Shield tunneling machine

Abstract

To enable the improvement of the heat exhaust performance within a shield tunneling machine.SOLUTION: A girdering R between an interior chamber 7 and a rear chamber 9 of a shield tunneling machine 1 is provided with ventilation port parts V1 and V2 that connect the interior chamber 7 and the rear chamber 9. A blower F1 for sending air from the rear chamber 9 toward the interior chamber 7 is provided at the relatively lower ventilation port part V1, and a blower F2 for sending air from the interior chamber 7 toward the rear chamber 9 is provided at the relatively upper ventilation port part V2, so that the air in the interior chamber 7 can be efficiently cooled.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a shield tunneling machine, and more particularly to a cooling technique for a shield tunneling machine. [Background technology]

[0002] A shield tunneling machine is an excavation machine that excavates the ground by rotating the cutter head, which is attached to the tip in a freely rotatable manner, while pressing it against the excavation face (face), and then assembling segments on the inner wall of the excavation hole formed by the excavation.

[0003] Inside this shield machine, heat sources such as the cutter motor that drives the cutter head and the hydraulic jack that drives the shield machine are installed, so the inside of the shield machine is likely to become hot as it excavates. In particular, when using a shield machine to excavate ground consisting of gravel layers or clay or earthen layers, high torque is required, so the cutter motor tends to heat up easily.

[0004] Therefore, a cooling technology for a shield tunneling machine is described, for example, in Patent Document 1, which discloses a configuration in which a cooling means is installed on the trailing carriage of the shield tunneling machine to lower the temperature inside the shield tunneling machine using cooling water and cold air.

[0005] Furthermore, for example, Patent Document 2 discloses a configuration in which the evaporator section of a refrigerator is placed in a heat exchanger provided at one end of an air guide pipe that introduces outside air into a shield tunneling machine, and the refrigerant gas that has been heat exchanged in the heat exchanger is used to cool the mud water in the mud transport pipe of the shield tunneling machine. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 5-288370 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-129791 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when the shield tunneling machine is stopped and the segments are assembled, the cutter motor also stops, but when the cutter motor is stopped, the cooling fan attached to the cutter motor also stops, so the heat generated by the cutter motor cannot be fully dissipated and ends up accumulating inside the machine compartment where the cutter motor is installed.As a result, the shield tunneling machine must be kept stopped and wait until the cutter motor temperature drops naturally, which poses the problem of lengthening the construction cycle.

[0008] In addition, the temperature inside the shield tunneling machine rises due to heat from the cutter head, heat from other equipment, and frictional heat, which poses challenges in terms of the working environment.

[0009] The present invention has been made in light of the above-mentioned technical background, and aims to provide a technology that can improve the heat dissipation performance within a shield tunneling machine.

[0010] Another object of the present invention is to provide a technique for preventing the construction cycle of excavation tunnels using a shield machine from becoming longer.

[0011] Another object of the present invention is to provide a technique that can improve the working environment inside a shield tunneling machine. [Means for solving the problem]

[0012] In order to solve the above problems, the shield machine of the present invention as described in claim 1 is a shield machine that assembles segments on the inner wall surface of a borehole excavated by a cutter head rotatably mounted on the tip surface of the equipment body, and comprises a hollow outer shell portion that constitutes the outer shell of the equipment body, a partition plate that is mounted inside the outer shell portion facing the back surface of the cutter head, a chamber space that is mounted inside the outer shell portion between the cutter head and the partition plate, and a shield machine that is mounted inside the outer shell portion adjacent to the chamber space via the partition plate. The machine comprises an interior compartment, a cutter head driving means provided inside the interior compartment and driving the cutter head, a ring girder provided inside the outer shell portion opposite the back surface of the partition plate, a rear compartment provided inside the outer shell portion adjacent to the interior compartment via the ring girder, and an erector provided inside the rear compartment so as to overlap the central opening of the ring girder in a plan view and for assembling the segments, and the ring girder is provided with a plurality of vent portions connecting the interior compartment and the rear compartment.

[0013] The shield tunneling machine of the present invention described in claim 2 is characterized in that, in the invention described in claim 1 above, the ventilation port sections have one or more first ventilation port sections and one or more second ventilation port sections, and at least one of the first ventilation port sections is provided with a first ventilation means for blowing air from the rear compartment toward the interior compartment, and at least one of the second ventilation port sections is provided with a second ventilation means for blowing air from the interior compartment toward the rear compartment.

[0014] The shield tunneling machine of the present invention described in claim 3 is characterized in that, in the invention described in claim 2, the first vent port portion is provided below the second vent port portion.

[0015] The shield tunneling method of the present invention described in claim 4 is characterized in that, in the invention described in any one of claims 1 to 3 above, a cooling means is provided in the machine compartment that drives independently of the cutter head driving means and cools the cutter head driving means. [Effects of the Invention]

[0016] According to the present invention, it is possible to improve the heat dissipation performance within a shield tunneling machine.

[0017] Furthermore, according to the present invention, it is possible to prevent the construction cycle of excavation tunnels using a shield machine from becoming longer.

[0018] Furthermore, the present invention makes it possible to improve the working environment inside the shield machine. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a side view of a shield tunneling machine according to an embodiment of the present invention. [Figure 2] FIG. 2 is a rear view of the shield machine of FIG. 1 at the position of line II, viewed from the direction of the arrow. [Figure 3] 2 is a rear view of the shield machine of FIG. 1 at the position of line II-II, seen from the direction of the arrow. [Figure 4] FIG. 2 is an enlarged perspective view of a main part of the ring girder of the shield tunneling machine of FIG. 1. [Figure 5] FIG. 2 is a schematic diagram of a cooling mechanism for cooling the interior of the shield tunneling machine of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings for explaining the embodiment, the same components are generally designated by the same reference numerals, and repeated description thereof will be omitted.

[0021] Figure 1 is a side view of a shield tunneling machine of this embodiment, Figure 2 is a rear view of the shield tunneling machine in Figure 1, viewed from the direction of the arrow at the position on line II, Figure 3 is a rear view of the shield tunneling machine in Figure 1, viewed from the direction of the arrow at the position on line II-II, Figure 4 is an enlarged oblique view of the main parts of the ring girder of the shield tunneling machine in Figure 1, and Figure 5 is a schematic diagram of the cooling mechanism for cooling the interior compartment of the shield tunneling machine in Figure 1.

[0022] For the purpose of explanation, the interior of the shield machine 1 is shown as a see-through view in Figure 1. In this embodiment, the excavation direction of the shield machine 1 (the direction toward the tunnel face) is referred to as the forward direction, and the direction directly opposite to this forward direction (the direction toward the starting shaft) is referred to as the rearward direction.

[0023] As shown in Figure 1, the shield tunneling machine 1 of this embodiment is a mud-type shield tunneling machine that excavates the ground by pressing the cutter head 2 against the face and rotating it, and then pressurizes mud through a mud supply pipe 5 into a mud chamber (chamber) 4 located inside the equipment main body 3 behind the cutter head 2, and stabilizes the face by adjusting the mud pressure in the mud chamber 4 to a pressure that matches the earth pressure and groundwater pressure at the face, while discharging the mud stored in the mud chamber 4 to the outside of the excavation tunnel through a mud discharge pipe 6, forming an excavation tunnel in the ground and assembling segments SG on the inner wall surface of the excavation tunnel.

[0024] Although not particularly limited, the diameter of the shield tunneling machine 1 (ie, the diameter of the cutter head 2) is, for example, about 4030 mm, and the length of the shield tunneling machine 1 is, for example, about 7900 mm.

[0025] The cutter head 2 is an excavation member that is circular in front view and excavates the working face, and is supported on the front end surface of the equipment body 3 so as to be rotatable in both forward and reverse directions along the circumferential direction of the equipment body 3. The cutter head 2 is, for example, a face plate-type cutter head, and its front surface (the surface facing the working face) is fitted with a number of bits and scraper teeth (not shown) for crushing boulders and excavating the natural ground, as well as a through-hole (not shown) for taking the earth and sand excavated by the rotation of the cutter head 2 into the mud chamber 4.

[0026] In addition, a copy bit 2c is attached to the outer surface of the cutter head 2 to perform over-excavation when constructing a sharp curve and to control the attitude of the shield machine 1.

[0027] The device body 3 behind the cutter head 2 includes a front body section 3a, a rear body section 3b provided behind the front body section 3a, and a tail seal section 3c provided at the rear end of the rear body section 3b.

[0028] The skin plates (outer shell portions) M that form the outer shell of the equipment main body 3 are formed, for example, from cylindrical steel plates, and include a forward body plate M1 that forms the outer shell of the forward body section 3a, and an aft body plate M2 that forms the outer shell of the aft body section 3b. The forward body plate M1 and the aft body plate M2 are engaged with each other by inserting a spherical bearing portion on the forward end side of the aft body plate M2 into contact with the inner circumferential surface on the aft end side of the forward body plate M1.

[0029] Within the hollow interior of the forward plate M1 of the forward section 3a, a mud chamber 4 and an internal compartment 7 are formed, in that order from the cutterhead 2 toward the rear. The mud chamber 4 is a space that takes in earth and sand excavated by the rotation of the cutterhead 2 and mixes it with mud supplied through a mud pipe 5, and is located inside the forward plate M1 between the cutterhead 2 and a bulkhead plate 8. The internal compartment 7 is a space that houses various devices of the shield tunneling machine 1 and is located adjacent to the mud chamber 4 via the bulkhead plate 8. The bulkhead plate 8 is a steel plate that divides the hollow interior of the forward plate M1 into a face side and an internal compartment, and is located within the hollow interior of the forward plate M1, set back inward from the front end face of the forward plate M1, facing the back surface of the cutterhead 2.

[0030] A rear chamber 9 is formed in the hollow interior of the rear body plate M2 of the rear body section 3b. The rear chamber 9 is a space where ring-shaped segments SG are mainly assembled on the inner circumferential surface of the excavation hole, and is provided adjacent to the cabin 7 via a ring girder R.

[0031] The tail seal portion 3c is a water-stopping mechanism that prevents groundwater, backfill material, etc. from flowing into the inside of the equipment main body 3, and is installed in a ring shape along the circumferential direction of the rear body plate M2 while being joined to the inner surface of the rear end portion of the rear body plate M2.

[0032] The rear end of the tail brush 3cb that constitutes this tail seal portion 3c is in close contact with the outer peripheral surface of the segment SG, and water-stopping performance is maintained by constantly supplying filler (tail grease) to the tail brush 3cb itself and the contact area with the segment SG.

[0033] Here, an example is shown in which the tail brushes 3cb are installed in four rows at predetermined intervals along the shield excavation direction, but the number of rows of the tail brushes 3cb is not limited to this and can be changed in various ways, for example, it may be three rows or less.

[0034] Inside such equipment body 3 (hollow interior of skin plate M), a mud transport pipe 5, a mud discharge pipe 6, multiple cutter motors (cutter head driving means) 10, multiple bending jacks 11a, multiple shield jacks 11b, a ring girder R, an erector E, etc. are installed.

[0035] The mud pipe 5 is a steel pipe that supplies mud into the mud chamber 4. The front end (mud discharge port) of the mud pipe 5 passes through the upper inside front part of the partition plate 8 and reaches the mud chamber 4. As a result, the mud pumped through the mud pipe 5 is supplied into the mud chamber 4 from the upper inside front part of the shield machine 1.

[0036] The rear end of the mud transport pipe 5 extends towards the mouth of the borehole and is mechanically connected to a mud layer (not shown) outside the borehole via a number of mud transport pumps (not shown) arranged at regular intervals along the way. The mud tank is mechanically connected to a mud treatment device (not shown) outside the borehole.

[0037] The mud discharge pipe 6 is a steel pipe that discharges the discharged mud water (a mixture of excavated earth and mud water) from the mud chamber 4 to the outside of the excavation hole. The front end (mud intake port) of the mud discharge pipe 6 passes through the lower front interior part of the partition plate 8 and reaches the mud chamber 4. As a result, the discharged mud water from the mud chamber 4 is discharged from the lower front interior part of the shield tunneling machine 1.

[0038] The rear end of the mud discharge pipe 6 extends towards the mouth of the excavation hole and is mechanically connected to the mud treatment device outside the excavation hole via a number of mud discharge pumps (not shown) arranged at regular intervals along the way. The mud discharged from the mud chamber 4 is sent through the mud discharge pipe 6 to a mud treatment device outside the excavation hole, where it is separated into earth and mud and its specific gravity and viscosity are adjusted before being sent to a mud tank and then sent back to the mud chamber 4 through the mud delivery pipe 5.

[0039] As shown in FIGS. 1 and 2, the cutter motor 10 is a driving body that rotates the cutter head 2 in both forward and reverse directions, and a plurality of cutter heads 10 are installed in the machine interior 7.

[0040] A cooling fan CF is installed behind each cutter motor 10. In Fig. 1 and Fig. 2, the cooling fan CF is hatched to make the drawings easier to see.

[0041] The cooling fans CF are cooling means for air-cooling the cutter motors 10, and are arranged so as to overlap each cutter motor 10 in plan view, as shown in Fig. 2. This improves the cooling capacity of the cooling fans CF for the cutter motors 10. However, the cooling fans CF may be arranged in other positions as long as they can cool the cutter motors 10.

[0042] Furthermore, the cooling fan CF can be driven independently of the cutter motor 10, and is designed to forcibly cool the cutter motor 10 24 hours a day. This allows the cutter motor 10 to be cooled by the cooling fan CF even while the shield machine 1 is stopped from excavating (i.e., while the cutter motor 10 is also stopped from driving). Note that the standard capacity of each cooling fan CF is the same.

[0043] As shown in Figure 1, the bending jack 11a is a device that connects the forward body section 3a and the rear body section 3b and corrects the excavation direction of the shield tunneling machine 1, and multiple bending jacks 11a are installed inside the machine compartment 7 along the inner circumference of the forward body plate M1.

[0044] As shown in Figures 1 to 3, the shield jack 11b is an equipment that receives a reaction force from the segment SG at the rear of the equipment main body 3 and pushes the segment SG rearward to advance the shield tunneling machine 1, and multiple shield jacks 11b are fixed along the inner circumference of the rear body plate M2.

[0045] As shown in Figure 1, each shield jack 11b is fixed inside the rear chamber 9, but is installed with the extrusion portion at the rear end of the shield jack 11b protruding into the aircraft cabin 7 through a through hole drilled in the ring girder R.

[0046] The ring girder R is a steel structural part that holds the earth pressure acting on the skin plate M, prevents deformation of the skin plate M, and connects the forward and aft sections 3a and 3b, and is formed in a ring shape in plan view along the inner periphery of the aft plate M2, as shown in Figures 2 and 3. The outer periphery of the ring girder R is joined to the inner periphery of the aft plate M2.

[0047] The ring girder R is formed in a ring shape when viewed in a plane, but since the erector E (including driving equipment), mud transport pipe 5, mud discharge pipe 6, etc. are installed so as to block the central opening of the ring girder R, the interior room 7 is in a state where it is separated from the rear room 9, and the interior room 7 is prone to trapping heat generated by the cutter motor 10, shield jack 11b, etc., and the temperature is likely to rise.

[0048] Therefore, in this embodiment, the ring girder R is provided with ventilation openings V1 and V2 that communicate between the interior compartment 7 and the rear compartment 9. One each of the ventilation openings V1 and V2 is provided, and is configured by fitting a cylindrical steel pipe P into a through-hole H that penetrates between the front and rear surfaces of the ring girder R, as shown in FIG.

[0049] 5, a blower (first blowing means) F1 is installed in the vent V1 to send air from the rear compartment 9 into the interior of the aircraft cabin 7. Therefore, the vent V1 functions as an air intake port that supplies air from the rear compartment 9 to the interior of the aircraft cabin 7.

[0050] Meanwhile, a blower (second blowing means) F2 that sends air from the interior of the aircraft cabin 7 into the rear compartment 9 is installed in the ventilation port V2. Therefore, the ventilation port V2 functions as an exhaust port that exhausts air from the interior of the aircraft cabin 7 to the rear compartment 9.

[0051] In this embodiment, the fans F1 and F2 have the same standard capacity, but as a modified example, the standard capacities of the fans F1 and F2 may be different. Also, to make the drawing easier to understand, the cooling fan CF described above is not shown in Figure 5.

[0052] 2 and 3, the vent V1 is disposed, for example, below the center in the height direction of the skin plate M in a plan view. This allows relatively low-temperature air in the rear compartment 9 to be supplied to the aircraft cabin 7 through the lower vent V1.

[0053] On the other hand, the vent V2 is disposed, for example, above the center in the height direction of the skin plate M in a plan view. Therefore, the air that is heated and rises in the aircraft cabin 7 can be discharged to the rear compartment 9 through the upper vent V2.

[0054] For this reason, in this embodiment, the air inside the machine chamber 7 of the shield machine 1 can be circulated efficiently, thereby improving the heat dissipation performance inside the machine chamber 7. Therefore, the temperature inside the machine chamber 7 can be lowered efficiently.

[0055] In this embodiment, the vents V1 and V2 are arranged at opposing positions on the circumferentially opposite sides of the interior 7. This allows air to circulate over a wide area within the interior 7, improving the heat dissipation performance within the interior 7. This allows the temperature within the interior 7 to be lowered efficiently.

[0056] Furthermore, like the cooling fan CF, the fans F1 and F2 can be driven independently of the cutter motor 10. Therefore, whether the shield machine 1 is excavating or stopped (i.e., whether the cutter motor 10, etc. is operating or stopped), the fans F1 and F2 can be driven to draw in and exhaust air from the interior chamber 7 through the vents V1 and V2, thereby lowering the temperature inside the interior chamber 7.

[0057] In other words, in this embodiment, when the shield tunneling machine 1 stops excavating, the cutter motor 10 itself can be cooled by the cooling fan CF as described above, and the temperature inside the machine compartment 7 can also be lowered by the fans F1 and F2, so that heat sources such as the cutter motor 10 and shield jack 11b can be sufficiently cooled.

[0058] This reduces the waiting time for cooling the cutter motor 10, shield jack 11b, etc., and prevents a longer excavation cycle using the shield machine 1. Furthermore, the temperature inside the machine compartment 7 of the shield machine 1 can be lowered, improving the working environment inside the machine compartment 7.

[0059] In the above example, the planar shape of the ventilation openings V1 and V2 is shown to be circular, but this is not limited to this and various modifications are possible, for example, it may be an oval shape or a square shape.

[0060] Furthermore, although the case where one vent hole portion V1, one vent hole portion V2 is provided on the ring girder R has been described, the present invention is not limited to this, and for example, a plurality of vent holes V1, V2 may be provided on the ring girder R. In this case, a blower F1 may be provided in at least one of the plurality of vent holes V1, and a blower F2 may be provided in at least one of the plurality of vent holes V2.

[0061] Furthermore, when a plurality of ventilation holes V1 and V2 are provided, the shapes and sizes (diameters and side lengths) of the plurality of ventilation holes V1 in a plan view may be the same or different. Similarly, the shapes and sizes (diameters and side lengths) of the plurality of ventilation holes V2 in a plan view may be the same or different. Furthermore, the shapes and sizes (diameters and side lengths) of the ventilation holes V1 and V2 in a plan view may be different.

[0062] In addition, when a plurality of vents V1 and V2 are provided, the number of vents V1 and the number of vents V2 may be the same or different. Furthermore, the above-described variations in the number and shape of vents V1 and V2 may be combined.

[0063] Furthermore, when there are a plurality of vent openings V1 and V2, the number of fans F1 and F2 may be different.

[0064] The erector E is a device that assembles ring-shaped segments SG on the inner surface of the excavation hole within the rear chamber 9, and is equipped with a segment gripping unit Eh, an axial moving unit Ex, a radial moving unit Ey, a support Es, an erector ring unit Er, and a ring drive motor Em.

[0065] The segment gripping unit Eh is an erector drive mechanism for gripping each individual segment SG, and is installed in the rear chamber 9 in a state where it can move freely along the slide shaft unit Exs of the axial movement unit Ex.

[0066] The axial moving unit Ex is an erector drive mechanism that moves the segment gripping unit Eh along the slide shaft unit Exs. The slide shaft unit Exs is mechanically connected to the vicinity of the end of the drive rod unit Eyr of the radial moving unit Ey.

[0067] The radial moving unit Ey is an erector drive mechanism that moves the segment gripping unit Eh in the radial direction of the rear body plate M2 (in the direction outward from the central axis of the shield excavator 1 and in the direction from the outside of the shield excavator 1 toward the central axis). The radial moving unit Ey is mechanically connected to the erector ring unit Er via the support Es.

[0068] The erector ring unit Er is an erector drive mechanism unit for rotating the segments SG held by the segment holding units Eh along the inner periphery of the rear body plate M2, and is installed so as to be able to rotate freely in both forward and reverse directions along the inner periphery of the rear body plate M2. The erector ring unit Er is formed in a ring shape in a plan view, and is arranged so as to overlap the central opening of the ring girder R in a plan view.

[0069] The ring drive motor Em is a drive source for rotating the erector ring unit Er and is configured, for example, by a hydraulic motor. When the ring drive motor Em rotates the erector ring unit Er along the inner periphery of the rear plate M2, the support body Es also rotates along the inner periphery of the rear plate M2 accordingly, and therefore the segment gripping unit Eh mechanically connected to the support body Es also rotates along the inner periphery of the rear plate M2.

[0070] The invention made by the inventor has been specifically described above based on the embodiments, but the embodiments disclosed in this specification are illustrative in all respects and are not limited to the disclosed technology. In other words, the technical scope of the present invention should not be interpreted restrictively based on the description of the above embodiments, but should be interpreted solely in accordance with the claims, and includes technologies equivalent to the technologies described in the claims and all modifications that do not deviate from the gist of the claims.

[0071] In the above embodiment, the cutter motor 10 is cooled by the cooling fan CF, but this is not limitative, and the cutter motor 10 may be cooled by other cooling means, such as water cooling. [Industrial Applicability]

[0072] In the above explanation, the present invention is applied to a slurry shield machine, but the present invention can also be applied to an earth pressure shield machine. [Explanation of symbols]

[0073] 1. Shield tunneling machine 2 cutter heads 2c Copy Cutter 3. Device body 3a Front trunk 3b Back torso 3c Tail seal part 3cb tail brush 4 Mud room (chamber room) 5 Sludge pipe 6 Sludge drainage pipe 7 Cabin 8 Bulkhead plate 9 Rear compartment 10 Cutter motor (cutter head drive means) 11a Folding jack 11b Shield Jack M Skin Plate M1 front fuselage plate M2 rear fuselage plate R Ring Girder V1 Vent (first vent) V2 Vent (Second Vent) H through hole P-pipe F1 blower (first blowing means) F2 blower (second blowing means) CF cooling fan (cooling means) E Erector Eh Segment gripping part Ex axial movement part Exs slide shaft part Ey Radial moving part Eyr drive rod Es erector support Er Erectoring Department Em ring drive motor SG Segment

Claims

1. A shield machine that assembles segments onto the inner wall surface of an excavated hole excavated by a cutter head rotatably mounted on the tip surface of the equipment body, a hollow outer shell portion that constitutes an outer shell of the device body; a partition plate provided inside the outer shell portion so as to face the rear surface of the cutter head; a chamber provided inside the outer shell between the cutter head and the partition plate; an internal compartment adjacent to the chamber via the partition wall inside the outer shell; a cutter head driving means provided inside the interior of the machine compartment and configured to drive the cutter head; A ring girder provided inside the outer shell portion so as to face the back surface of the bulkhead plate; A rear compartment provided adjacent to the cabin via the ring girder inside the outer shell portion; An erector that is provided inside the rear chamber so as to overlap the central opening of the ring girder in a plan view and assembles the segments; Equipped with A shield tunneling machine characterized in that the ring girder is provided with a plurality of ventilation openings that connect the interior compartment and the rear compartment.

2. the vent portion includes one or more first vent portions and one or more second vent portions, A shield machine as described in claim 1, characterized in that at least one of the first ventilation port sections is provided with a first ventilation means for blowing air from the rear compartment toward the interior compartment, and at least one of the second ventilation port sections is provided with a second ventilation means for blowing air from the interior compartment toward the rear compartment.

3. 3. The shield machine according to claim 2, wherein the first vent opening is provided below the second vent opening.

4. A shield tunneling machine as described in any one of claims 1 to 3, characterized in that a cooling means is provided in the machine chamber that drives independently of the cutter head driving means and cools the cutter head driving means.

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