.

4. 2. The machine tool according to claim 1, The machine tool further comprises: an opening / closing door provided on the front of the machine tool and separating the machining chamber from the outside; The machine tool is characterized in that the stocker is provided closer to the opening / closing door than the opening / closing shutter.

5. 2. The machine tool according to claim 1, The grinding unit comprises: a mounting surface attached to the tool spindle; The stocker includes: a main body that houses the grinding unit; a cover that is provided so as to be able to approach and move away from the main body portion and that can be switched between a closed state in which the stocker accommodates the grinding unit and an open state in which the grinding unit is exposed to the inside of the processing chamber by opening and closing the main body portion; a holding mechanism that moves in an expanding and contracting manner in conjunction with the cover body and holds the grinding unit, the holding mechanism supports the grinding unit with the attachment surface facing upward in the open state; The machine tool is characterized in that the tool spindle approaches a mounting surface of the grinding unit from above and is attached to the grinding unit.

6. 2. The machine tool according to claim 1, The stocker includes: a main body that houses the grinding unit; a cover that is provided so as to be able to approach and move away from the main body portion and that can be switched between a closed state in which the stocker accommodates the grinding unit and an open state in which the grinding unit is exposed to the inside of the processing chamber by opening and closing the main body portion; a holding mechanism that holds the grinding unit and moves in conjunction with the cover body to position the grinding unit inside the main body in the closed state and to position the grinding unit outside the main body in the open state.

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