Undercutter Device

Abstract

To suppress a chain belt from becoming loose even when the chain belt stops or when the chain belt suddenly stops due to excessive load.SOLUTION: An under cutter device includes a chain belt 11 that is provided with multiple drilling blades 11a, an under cutter drive part 12 that rotates the chain belt 11, a driven head 13, and a tension adjustment part 15; the tension adjustment part 15 has a cylinder part 15a that extends and contracts a piston rod 15b, a connecting rod 15f that is provided at the tip of the piston rod 15b and to which the driven head 13 is slidably connected, a coil spring 15i that is provided between the piston rod 15b and the driven head 13 and constantly presses the driven head 13 away from the under cutter drive part 12, and a resin-made front cushioning member 15j between the coil spring 15i and the driven head 13.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an undercutter device equipped with a tension adjustment unit (tensioning device) that adjusts the tension applied to a chain belt provided with a plurality of excavating blades. [Background technology]

[0002] Conventionally, chain belts (also called cutter chains) equipped with cutters (also called scrapers) of undercutter devices (see, for example, Patent Documents 1 to 3) that excavate the trackbed have been equipped with tension adjustment units (tensioning devices) that apply appropriate tension to the chain belts.

[0003] Such undercutter devices are machines that operate with the entire device inserted into the roadbed (crushed stone) under the sleepers, making it difficult to easily adjust them on the surface of the machine, as is the case with adjusting the tension of a bicycle chain or belt conveyor.

[0004] In addition, the height (thickness) of the device can only be secured in the limited space (150 to 250 mm) between the top surface of the roadbed and the bottom surface of the sleeper, so the current method of tension adjustment is to use a cylinder and coil spring. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5869487 [Patent Document 2] Patent No. 6817640 [Patent Document 3] Utility Model Registration No. 3225463 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in such an undercutter device, when the chain belt stops or when an excessive load occurs and it suddenly stops, the inertial force of the chain belt compresses the coil spring and causes a large displacement, which may cause the chain belt to temporarily loosen.The chain belt also loosens over time.

[0007] This causes deformation such as bending of the chain belt, which causes impacts on the components that make up the undercutter device and accelerates wear of the chain belt, ultimately increasing the failure rate of the entire undercutter device and shortening its lifespan.

[0008] Furthermore, if an attempt is made to prevent this, the coil spring will become larger, which may make it impossible to insert the coil spring into an existing tension applying mechanism.

[0009] Therefore, the present invention has been made with an eye on such problems, and aims to provide a tension applying device for an undercutter that makes it difficult for the chain belt to slacken even when the chain belt stops or when an excessive load is placed on the chain belt causing a sudden stop, thereby reducing the failure rate of the entire undercutter device and extending its lifespan. [Means for solving the problem]

[0010] In order to solve the above problem, the undercutter device of the present invention comprises: a chain belt having a plurality of continuous excavation blades for excavating the track bed; an undercutter drive unit that rotates the chain belt; a driven head that is provided opposite the undercutter drive unit and has a driven gear around which the chain belt is wound and that changes the direction of the chain belt; and a cutter body that has a tension adjustment unit that adjusts the tension of the chain belt by pushing the driven head away from the undercutter drive unit, wherein the tension adjustment unit comprises a cylinder unit that extends and retracts a piston rod; a connecting rod that is provided at the tip of the piston rod and to which the driven head is slidably connected; a coil spring that is provided between the piston rod and the driven head and that constantly presses the driven head away from the undercutter drive unit; and a front cushioning material that is provided between the coil spring and the driven head and that absorbs vibrations transmitted from the driven head. The undercutter device according to the present invention is also characterized in that the connecting rod is fixed to the piston rod via a rear holder having a larger diameter than the connecting rod, the coil spring is provided between a front holder having a larger diameter than the connecting rod and slidably provided on the connecting rod, and the rear holder, and the front buffer material is provided slidably relative to the connecting rod, with the connecting rod passing through between the front holder and the driven head. In addition, the undercutter device of the present invention is characterized in that a back plate made of a metal steel plate is provided between the front buffer material and the driven head, and the cross-sectional shapes of the front buffer material, the front holder, and the back plate are formed so that the lower part is wider than the upper part. In addition, in the undercutter device according to the present invention, the freon to The connecting rod passes through the holder and connects the front end of the rear holder to the rear end of the holder. toA cylindrical guide sleeve is provided that extends toward a rear guide provided on the holder side and is slidably attached to the connecting rod together with the front holder, while the connecting rod passes between the guide sleeve and the rear guide and is slidably attached to the connecting rod, and a rear buffer material is provided that abuts against both the guide sleeve and the rear guide to absorb vibrations or impacts when the gap between the front holder and the rear holder narrows. [Effects of the Invention]

[0011] In the undercutter device according to the present invention, the tension adjustment section of the chain belt not only has a coil spring that constantly pushes the driven head away from the undercutter drive section, but also has a front buffer material between the coil spring and the driven head. Therefore, even when the chain belt stops or if an excessive load is placed on the chain belt causing it to suddenly stop, the vibrations and impacts from the driven head around which the chain belt is looped are absorbed by the front buffer material and coil spring, making it less likely for the chain belt to become loose, reducing the failure rate of the entire undercutter device, extending its lifespan, and improving work efficiency. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a perspective view of an undercutter device according to an embodiment of the present invention; [Figure 2] 1 is a plan view of an undercutter device according to an embodiment of the present invention. FIG. [Figure 3] 1 is a perspective view of a driven head unit and a tension adjustment unit that constitute an undercutter device according to an embodiment of the present invention. FIG. [Figure 4] 2 is an enlarged plan view of a tension adjustment section and other components constituting the undercutter device according to the embodiment of the present invention. FIG. [Figure 5] 5(a) and (b) are cross-sectional views taken along line AA in FIG. 4 and line BB in FIG. 5(a), respectively. [Figure 6] (a) and (b) are cross-sectional views showing the state of the tension adjustment unit, etc. before the chain belt is attached in the undercutter device of the embodiment, and cross-sectional views showing the state of the tension adjustment unit, etc. at the start of excavation work after the chain belt is attached, respectively. [Figure 7] (a) and (b) are cross-sectional views showing the state of the tension adjustment unit, etc., in an embodiment of the undercutter device after the chain belt is attached and excavation work is performed, in which the chain belt has loosened due to aging, and (b) are cross-sectional views showing the state of the tension adjustment unit, etc., after the loosened chain belt has been reset to the cylinder unit. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the undercutter device 1 according to the present invention will be described in detail with reference to the accompanying drawings. Note that the undercutter device 1 of the embodiment described below is merely an example of the present invention, and the present invention is not limited to the following embodiment, and can be modified as appropriate within the scope of the technical concept of the present invention.

[0014] <Configuration of the undercutter device 1 according to the embodiment> As shown in Figures 1 to 4, the undercutter device 1 of this embodiment is configured with a chain belt 11 on which multiple excavation blades 11a are provided at predetermined intervals, an undercutter drive unit 12, a driven head 13, a cutter main body 14, a tension adjustment unit 15, etc.

[0015] In FIG. 1, reference numeral 2 denotes a coupler section to which an attachment connector at the tip of a working arm such as a backhoe (not shown) is connected, and reference numeral 3 denotes a rotary drive section that is provided in the coupler section 2 and to which a hydraulic pipe (hydraulic tube) from the backhoe is connected, and which incorporates a drive gear (not shown) that rotates by the hydraulic pressure.

[0016] The coupler section 2 comprises a coupler main body 2a incorporating a driven gear (not shown) that rotates the undercutter device 1 using hydraulic pressure from the backhoe via the rotary drive section 3, and a pair of pin connecting plates 2c, 2c provided at a predetermined distance on the upper surface of the coupler main body 2a, and the pair of pin connecting plates 2c, 2c are provided with a pin 2d for a large backhoe, a pin 2e for a small backhoe, and a common pin 2f.

[0017] On the underside of the coupler body 2a, there is provided a rotating disk 2g that rotates by a driven gear (not shown) built into the coupler body 2a, and a pair of cutter connecting plates 2h, 2h that extend downward from both sides of the rotating disk 2g and are connected to the undercutter device 1 of the embodiment.

[0018] (Chain Belt 11) The chain belt 11 is configured with a plurality of excavation blades (also called cutters or scrapers) 11a and scraping plates 11b provided at predetermined intervals on the outside, and is stretched between the drive gear (not shown) of the undercutter drive unit 12 and the driven gear (not shown) of the driven head 13, and rotates when the drive gear (not shown) of the undercutter drive unit 12 on the base end (rear end) side rotates due to hydraulic pressure or electric current supplied from a backhoe (not shown), causing the excavation blades (also called cutters or scrapers) 11a to excavate the track bed (ballast), and the scraping plates 11b, etc. to scrape out the track bed (ballast).

[0019] Here, the chain belt 11 loosens over time, and when it does loosen, the tension adjusting unit 15 is configured to eliminate the looseness.

[0020] (Undercutter drive unit 12) The undercutter drive unit 12 is provided at the base end of the device 1, i.e., the rear end side of the cutter main body unit 14, and is configured to rotate a drive gear (not shown) using hydraulic pressure or electric current supplied from a backhoe (not shown), rotate a chain belt 11 wrapped around the drive gear (not shown), excavate the ballast with an excavation blade (also called a cutter or scraper) 11a, and scrape out the ballast with an excavation plate 11b, etc.

[0021] (Driven Head 13) The driven head 13 is arranged at the tip of the device 1, that is, on the tip side of the cutter main body 14, opposite the undercutter drive unit 12, and is configured to change the direction of the chain belt 11.It is equipped with a driven head slide frame 13a, an upper head plate 13b arranged to cover the upper side of the tip of the driven head slide frame 13a, a lower head plate 13c arranged to cover the lower side of the tip of the driven head slide frame 13a, and a driven gear 13d which is rotatably arranged at the tip of the driven head slide frame 13a, around which the chain belt 11 is looped, and which rotates to change the direction of the chain belt 11, and is configured to change the direction of the chain belt 11.

[0022] The driven head slide frame 13a is formed in the shape of a rectangular box, and has a driven gear 13d rotatably attached to its tip, while a rear end plate 13a1 is provided at its rear end, with a connecting hole 13a11 formed therein through which the tip of a connecting rod 15f of the tension adjustment unit 15 passes. The driven head slide frame 13a and the connecting rod 15f are not fixed to each other, and the driven head slide frame 13a is provided so as to be able to slide relative to the connecting rod 15f. However, the tip of the connecting rod 15f is inserted a predetermined length into the driven head slide frame 13a through the connecting hole 13a11 of the rear end plate 13a1, and when the device 1 is in use, the chain belt 11 is wound around the driven head slide frame 13a, applying tension to the driven head slide frame 13a, so there is no problem even if the driven head slide frame 13a and the connecting rod 15f are not fixed to each other.

[0023] A gap cover plate 13b1 is provided on the rear end side of the head upper plate 13b to cover the gap that occurs between the rear end of the head upper plate 13b and the tip of the cutter body upper plate 14a of the cutter body 14 when the driven head 13 is pressed and moved by the tension adjustment part 15 of the cutter body 14.

[0024] (cutter body 14) The cutter main body 14 comprises a cutter main body frame (not shown) provided between the undercutter drive unit 12 and the driven head 13, and an upper cutter main body plate 14a and a lower cutter main body plate 14b arranged at a regular interval so as to cover the top and bottom of the cutter main body frame (not shown), and a tension adjustment unit 15 for adjusting the tension of the chain belt 11 is built in between the cutter main body frame (not shown) and the driven head slide frame 13a.

[0025] (Tension adjustment part 15) The tension adjusting unit 15 is built into the cutter body 14 and connected to a cutter body frame (not shown) of the cutter body 14 via a cylinder connecting portion 15a1. The tension adjusting unit 15 includes a cylinder portion 15a that extends a piston rod 15b by injecting grease from a grease nipple 15a2 provided on the cylinder connecting portion 15a1, a guide bush holder 15c that is fixed to a piston rod connecting portion 15b1 at the tip of the piston rod 15b with a fixing split pin 15c1 and that holds guide bushes 15c1 and 15c2, a rear holder 15d that is fixed to the guide bush holder 15c with a screw 15d1, and a rear holder 15d. a rear guide 15e fixed to the rear holder 15d with a screw 15d1; a connecting rod 15f extending in the axial direction of the piston rod 15b, with a large-diameter connecting portion 15f1 fitted into a ring-shaped annular recess formed between the rear holder 15d and the rear guide 15e; a guide sleeve 15g provided on the connecting rod 15f via an oiles bushing 15g1 so as to be slidable in the longitudinal direction of the connecting rod 15f; and a front holder 15h fixed to the large-diameter annular portion 15g2 of the guide sleeve 15g with a screw 15g3, and a coil spring 15i provided between the front holder 15h and the rear holder 15d.

[0026] In the tension adjustment section 15 of this embodiment, a front resin cushioning material 15j made of elastic resin (including rubber) is provided between the front holder 15h and the rear end plate 13a1 at the rear end of the driven head slide frame 13a.

[0027] Here, as shown in Figure 4, etc., the width W2 of the front resin buffer material 15j is made larger than the width W1 of the driven head slide frame 13a (W2>W1), so that a back plate 15k such as a metal plate having the same cross-sectional shape as the front resin buffer material 15j is provided between the rear end plate 13a1 at the rear end of the driven head slide frame 13a and the front resin buffer material 15j.

[0028] As shown in FIG. 5 and other figures, the height H1 of the front resin buffer material 15j is the same as the height H2 of the driven head slide frame 13a, but is larger than the outer diameter R1 (see FIG. 4) of the coil spring 15i.

[0029] Furthermore, in the tension adjusting section 15 of this embodiment, a cylindrical rear resin buffer material 15m is provided inside the coil spring 15i between the guide sleeve 15g and the rear guide 15e, and the connecting rod 15f passes through the annular shape.

[0030] The rear resin cushioning material 15m is formed in a ring shape from a material such as elastic resin (including rubber) similar to the front resin cushioning material 15j.

[0031] Therefore, if the inner diameter of the coil spring 15i is R2 (see Figure 5), and the outer diameter of the rear resin buffer material 15m is R3 (see Figure 4), then R3 <R2<R1

[0032] Furthermore, as shown in Figures 6(b) and 7(b) described below, even when the rear resin buffer material 15m abuts against the rear end of the guide sleeve 15g and the front end of the rear guide 15e and is sandwiched between the guide sleeve 15g and the rear guide 15e, the coil spring 15i does not completely contract but expands and contracts, allowing it to absorb vibrations, shocks, etc.

[0033] The rear resin buffer material 15m may be made of the same material as the front resin buffer material 15j, but it is not only smaller in width and height than the front resin buffer material 15j, but also shorter in length in the longitudinal (axial) direction of the connecting rod 15f, and is therefore a supplementary (backup) buffer material for the front resin buffer material 15j. Since it is necessary to avoid as much as possible the transmission of vibrations and shocks generated in the driven head 13 to the cylinder portion 15a and cutter main body portion 14, it is of course also possible to use a different material, such as a material that is harder than the front resin buffer material 15j.

[0034] <Operation of the undercutter device 1 of the embodiment> ​Next, the operation of the undercutter device 1 of the embodiment configured as above will be described with reference to the drawings.

[0035] (Before installing Chain Belt 11) Before the chain belt 11 is attached, the coil spring 15i and other components provided between the rear holder 15d and the front holder 15h are not under load and are in a load-free state, so the coil spring 15i is stretched, widening the gap between the rear holder 15d and the front holder 15h as shown in Figure 6(a), and a gap G1 is generated between the guide sleeve 15g and the rear resin buffer material 15m.

[0036] The length of the piston rod 15b projecting from the cylinder portion 15a before the chain belt 11 is attached is set to L0 as shown in FIG. 6(a).

[0037] (At the start of excavation work with chain belt 11 attached) When attaching the chain belt 11 and starting excavation work using the undercutter device 1 of this embodiment, the chain belt 11 is looped around the undercutter drive unit 12, driven head 13, cutter main body unit 14, etc., as shown in Figure 1, etc.

[0038] Then, in order to apply tension to the chain belt 11, the worker extends the piston rod 15b from the cylinder portion 15a in the α direction as shown in Figure 6(b) to protrude it by the protruding length L1 (>L0), so that the tip of the rear resin buffer material 15m abuts against the rear end of the guide sleeve 15g, and the rear resin buffer material 15m is sandwiched between the guide sleeve 15g and the rear guide 15e.

[0039] 6(b), the piston rod 15b extends from the cylinder portion 15a by "L1-L0." Also, even when the rear resin shock absorber 15m is sandwiched between the guide sleeve 15g and the rear guide 15e as shown in FIG. 5(b), the coil spring 15i is not completely contracted and is able to expand and contract to absorb vibrations, shocks, and the like.

[0040] Therefore, in this state, when the undercutter device 1 is used to rotate the chain belt 11 and perform excavation work on the track bed using the excavation blade 11a and scraping plate 11b provided on the outside of the chain belt 11, the vibrations and impacts are transmitted to the driven head 13 via the chain belt 11, and are also transmitted to the coil spring 15i, etc.

[0041] However, in the undercutter device 1 of this embodiment, a front resin buffer material 15j is provided between the driven head 13 and the driven head slide frame 13a via a front holder 15h, so that small vibrations and impacts from the driven head 13 are absorbed by the front resin buffer material 15j, and the vibrations and impacts transmitted from the driven head 13 to the coil spring 15i are reduced.

[0042] As a result, compared to when the driven head slide frame 13a of the driven head 13 is pressed directly by the coil spring 15i without providing the front resin buffer material 15j, the reaction force that the chain belt 11 receives from the coil spring 15i due to its own vibration, impact, etc. is reduced, making the chain belt 11 less likely to loosen and improving the workability of the trackbed excavation work.

[0043] Furthermore, in this state, when the undercutter device 1 is used to rotate the chain belt 11 and perform excavation work on the trackbed using the excavation blade 11a on the outside of the chain belt 11, the resulting vibrations and impacts are absorbed by the front resin buffer material 15j via the chain belt 11 and the driven head 13, but the vibrations and impacts acting in the longitudinal (axial) direction of the connecting rod 15f may not be fully absorbed by the front resin buffer material 15j and are transmitted to the coil spring 15i and guide sleeve 15g via the front resin buffer material 15j and front holder 15h.

[0044] However, in the undercutter device 1 of this embodiment, in addition to the front resin cushioning material 15j, a rear resin cushioning material 15m is provided between the guide sleeve 15g and the rear guide 15e, and the rear resin cushioning material 15m is sandwiched between the guide sleeve 15g and the rear guide 15e and is in contact with them, and even in this contact state, the coil spring 15i is still able to contract as shown in Figure 5(b). Therefore, vibrations and impacts acting in the longitudinal (axial) direction of the connecting rod 15f that cannot be fully absorbed by the front resin cushioning material 15j are absorbed by the rear resin cushioning material 15m and the coil spring 15i, and the vibrations and impacts transmitted from the driven head 13 to the cylinder portion 15a and the cutter main body portion 14 are further reduced.

[0045] As a result, compared to the case where only the coil spring 15i is provided between the front holder 15h and the rear holder 15d without providing the rear resin buffer material 15m, vibrations and shocks acting in the longitudinal (axial) direction of the connecting rod 15f that cannot be fully absorbed by the front resin buffer material 15j are absorbed not only by the coil spring 15i but also by the rear resin buffer material 15m, so the chain belt 11 is less likely to loosen to the extent that the rear resin buffer material 15m absorbs the vibrations and shocks, and the frequency (number of times) of the resetting work at the cylinder portion 15a, which will be described later, is reduced, thereby improving the workability of the trackbed excavation work.

[0046] (After drilling work with the chain belt 11 attached, if the chain belt 11 becomes loose due to aging) As shown in Figure 6(b), when the chain belt 11 is attached and excavation work is performed using the undercutter device 1 of this embodiment, the chain belt 11 gradually loosens or becomes slack due to vibrations and impacts during the excavation work.

[0047] Then, as shown in Figure 7(a), due to the elastic force of the coil spring 15i pressing the front holder 15h slidably mounted on the connecting rod 15f, the driven head 13, the front holder 15h, the guide sleeve 15g, the front resin buffer material 15j, etc. gradually slide in a direction away from the undercutter driving unit 12, that is, upward and to the left in Figure 7(a).

[0048] As a result, the front holder 15h, guide sleeve 15g, etc. separate from the rear resin buffer material 15m, which was sandwiched between the guide sleeve 15g and the rear guide 15e and abutted against both, and a gap G2 appears between the rear resin buffer material 15m and the guide sleeve 15g, as shown in Figure 7(a), and gradually increases in size.

[0049] As a result, in the state shown in Figure 7(a), similar to the state before the chain belt 11 is attached shown in Figure 6(a), the distance between the rear holder 15d and the front holder 15h widens, creating a gap G between the guide sleeve 15g and the rear resin cushioning material 15m, and the rear resin cushioning material 15m is no longer able to absorb vibrations or impacts.

[0050] However, even when a gap G occurs between the rear resin buffer material 15m and the guide sleeve 15g, the front resin buffer material 15j is provided between the driven head slide frame 13a of the driven head 13 and the front holder 15h, so that small vibrations and shocks from the driven head 13 are absorbed by the front resin buffer material 15j, and the front resin buffer material 15j can reduce the vibrations and shocks transmitted from the driven head 13 to the coil spring 15i, and the coil spring 15i can also absorb the vibrations and shocks generated in the driven head 13.

[0051] (Resetting up the cylinder part 15a of the tension adjustment part 15) As described above, when the gap between the rear holder 15d and the front holder 15h widens as shown in Figure 7(a), a gap G2 occurs between the guide sleeve 15g and the rear resin cushioning material 15m, and it becomes impossible to expect the rear resin cushioning material 15m to absorb vibrations or impacts, the undercutter device 1 of this embodiment resets the cylinder portion 15a of the tension adjustment unit 15.

[0052] Specifically, grease is injected from the grease nipple 15a2 of the cylinder portion 15a, and the piston rod 15b is extended from the cylinder portion 15a as shown in FIG. 7(b), thereby pushing out the rear holder 15d and rear guide 15e in the direction of the arrow α.

[0053] Then, the coil spring 15i sandwiched between the front holder 15h and the rear holder 15d contracts as the rear holder 15d slides in the direction of the arrow α, and the rear resin cushioning material 15m that was in contact with the rear guide 15e slides toward the guide sleeve 15g, gradually reducing the gap G2 that had occurred between the guide sleeve 15g and the rear resin cushioning material 15m. Eventually, as shown in Figure 7(b), the gap G2 becomes "0" and the rear resin cushioning material 15m comes into contact with the guide sleeve 15g, becoming sandwiched between the guide sleeve 15g and the rear guide 15e.

[0054] In other words, in the state shown in Fig. 7(b), grease is injected from the grease nipple 15a2, which is a reset of the cylinder portion 15a of the tension adjustment unit 15, causing the piston rod 15b to extend from the cylinder portion 15a and protrude to a protrusion length L2 (>L1), so that the rear resin buffer material 15m is sandwiched between the guide sleeve 15g and the rear guide 15e, as in the case shown in Fig. 6(b). Note that when transitioning from the state shown in Fig. 7(a) to the state shown in Fig. 7(b), the piston rod 15b is extended from the cylinder portion 15a by "L2 - L1."

[0055] Therefore, in the reset state shown in Figure 7(b), similar to when the chain belt 11 shown in Figure 6(b) is attached and excavation work is started, the front resin buffer material 15j between the driven head slide frame 13a of the driven head 13 and the front holder 15h absorbs small vibrations and impacts from the driven head 13, and since the coil spring 15i is still in a state where it can contract as shown in Figure 7(b), the rear resin buffer material 15m sandwiched between the guide sleeve 15g and the rear guide 15e, together with the coil spring 15i, absorbs vibrations and impacts acting in the longitudinal (axial) direction of the connecting rod 15f that could not be fully absorbed by the front resin buffer material 15j. As a result, the vibration of the entire undercutter device 1 is reduced, making the chain belt 11 less likely to loosen, and improving the workability of the trackbed excavation work.

[0056] <Summary of the undercutter device 1 according to the embodiment of the present invention> As described above, the undercutter device 1 according to the embodiment of the present invention comprises the chain belt 11 on which a plurality of excavation blades 12 for excavating the track bed are successively provided, the undercutter drive unit 12 for rotating the chain belt 11, the driven head 13 provided opposite the undercutter drive unit 12 and having the driven gear 13d around which the chain belt 11 is wound, and the cutter body 14 having the tension adjustment unit 15 for adjusting the tension of the chain belt 11 by pushing the driven head 13 away from the undercutter drive unit 12, and the tension adjustment unit 15 is a piston The device has a cylinder section 15a that extends and retracts the rod 15b, a connecting rod 15f that is provided at the tip of the piston rod 15b and to which the driven head 13 is slidably connected, a coil spring 15i that is provided around the connecting rod 15f so that the connecting rod 15f passes between the piston rod 15b and the driven head 13 and that constantly presses the driven head 13 away from the undercutter driving section 12, and a front resin buffer material 15j that is provided slidably relative to the connecting rod 15f so that the connecting rod 15f passes between the coil spring 15i and the driven head 13.

[0057] Therefore, even when the chain belt 11 stops or if an excessive load is placed on the chain belt 11 causing it to suddenly stop, the front resin buffer material 15j provided between the coil spring 15i and the driven head 13 absorbs vibrations and shocks generated in the entire undercutter device 1, which includes the chain belt 11, driven head 13, cutter main body 14, etc., making it less likely for the chain belt 11 to become loose.

[0058] As a result, the frequency (number of times) of the resetting work of extending the piston rod 15b by re-injecting grease from the grease nipple 15a2 can be reduced, thereby improving the work efficiency.

[0059] Furthermore, in the undercutter device 1 of the embodiment according to the present invention, the connecting rod 15f is fixed to the piston rod 15b via a rear holder 15d having a larger diameter than the connecting rod 15f, the coil spring 15i is provided between the front holder 15h, which has a larger diameter than the connecting rod 15f and is provided slidably on the connecting rod 15f, and the rear holder 15d, and the front resin buffer material 15j is provided between the front holder 15h and the driven head slide frame 13a of the driven head 13 via a back plate 15k.

[0060] Therefore, the front resin cushioning material 15j can directly absorb and cushion the vibrations and impacts from the driven head 13 through the back plate 15k without going through the coil spring 15, making it possible to absorb the vibrations and impacts transmitted to the coil spring 15i and the entire cutter main body 14, which also makes it less likely for the chain belt 11 to become loose.

[0061] In addition, in the undercutter device 1 of the embodiment according to the present invention, a back plate 15k made of a metal steel plate is provided between the front resin buffer material 15j and the driven head 13, and the cross-sectional shapes of the front resin buffer material 15j, the front holder 15h and the back plate 15k are formed so that the lower part is wider than the upper part.

[0062] Therefore, the longitudinally shaped undercutter device 1 tends to have the driven head 13 side, which is the tip, sag, and the back plate 15k is subjected to greater loads, vibrations, shocks, etc. at the bottom than at the top, but the cross-sectional shape of the front resin buffer material 15j is formed wider at the bottom than at the top to match the cross-sectional shape of the back plate 15k, making it easier to absorb vibrations, shocks, etc. transmitted to the entire cutter body 14 and making it less likely for slack to occur in the chain belt 11. As a result, this also reduces the number of times the piston rod 15b needs to be re-set up by re-injecting grease from the grease nipple 15a2 to extend it, improving work efficiency.

[0063] In addition, in the undercutter device 1 according to the embodiment of the present invention, to The holder 15h is provided with a cylindrical guide sleeve 15g through which the connecting rod 15f passes and extends toward the rear holder 15d, and which is attached to the connecting rod 15f together with the front holder 15h so as to be slidable relative to the connecting rod 15f, while the connecting rod 15f passes between the rear holder 15d and the guide sleeve 15g so as to be slidable relative to the connecting rod 15f, and when the gap between the front holder 15h and the rear holder 15d narrows, a rear resin buffer material 15m is provided which abuts against both the guide sleeve 15g fixed to the front holder 15h and the rear guide 15e fixed to the rear holder 15d, and which, together with the coil spring 15i, absorbs vibrations, impacts, etc. generated throughout the undercutter device 1.

[0064] Therefore, when rear resin buffer 15m is sandwiched between guide sleeve 15g and rear guide 15e and used or reset in this state, vibrations and shocks acting in the longitudinal (axial) direction of connecting rod 15f that were not fully absorbed by front resin buffer 15j are absorbed by rear resin buffer 15m together with coil spring 15i, and vibrations and shocks transmitted from driven head 13 to coil spring 15i are further reduced, making it harder for chain belt 11 to loosen by the amount that rear resin buffer 15m absorbs vibrations and shocks. As a result, the number of resetting operations in which piston rod 15b is extended by re-injecting grease through grease nipple 15a2 can be reduced, thereby improving work efficiency.

[0065] In the above embodiment, a front resin cushioning material 15j and a rear resin cushioning material 15m are provided, but the present invention is not limited to this, and it is of course possible to omit the rear resin cushioning material 15m and provide only the front resin cushioning material 15j.

[0066] In addition, in the description of the above embodiment, the rear guide 15e, which is separate from the rear guide 15d, is fixed to the rear holder 15d with the screw 15d1, and the guide sleeve 15g is fixed to the front holder 15h with the screw 15g1, so that the rear resin cushioning material 15m abuts against and is sandwiched between the guide sleeve 15g and the rear guide 15e. However, the present invention is not limited to this, and it is of course also possible to configure the rear holder 15d and the rear guide 15d, and the front holder 15h and the guide sleeve 15g as one unit, so that the rear resin cushioning material 15m abuts against and is sandwiched between a part of the rear guide 15d of the rear holder 15d and a part of the guide sleeve 15g of the front holder 15h. [Explanation of symbols]

[0067] 1 Undercutter device 11 Chain Belt 11a Drilling blade 11b scraping plate 12 Undercutter drive unit 13 Driven Head 13a Driven head slide frame 13a1 Rear end plate 13a11 Connection hole 13b Head upper plate 13b1 Gap cover plate 13c Head lower plate 13d Driven gear 14 Cutter body 14a Upper plate of cutter body 15 Tension adjustment section 15a Cylinder section 15a1 Cylinder connection part 15a2 grease nipple 15b Piston rod 15b1 Stone rod connection part 15c Guide bush holder 15c1, 15c2 guide bush 15d rear holder 15d1 screw 15e rear guide 15f Connecting rod 15f1 Connecting part 15g guide sleeve 15g1 Oiles bushing 15g2 large diameter annular section 15g3 screws 15h Front Holder 15i coil spring 15j Front resin cushioning material (front cushioning material) 15k backplate 15m Rear resin cushioning material (rear cushioning material)

Claims

1. A chain belt with multiple continuous excavation blades that excavate the roadbed, an undercutter drive unit that rotates the chain belt; a driven head that is provided opposite the undercutter drive unit, has a driven gear around which the chain belt is wound, and changes the direction of the chain belt; a cutter body having a tension adjustment unit that adjusts the tension of the chain belt by pushing the driven head away from the undercutter driving unit, The tension adjustment unit is a cylinder portion that extends and retracts the piston rod; a connecting rod provided at a tip end of the piston rod and to which the driven head is slidably connected; a coil spring provided between the piston rod and the driven head, which constantly presses the driven head away from the undercutter driving unit; an undercutter device comprising a front buffer material provided between the coil spring and the driven head for absorbing vibrations transmitted from the driven head;

2. 2. The undercutter device of claim 1, the connecting rod is fixed to the piston rod via a rear holder having a diameter larger than that of the connecting rod, the coil spring is provided between a front holder and a rear holder, the front holder having a diameter larger than that of the connecting rod and being slidably provided on the connecting rod; The undercutter device is characterized in that the front buffer material is provided between the front holder and the driven head so as to be slidable relative to the connecting rod, with the connecting rod passing through the front buffer material.

3. 3. The undercutter device according to claim 2, a back plate made of a metal steel plate is provided between the front buffer material and the driven head, An undercutter device, characterized in that the cross-sectional shapes of the front buffer material, the front holder, and the back plate are formed so that the width is wider at the bottom than at the top.

4. In the undercutter device according to claim 2 or claim 3, moreover, The front holder is provided with a cylindrical guide sleeve through which the connecting rod passes and which extends toward a rear guide provided on the front holder side of the rear holder, and which is attached slidably with respect to the connecting rod together with the front holder; An undercutter device characterized in that the connecting rod passes between the guide sleeve and the rear guide and is attached so as to be slidable relative to the connecting rod, and when the gap between the front holder and the rear holder narrows, a rear buffer material is provided that abuts against both the guide sleeve and the rear guide to absorb vibrations or impacts.

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