Rotary machine

Abstract

To achieve intrusion restriction of chips, energy saving and noise suppression, with a small amount of air supply.SOLUTION: A rotary machine comprises: a table 4 disposed inside a cylindrical opening via a narrow slit 33; an annular seal material 36 closing the narrow slit 33; and an air supply passage 60 for supplying air to an annular space 43 existing inside the annular seal material. In the annular seal material 36, its base part 38 is fitted to an opening 13, such that a seal portion 85 contacts a slide surface 41 of the table 4 in a state where a tip side of a lip part 39 of the annular seal material is directed to the outside of the narrow slit 33. During non-supply of air, the whole seal portion 85 is in surface contact with the slide surface 41 at a prescribed contact width Ws, and in a state where at least a part of the seal portion 85 is in surface contact with the slide surface 41 within a range of the contact width Ws, in accordance with the supply of the air, the air blows out from the remaining part of the seal portion 85.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The technology disclosed relates to rotating equipment, such as an indexing device, that supports an object to be processed in a rotatable state during cutting processing, and in particular to a technology that is suitable for use when the cutting chips (also called swarf or shavings) generated during cutting processing are in powder form. [Background technology]

[0002] During cutting, chips scatter around the object being cut. If chips get into the rotating parts of rotating equipment, it can cause the equipment to break down. For this reason, the rotating parts are usually sealed with a sealant to prevent chips from getting in.

[0003] The present inventor has also provided prior art related to the technology disclosed herein (Patent Documents 1 and 2).

[0004] Patent Document 1 discloses a rotating device equipped with a disk-shaped table. In order to seal a gap around the table, two ring-shaped seal materials are installed inside and outside the gap via an annular space.

[0005] By supplying air to the annular space, air pressure acts on the outer seal in the opening direction and on the inner seal in the closing direction. This prevents chips from entering and suppresses lubricating oil leakage by blowing air.

[0006] In the rotating device of Patent Document 1, air is supplied to the annular space from one point. This causes local pressure differences, which can lead to problems such as reduced sealing performance. In the rotating device of Patent Document 2, air is supplied evenly from multiple points in the circumferential direction, making it possible to effectively suppress the pressure differences.

[0007] Various shapes of chips are recognized depending on the cutting conditions, cutting materials, etc. However, most chips have a unique shape that curls in a spiral shape, although the length and size differ (for example, Non-Patent Document 1). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2019-19848 A [Patent Document 2] JP 2020-151823 A [Non-patent literature]

[0009] [Non-Patent Document 1] Kazuo Nakayama, Precision Machinery, Vol. 42, No. 493, pp. 74-80, 1976 Summary of the Invention [Problem to be solved by the invention]

[0010] Because chips have the specific shape described above, even if air is blown out from the sealed area, their ends may get caught on the tip of the sealing material that is in contact with the rotating part. If the table rotates in this state, the chips may get caught and enter the rotating equipment.

[0011] Therefore, in the rotating devices of Patent Document 1 and Patent Document 2, in order to prevent the intrusion of chips, it was necessary to blow air from the sealed area with a certain degree of force so that the chips would not get caught on the tip of the sealing material. Accordingly, the air pressure at the sealed area had to be kept high. For example, in the rotating device of Patent Document 2, it is said that it is preferable to adjust the air pressure to 0.05 MPa, that is, about 50 kPa (paragraph 0049 of the specification).

[0012] Therefore, the amount of air consumed is inevitably large, and there is room for improvement from the viewpoint of energy saving. In addition, there are cases where abnormal noise occurs when air is blown out, and there is also room for improvement from the viewpoint of noise. This is also the main cause of the local pressure difference occurring in the rotating equipment of Patent Document 1.

[0013] An object of the disclosed technology is to provide a rotating device that can effectively prevent chips from entering with a small amount of air supply, thereby achieving energy savings and noise reduction. [Means for solving the problem]

[0014] The disclosed technology relates to a rotating device for supporting a workpiece during cutting processing.

[0015] The rotating device includes a housing having a cylindrical opening on the front side, a table rotatably arranged inside the opening through a narrow gap, an annular seal material for closing the narrow gap, and an air supply passage for supplying air at a predetermined pressure to an annular space inside the annular seal material. The annular seal material has an annular base and an elastically deformable lip portion extending from the base and having a predetermined sealing portion at its tip.

[0016] The base is attached to the opening and to one of the sliding surfaces of the table with the tip side of the lip portion facing outward from the narrow gap, and when air is not supplied to the annular space, the entire sealing area is set to be in surface contact with the sliding surface at a predetermined contact width, and when air is supplied to the annular space, the air is set to blow out from the remainder of the sealing area with at least a portion of the sealing area in surface contact with the sliding surface within the range of the contact width.

[0017] Preferably, the pressure of the air in the annular space is set to 5 kPa or more, and the amount of the air supplied is set to 12 L / min or less.

[0018] Preferably, a throttle valve is provided in the air supply passage, and the pressure and supply amount of the air are set by the amount of throttling of the throttle valve.

[0019] Preferably, the sealing portion comprises a curved surface or a flat surface formed by chamfering a corner of a tip portion of the lip portion.

[0020] The rotating device is preferably used for cutting processing that generates powder-like chips without curled portions. Effect of the Invention

[0021] According to a rotating device to which the disclosed technology is applied, the amount of air supply required to prevent chips from entering the rotating device can be reduced, thereby achieving energy savings and noise reduction. [Brief description of the drawings]

[0022] [Figure 1] FIG. 2 is a schematic perspective view showing the appearance of the indexing device according to the embodiment. [Diagram 2] 2 is a schematic cross-sectional view taken along the direction of the arrow II in FIG. 1. [Diagram 3] 2. FIG. 2 is a schematic cross-sectional view taken along the line II-II in FIG. [Figure 4] FIG. 13 is a diagram for explaining powder-like chips. [Diagram 5] FIG. 13 is an enlarged view of the front seal structure when air is not supplied. [Figure 6] 13A and 13B are diagrams for explaining a sealing state when air is supplied to the annular space. [Figure 7] FIG. 13 is a diagram for explaining wear caused by powdery chips. [Figure 8] 1 is a table summarizing test results regarding air flow rate settings. [Figure 9] 1 is a table summarizing test results regarding air flow rate settings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of the disclosed technology will be described in detail with reference to the drawings. However, the following description is essentially merely exemplary. The term "axial direction" used in the description means the direction in which the rotation axis J extends. Similarly, the term "circumferential direction" means the circumferential direction centered on the rotation axis J, and the term "radial direction" means the radial or diametric direction centered on the rotation axis J. The term "front" means the processing side where cutting is performed, and the term "rear" means the opposite side.

[0024] <Overall structure of rotating equipment> Fig. 1 shows an indexing device 1 as an example of a rotating device to which the disclosed technology is applied. Fig. 2 shows a schematic cross-sectional view of the indexing device 1 as viewed from the direction of the arrow line II in Fig. 1. Fig. 3 shows a schematic cross-sectional view of the indexing device 1 as viewed from the direction of the arrow line II-II in Fig. 2.

[0025] The indexing device 1 is used to support a workpiece (workpiece W) directly or indirectly via a chuck during cutting, as shown in Fig. 1. The indexing device 1 is configured to rotate the workpiece W around a rotation axis J according to the machining state of the workpiece W, and to position the workpiece W at a predetermined rotation angle with high precision.

[0026] Although details will be described later, this indexing device 1 is configured for cutting processes that mainly generate powder-like chips without curls (herein referred to as "powdery chips"), unlike conventional cutting processes that generate chips (spiral chips with curled parts). It is designed to effectively prevent the intrusion of powdery chips with a small amount of air supply, thereby realizing energy saving and noise reduction.

[0027] The indexing device 1 is roughly composed of a housing 2, a spindle 3, a table 4, a clamp 5, a box 6, a motor 7, and the like.

[0028] The housing 2 is composed of a main body 10, a front cover 11, a rear cover 12, etc. The main body 10 is formed with a storage chamber 10a that penetrates in the front-rear direction. The front cover 11 is attached to the front side of the main body 10 so as to close a circular front opening that opens to the front side of the storage chamber 10a. The rear cover 12 is attached to the rear side of the main body 10 so as to close a circular rear opening that opens to the rear side of the storage chamber 10a.

[0029] The front cover portion 11 is made of an annular member having a cylindrical opening (front opening 13). The front cover portion 11 is composed of a first front cover portion 11a located on the rear side in the axial direction and a second front cover portion 11b located on the front side in the axial direction. The first front cover portion 11a is formed with a plurality of first bolt holes 14 penetrating in the axial direction at a plurality of positions in the circumferential direction. The second front cover portion 11b is formed with a plurality of second bolt holes 15 so as to overlap with each of the first bolt holes 14.

[0030] An annular fitting recess 16 is formed around the front opening of the main body 10. A plurality of bolt shaft holes 17 are formed in the fitting recess 16 so as to overlap with each of the first bolt holes 14. The first front cover portion 11a is fitted into the fitting recess 16 with the second front cover portion 11b overlapping the front surface of the first front cover portion 11a.

[0031] Then, first bolts 18 are inserted into the first bolt holes 14 and the second bolt holes 15, and the first bolts 18 are fastened to the bolt shaft holes 17, thereby assembling the front cover 11 to the front side of the main body 10. In this way, a front opening 13 is provided on the front side of the housing 2.

[0032] The front opening 13 is configured so that its center is substantially aligned with the storage chamber 10a. A table 4 is rotatably disposed inside the front opening 13. The internal structure of the front cover 11 will be described later.

[0033] An annular bearing 19 is disposed at the front side of the accommodation chamber 10a. The bearing 19 has an outer ring portion 19a and an inner ring portion 19b that rotate freely relative to each other. The bearing 19 is assembled to the housing 2 by sandwiching the outer ring portion 19a between the main body portion 10 and the front cover portion 11.

[0034] The spindle 3 is made of a multi-stage cylindrical member. The table 4 is made of a disk-shaped member with an outer diameter slightly smaller than the inner diameter of the front opening 13. The table 4 is attached to the spindle 3 by fastening it to the front surface of the spindle 3 with a plurality of second bolts 22. The table 4 is exposed to the front surface of the housing 2 through the front opening 13. The workpiece W, chuck, etc. are attached to the exposed front surface of the table 4, as described above.

[0035] By assembling the table 4 to the spindle 3, the inner ring portion 19b of the bearing 19 is sandwiched between the spindle 3 and the table 4. As a result, the spindle 3 and the table 4 are journaled to the housing 2 via the bearing 19 and are rotatable about the rotation axis J.

[0036] An oil tank 23 for storing lubricating oil is provided in the lower part of the accommodation chamber 10a in the middle in the front-rear direction. By storing lubricating oil in the oil tank 23, the lubricating oil is constantly supplied to the bearing 19.

[0037] The rear lid portion 12 is made of an annular member having a cylindrical opening (rear opening 25). The rear lid portion 12 is composed of a first rear lid portion 12a located on the rear side in the axial direction and a second rear lid portion 12b located on the front side in the axial direction. The first rear lid portion 12a is integrally assembled to the main body portion 10 by fastening it with a third bolt 26.

[0038] The first rear lid portion 12a is provided with a bearing portion 27 that rotatably supports the rear portion of the spindle 3. The first rear lid portion 12a is also provided with a rear air supply passage 70 and the like, which will be described later.

[0039] The rear lid portion 12 constitutes the clamp 5. Specifically, the first rear lid portion 12a constitutes a cylinder, and the second rear lid portion 12b constitutes a piston.

[0040] An annular sliding recess 30 is formed on the front surface of the first rear lid portion 12a. The annular second rear lid portion 12b is slidably fitted into the sliding recess 30. As a result, a sealed operating chamber 31 is provided between the first rear lid portion 12a and the second rear lid portion 12b. A predetermined air pressure can be supplied to the operating chamber 31 from the box 6.

[0041] Although not shown, the housing chamber 10a houses a plurality of sliding disks arranged in the axial direction so as to be movable toward and away from each other. The second rear cover portion 12b is connected to the spindle 3 via the plurality of sliding disks. The second rear cover portion 12b is also biased rearward by a coil spring or the like.

[0042] As a result, when air pressure is not supplied to the operating chamber 31, the second rear cover portion 12b is pressed backward, the sliding discs are separated from each other, and the spindle 3 and table 4 are in a rotatable state. On the other hand, when air pressure is supplied to the operating chamber 31, the second rear cover portion 12b is pushed forward, the sliding discs are pressed against each other, and the spindle 3 and table 4 are fixed so that they cannot rotate. In other words, the table 4 is positioned at a predetermined angle.

[0043] The box 6 is a box-shaped container and is attached to one side of the housing 2. A motor 7 is housed inside the box 6. The motor 7 is connected to the spindle 3 via a gear (not shown), and the spindle 3 and the table 4 are rotated by the drive of the motor 7.

[0044] <Seal structure> There is a gap (front gap 33) between the rotating table 4 and the non-rotating front opening 13. Similarly, there is a gap (rear gap 34) between the rear end of the rotating spindle 3 and the non-rotating rear opening 25. To close these gaps, sealing structures are provided at the front and rear of the indexing device 1.

[0045] In the case of the indexing device 1, the front side thereof supporting the workpiece W is particularly prone to being exposed to chips generated during cutting. Therefore, it is necessary to prevent the chips from entering the accommodation chamber 10a through the front narrow gap 33 in particular, and the front seal structure is important.

[0046] Sealing with a high contact pressure oil seal or face seal can effectively prevent the intrusion of cutting chips. However, because the contact pressure is high, these have the problem of being prone to heat generation and wear due to friction at the contact points. On the other hand, sealing with a low contact pressure sealing material (for example, a springless oil seal or V-ring) reduces heat generation and wear at the contact points because of the low contact pressure.

[0047] However, this reduces the sealing performance, making it easier for chips to get in. Therefore, this indexing device 1 is configured to use air to effectively prevent chips (powders) from getting in even with a sealing material with low contact pressure.

[0048] (Sealing material) A front annular seal 36 is attached between the front cover 11 and the table 4 to close the front narrow gap 33, primarily for the purpose of preventing chips from entering. Similarly, a rear annular seal 37 is attached between the rear cover 12 and the spindle 3 to close the rear narrow gap 34 (these are collectively referred to as annular seals 36, 37).

[0049] These annular seals 36 and 37 are both low contact pressure seals (for example, springless oil seals, V-rings, etc.) The annular seals 36 and 37 are made of an elastic material that has excellent oil resistance, abrasion resistance, etc., such as nitrile rubber.

[0050] The annular seal members 36, 37 have an annular base portion 38 and an elastically deformable lip portion 39 extending from the base portion 38 (see FIG. 5). The lip portion 39 has a truncated cone shape and is inclined so that the inner diameter becomes smaller toward the tip side.

[0051] The rear surface of the second front cover portion 11b has a radially inner edge provided with a front stepped groove portion 40 that is recessed into an annular shape. The base portion 38 is press-fitted into the front stepped groove portion 40 with the tip side of the lip portion 39 facing the front side, which is outside the front narrow gap 33. The tip portion of the lip portion 39 has a predetermined seal portion 85, which will be described later, that is in contact with the outer circumferential surface of the table 4 (sliding surface 41).

[0052] As a result, the front annular seal 36 is attached so as to close the front narrow gap 33. Since the front step groove portion 40 is provided in the second front lid portion 11b, a front annular space 43 is formed inside the front annular seal 36, extending circumferentially along the front annular seal 36 in a sealed state.

[0053] The rear surface of the first rear cover portion 12a has a radially inner edge provided with a rear step groove portion 45 that is recessed into an annular shape. The base portion 38 is press-fitted into the rear step groove portion 45 with the tip side of the lip portion 39 facing the rear side, which is outside the rear narrow gap 34. The tip portion of the lip portion 39 has a predetermined seal portion 85, which will be described later, that comes into contact with the outer circumferential surface (sliding surface 46) of the spindle 3.

[0054] As a result, the rear annular seal 37 is attached so as to close the rear narrow gap 34. Since the first rear lid portion 12a is provided with the rear step groove portion 45, a rear annular space 48 is formed inside the rear annular seal 37, extending in the circumferential direction along the rear annular seal 37 in a sealed state (together with the front annular space 43, these are collectively referred to as annular spaces 43, 48).

[0055] A front second annular seal 50 is also attached between the front cover 11 and the table 4, mainly for the purpose of suppressing leakage of lubricating oil. Similarly, a rear second annular seal 53 is also attached between the rear cover 12 and the spindle 3 (these are also collectively referred to as the second annular seals 50, 53).

[0056] Specifically, a front annular groove 51 having a rectangular cross section is formed on the inner peripheral surface of the first front cover portion 11a, which faces the outer peripheral surface of the table 4 via a small gap. A known seal material having a substantially X-shaped cross section (a so-called X-ring) is attached to the front annular groove 51 as the front second annular seal material 50.

[0057] Similarly, a rear annular groove 52 having a rectangular cross section is formed on the inner peripheral surface of the first rear cover portion 12a, which faces the outer peripheral surface of the spindle 3 with a small gap therebetween. An X-ring is attached to the rear annular groove 52 as a rear second annular seal material 53.

[0058] The ends of the second annular seals 50, 53 slide against the outer circumferential surfaces of the table 4 and the spindle 3, thereby sealing minute gaps to prevent leakage of lubricating oil. If there is no need to prevent leakage of lubricating oil, the second annular seals 50, 53 are not essential and may be replaced with a V-ring or other device that prevents air leakage.

[0059] (Air supply passage) An air supply passage is formed in the housing 2 to supply air at a predetermined pressure to the annular spaces 43, 48. By supplying air to the annular spaces 43, 48, the annular seals 36, 37 are pressurized from the inside. As a result, even if the contact pressure of the annular seals 36, 37 is low, the difference in pressure between the inside and outside ensures sealing performance.

[0060] Furthermore, when the air pressure exceeds a certain level, the lip portion 39 is pushed up and air is blown out. Therefore, chips can be blown away and the intrusion of chips can be suppressed. Since the contact pressure of the lip portion 39 is low, heat generation can be effectively reduced. Wear can also be suppressed, improving durability.

[0061] 2 and 3 show an air supply passage (front air supply passage 60) that supplies air to the front annular space 43. The front air supply passage 60 is composed of a front upstream passage 61, a front downstream passage 62, and the like.

[0062] A first throttle valve 64, which can set the amount of air supply by adjusting the amount of throttling, is installed on the upper part of the main body 10. An air supply pipe 65, which is connected to an air supply source (not shown) such as a compressor, is connected to the first throttle valve 64. Air may be supplied to the first throttle valve 64 by branching off from a path that supplies air pressure to the working chamber 31.

[0063] The front upstream passage 61 is a thin hole formed in the main body 10, and is formed by cutting the main body 10 with a drill or the like. The front upstream passage 61 is bent in an L shape, and the upstream end of the front upstream passage 61 opens into the upper part of the main body 10 and is connected to the first throttle valve 64. The downstream end of the front upstream passage 61 opens into the joint between the main body 10 and the first front lid portion 11a.

[0064] A relay recess 67 is formed at the joint portion of the first front lid portion 11a with the main body portion 10. The front downstream passage 62 is a thin hole formed in the first front lid portion 11a, and is formed by cutting the first front lid portion 11a with a drill or the like. The front downstream passage 62 is bent in a Z shape, and the upstream end of the front downstream passage 62 opens into the relay recess 67.

[0065] The front upstream passage 61 and the front downstream passage 62 communicate with each other via the relay recess 67. The downstream end of the front downstream passage 62 opens to the front surface of the first front lid portion 11a and communicates with the front annular space 43.

[0066] Therefore, air introduced from the air supply pipe 65 is supplied to the front annular space 43 through the front upstream passage 61, the relay recess 67, and the front downstream passage 62, as shown by arrows A1 to A3 in FIGS.

[0067] Similarly, an air supply passage (rear air supply passage 70) that supplies air to the rear annular space 48 is formed in the main body 10 and the first rear lid portion 12a. The rear air supply passage 70 is made up of a rear upstream passage 71, a rear downstream passage 72, etc.

[0068] A second throttle valve 74 is provided on the upper part of the main body 10. The rear upstream passage 71 is made of a thin hole bent in an L shape in the main body 10. The upstream end of the rear upstream passage 71 is connected to the second throttle valve 74. A rear relay recess 75 is formed at the joint portion of the main body 10 with the first rear lid portion 12a, and the downstream end of the rear upstream passage 71 opens into the rear relay recess 75.

[0069] The rear downstream passage 72 is a thin hole bent in a Z shape in the first rear lid portion 12a. The upstream end of the rear downstream passage 72 opens at the joint between the main body portion 10 and the first rear lid portion 12a, and the rear upstream passage 71 and the rear downstream passage 72 communicate with each other via the rear relay recess 75. The downstream end of the rear downstream passage 72 opens at the inner circumferential surface of the first rear lid portion 12a, and communicates with the rear annular space 48.

[0070] Therefore, the air introduced from the second throttle valve 74 is supplied to the rear annular space 48 through the rear upstream passage 71, the rear relay recess 75, and the rear downstream passage 72, as shown by arrows A4 and A5 in FIG.

[0071] (Chips and their intrusion prevention) As described above, the indexing device 1 is configured for cutting processing that generates powdery chips. Generally, a metallic ductile material is used for the workpiece W, and therefore, during cutting processing, unique spiral chips having curled portions (so-called chips) are generated.

[0072] In contrast, in recent years, brittle materials such as glass, ceramics, silicon, and sintered metals have come to be used as cutting workpieces W. When cutting workpieces W made of such brittle materials, powder-like chips (powder chips) are generated, unlike conventional chips.

[0073] Figure 4 shows an example of powdered chips along with conventional chips. As shown in (b) of Figure 4, conventional chips have a distinctive curled shape and are generally relatively large in size. In contrast, as shown in (a) of Figure 4, powdered chips have a powdery appearance and are smaller than conventional chips.

[0074] Powdered chips are fine fragments that peel off from the workpiece W during cutting, and have a fragmented shape without curled portions. Their particle size (maximum diameter) is, for example, 1 μm or more and 1 mm or less. Because they are fragments, the variation in particle size is also relatively small. For example, in the case of powdered chips, at least 90% of the total amount falls within the range of 1 mm or less. Therefore, powdered chips can be distinguished from conventional chips based on their shape and size.

[0075] When the chips generated during cutting are in powder form, there is no risk of them getting caught in the annular seal, as with conventional chips. Therefore, there is no need to blow air with a strong force to prevent the chips from entering, as in the conventional method. From the viewpoint of energy saving and noise reduction, it is preferable to reduce the amount of air supply as much as possible.

[0076] Therefore, initially, we thought that if the air pressure in the annular spaces 43, 48 was kept higher than the outside air pressure, i.e., if it was kept at positive pressure, we could ensure airtightness with a minimum amount of air supply and also suppress the intrusion of powdered chips.

[0077] However, in such a case, the powder chips adhere to and accumulate on the sliding surfaces 41, 46, and the agglomerates cause partial wear of the sliding surfaces 41, 46. That is, when a depression is formed in the sliding surfaces 41, 46 due to wear, the powder chips enter the depression and accumulate to form agglomerates.

[0078] This accelerates wear, and narrow, deep recesses H are formed from the radially outer side of the sliding surfaces 41, 46 (see FIG. 7). The locations where the recesses occur in the circumferential direction are not specific and are not uniform. Therefore, wear is accelerated in the areas of the sliding surfaces 41, 46 that are unevenly distributed in the circumferential direction.

[0079] Furthermore, when the lip portion 39 is in line contact, the contact pressure is high, and therefore the frictional force generated between the sliding contact surfaces 41, 46 during rotation is also large, which further accelerates uneven wear.

[0080] Therefore, in this indexing device 1, the shape of the seal area 85 provided at the tip of the lip portion 39 and the amount of air supply are set to meet specified conditions so that the amount of air supply can be kept to a minimum necessary from the standpoint of energy saving, while simultaneously suppressing the intrusion of powdery chips and suppressing wear.

[0081] Specifically, when air is not supplied to the annular space, the entire sealing portion 85 is set to be in surface contact with the sliding surfaces 41, 46 at a predetermined contact width Ws, and when air is supplied to the annular space, air is blown out from the remainder of the sealing portion 85 while at least a portion of the sealing portion 85 is in surface contact with the sliding surfaces 41, 46 within the range of the above-mentioned contact width Ws.

[0082] Specifically, based on the test results described later, it is advisable to set the air pressure in the annular space to 5 kPa or more and the air supply rate to 12 L / min or less. It is more preferable to set the air supply rate to 5 L / min or less.

[0083] 5 shows an enlarged view of the front seal structure. Fig. 5 shows a state in which no air is supplied, and the air pressure in the front annular space 43 is the same as the external air pressure P0 of the indexing device 1.

[0084] A minute step 80 is provided on the radially outer edge of the front surface of the table 4. A minute covering portion 81 is provided on the radially inner edge of the front surface of the second front cover portion 11b, covering this minute step 80. A minute bent gap 82 that constitutes a labyrinth seal is formed between the minute step 80 and the minute covering portion 81.

[0085] The front end portion of the front narrow gap 33 is formed by this bent gap 82. Because the front step groove portion 40 is connected to the minute covering portion 81, the tip portion of the lip portion 39 of the front annular seal material 36 is located near the bent gap 82. By chamfering the corners of the tip portion of the lip portion 39, a portion (seal portion 85) that comes into surface contact with the outer circumferential surface (sliding surface 41) of the table 4 at a predetermined contact width Ws is provided. Therefore, an effective seal portion 85 can be formed extremely simply.

[0086] The cross-sectional shape of the seal area 85 in the illustrated example is formed by a curved surface having a predetermined radius of curvature. The cross-sectional width (contact width Ws) of the seal area 85 when only the elastic force of the lip portion 39 acts thereon is preferably 0.1 mm or more and 0.5 mm or less.

[0087] For example, if the front annular seal 36 is a general oil seal (nitrile rubber, hardness 70), the radius of curvature of the seal portion 85 may be set to 0.4 mm or more and 5 mm or less. This makes it easy to set the preferred contact width Ws.

[0088] The sealing portion 85 may be a flat surface instead of a curved surface. For example, the corner of the tip of the lip portion 39 is chamfered to form a flat surface with a preferable contact width Ws, taking into account the contact angle. Since the lip portion 39 is elastically deformable, it can be made to come into surface contact with the sliding surface 41 with a predetermined contact width even if the contact angle is deviated.

[0089] The sealing state when air is supplied to the annular spaces 43, 48 will be described with reference to Fig. 6. A simplified diagram of the front seal structure as viewed from the axial direction is shown in the upper part of Fig. 6. The graph shown below shows an example of the contact width Wn over the entire circumferential area of ​​the front annular seal material 36, developed based on the position r0.

[0090] The air pressure Pi in the air supply passage is adjusted to a predetermined air pressure (Pi>P0) higher than the air pressure P0 outside the indexing device 1. As a result, as shown in the graph, at least a part of the seal portion 85 of the front annular seal material 36 is in surface contact with the outer circumferential surface (sliding surface 41) of the table 4 within the range of the contact width Ws described above, that is, as shown in FIG. 6(a), with a contact width Wn that is equal to or smaller than the contact width Ws.

[0091] Then, in the remaining part of the sealing area 85, as shown in (b) of Figure 6, the sealing area 85 is pushed up from the sliding surface (contact width Wn is 0), and air is blown out from between the sealing area 85 and the sliding surface 41, as shown by the arrow Ya.

[0092] 6 is an example of the contact state between the seal area 85 and the sliding surface 41. The size and distribution of the contact width Wn are not uniform and may change depending on the situation. The surface contact referred to here is a comprehensive one, and includes transitional line contact that occurs at the boundary between the area from which air is blowing and the area in surface contact, and dynamic temporary line contact.

[0093] In other words, it is sufficient that air blows out from a part of the entire circumference of the front annular seal 36 and the other parts are in substantial surface contact. It is also acceptable for the entire circumference of the front annular seal 36 to be in substantial surface contact and for air to blow out intermittently from some parts of the circumference.

[0094] Even if the seal portion 85 is in surface contact, the lip portion 39 is lifted by air pressure, so the contact area can be minimized. Therefore, the contact pressure is suppressed, and the rotational torque, frictional resistance, and wear can be reduced.

[0095] The relative circumferential positions of the seal portion 85 and the sliding contact surfaces 41, 46 change with the rotation of the table 4. The position from which the air is blown out also changes accordingly. Therefore, even if the air is blown out only partially, the air can be blown out efficiently over the entire circumference.

[0096] Since air is blown out from a part of the surface, it can be blown out with a strong force even with a small amount of air supply. Therefore, adhesion of powdery chips can be suppressed. When a depression is formed on the sliding surfaces 41, 46 due to wear, air is particularly likely to blow out from the depression, so the progress of wear can be effectively suppressed.

[0097] 5, since the sealing portion 85 is adjacent to the bending gap 82, the blown air is directed toward the bending gap 82. Therefore, it becomes difficult for powdery chips to enter the bending gap 82, and the intrusion of powdery chips can be suppressed. Note that it is preferable to set the sealing portion 85 so that air is always blown out from one of the circumferential directions.

[0098] It is at the seal portion 85 where contact pressure acts that a depression is formed on the sliding surfaces 41, 46 due to the adhesion of powder-like chips. However, since the seal portion 85 is in surface contact with the sliding surfaces 41, 46, even if a depression H is formed and the sliding surfaces 41, 46 are eroded as shown in Fig. 7, the seal portion 85 remains at the back with a predetermined width Wr. Therefore, airtightness can be ensured.

[0099] (Air flow rate test results) Figures 8 and 9 show test results regarding the setting of the air flow rate in the above-mentioned indexing device 1. Figure 8 shows the test results when the diameter of the table 4 is 160 mm, and Figure 9 shows the test results when the diameter of the table 4 is 320 mm.

[0100] The restriction is the amount of restriction of the first throttle valve 64 (diameter φ of the flow passage cross section: mm). The air pressure (kPa) is the air pressure in the front annular space 43. The air flow rate (L / min) is the amount of air supplied in the front air supply passage 60. The judgment was made comprehensively from the viewpoint of energy saving with respect to air consumption, sealing performance, wear resistance, low noise, etc.

[0101] The inventors have confirmed that if the air pressure is 5 kPa or more, the sealing performance of the seal portion 85 can be ensured. On the other hand, the throttle amount of 0.1 corresponds to the minimum value that can be adjusted by a commonly used throttle valve. Regardless of the size of the table 4, if the throttle amount is adjusted to 0.1, that is, by using a throttle valve, an air pressure of 5 kPa or more can be ensured.

[0102] Therefore, with a throttle valve, the air pressure and supply volume can be set cheaply and easily.

[0103] When the throttle amount is adjusted to a larger value, the air pressure and air flow rate increase. Accordingly, the contact pressure of the seal portion 85 decreases, and the contact width Wn decreases overall. Air is more likely to be blown out, and the amount of air consumption increases.

[0104] If the air supply rate exceeds 12 L / min, this is not preferable from the viewpoint of energy conservation. On the other hand, if the air supply rate is 12 L / min or less, it is possible to ensure that the air is appropriately blown out from the seal portion 85, and the amount of air consumed can be reduced. Therefore, it is possible to achieve energy conservation and noise reduction while suppressing the intrusion of powdery cutting chips.

[0105] The disclosed technology is not limited to the above-described embodiment, but also includes various other configurations.

[0106] For example, in the embodiment, a type in which the motor 7 is disposed in the box 6 has been exemplified, but the motor 7 may be disposed in the accommodation chamber 10a and may be a type that directly rotates the spindle 3 (so-called direct drive).

[0107] In the embodiment, the measures against the intrusion of powder-like chips have been specifically described for the front annular seal 36, but the same is true for the rear annular seal 37. Therefore, in the indexing device 1, measures against the intrusion of powder-like chips are taken for the front and rear seal structures. The annular seals 36 and 37 may be attached to the rotating side.

[0108] The main target of machining is brittle materials that generate powdery chips, but it is also effective for extremely soft metallic ductile materials (specific ductile materials) such as aluminum. Even such specific ductile materials can generate powdery chips during cutting depending on the machining conditions. [Explanation of symbols]

[0109] 1. Indexing device (rotating equipment) 2. Chassis 3 Spindle 4 Tables 5. Clamp 6 Box 7 Motor 10 Main body 10a Containment Room 11 Front cover 12 Rear lid part 13 Front opening 19 Bearings 33 Anterior slit 34 Posterior slit 36 Front annular seal 37 Rear annular seal 38 Base 39 Lip 40 Front step groove 41 Table outer surface (sliding surface) 43 Front annular space 46 Spindle outer surface (sliding surface) 48 Rear annular space 50 Front second annular seal 53 Rear second annular seal material 60 Front air supply passage 64 First throttle valve 65 Air supply pipe 67 Relay recess 70 Rear air supply passage 85 Seal area J Rotation axis W work

Claims

1. A rotating device for supporting an object to be processed during cutting, comprising: a housing having a cylindrical opening on a front side; a table rotatably disposed inside the opening via a narrow gap; an annular seal material that closes the gap; an air supply passage for supplying air at a predetermined pressure to an annular space present inside the annular seal; Equipped with The annular sealing material is An annular base; an elastically deformable lip portion extending from the base and having a predetermined sealing portion at a tip portion thereof; having the base is attached to one of the opening and the table such that the sealing portion is in contact with a sliding contact surface of the other of the opening and the table with a tip side of the lip portion facing outward from the narrow gap, a rotating device in which, when the air is not supplied to the annular space, the entire sealing portion is configured to be in surface contact with the sliding surface at a predetermined contact width, and when the air is supplied to the annular space, the air is configured to be blown out from the remainder of the sealing portion with at least a portion of the sealing portion in surface contact with the sliding surface within the range of the contact width.

2. The rotating device according to claim 1 , A rotating device, wherein the air pressure in the annular space is set to 5 kPa or more, and the air supply amount is set to 12 L / min or less.

3. The rotating device according to claim 2 , A rotating device, wherein a throttle valve is provided in the air supply passage, and the pressure and supply amount of the air are set by the amount of throttling of the throttle valve.

4. The rotating device according to claim 1 , A rotating device, wherein the sealing portion is a curved or flat surface formed by chamfering a corner of a tip portion of the lip portion.

5. In the rotating device according to any one of claims 1 to 4, Rotating equipment used in cutting processes that generates powder-like chips with no curled areas.

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