WO2018056889A1 - Machine d'installation de conduits/câbles dans des micro-tranchées - Google Patents

Machine d'installation de conduits/câbles dans des micro-tranchées Download PDF

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Publication number
WO2018056889A1
WO2018056889A1 PCT/SE2017/050916 SE2017050916W WO2018056889A1 WO 2018056889 A1 WO2018056889 A1 WO 2018056889A1 SE 2017050916 W SE2017050916 W SE 2017050916W WO 2018056889 A1 WO2018056889 A1 WO 2018056889A1
Authority
WO
WIPO (PCT)
Prior art keywords
saw blade
machine
stabilizing device
cables
layer
Prior art date
Application number
PCT/SE2017/050916
Other languages
English (en)
Inventor
Conny Gustavsson
Hasse Hultman
Original Assignee
Dellcron Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dellcron Ab filed Critical Dellcron Ab
Publication of WO2018056889A1 publication Critical patent/WO2018056889A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28D—WORKING STONE OR STONE-LIKE MATERIALS
    • B28D1/00—Working stone or stone-like materials, e.g. brick, concrete or glass, not provided for elsewhere; Machines, devices, tools therefor
    • B28D1/18—Working stone or stone-like materials, e.g. brick, concrete or glass, not provided for elsewhere; Machines, devices, tools therefor by milling, e.g. channelling by means of milling tools
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28D—WORKING STONE OR STONE-LIKE MATERIALS
    • B28D7/00—Accessories specially adapted for use with machines or devices of the preceding groups
    • B28D7/02—Accessories specially adapted for use with machines or devices of the preceding groups for removing or laying dust, e.g. by spraying liquids; for cooling work
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F5/00—Dredgers or soil-shifting machines for special purposes
    • E02F5/02—Dredgers or soil-shifting machines for special purposes for digging trenches or ditches
    • E02F5/10—Dredgers or soil-shifting machines for special purposes for digging trenches or ditches with arrangements for reinforcing trenches or ditches; with arrangements for making or assembling conduits or for laying conduits or cables
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F5/00—Dredgers or soil-shifting machines for special purposes
    • E02F5/02—Dredgers or soil-shifting machines for special purposes for digging trenches or ditches
    • E02F5/14—Component parts for trench excavators, e.g. indicating devices travelling gear chassis, supports, skids
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/46—Processes or apparatus adapted for installing or repairing optical fibres or optical cables
    • G02B6/50—Underground or underwater installation; Installation through tubing, conduits or ducts
    • G02B6/504—Installation in solid material, e.g. underground
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F5/00—Dredgers or soil-shifting machines for special purposes
    • E02F5/02—Dredgers or soil-shifting machines for special purposes for digging trenches or ditches
    • E02F5/08—Dredgers or soil-shifting machines for special purposes for digging trenches or ditches with digging wheels turning round an axis
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
    • H02G1/00—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines
    • H02G1/06—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines for laying cables, e.g. laying apparatus on vehicle

Definitions

  • the present invention relates to a machine for sawing micro trenches and placing ducts/cables in micro trenches.
  • the method for sawing micro trenches "Micro Trenching" is expected to become the dominating method for building Fiber-To-The-Home (FTTH) in areas with detached or semi- detached houses.
  • FTTH Fiber-To-The-Home
  • In Sweden around 400 000 houses are expected to become connected to a fiber network during the next 5 - 10 years.
  • the world market is enormous and may be estimated to around 100 - 500 times the Swedish market. This means that somewhere between 40 million to 200 million houses may become connected over the next 20 years.
  • a road sawing machine is used for sawing the trenches in which ducts/cables will be placed.
  • An object of the present invention is to provide a machine for sawing micro trenches and placing ducts/communication cables, which fully or in part solves the problems and drawbacks of prior art solutions.
  • the present invention relates to a machine arranged for sawing micro trenches and placing ducts/cables in micro trenches, wherein said machine comprises:
  • a saw blade arranged for sawing a micro trench in an area through a first layer and into a second layer, wherein said first layer is a hard surface layer and said second layer is a bearing layer for said first layer and being positioned below said first layer;
  • a stabilizing device arranged for stabilizing the sides of said micro trench when placing said ducts/cables in said micro trench completely below said first layer by means of guiding means, wherein a front part of said stabilizing device, when placing said ducts/cables in said micro trench, is positioned immediately behind said saw blade and has a shape that is mainly complementary to the shape of said saw blade, and wherein said stabilizing device further comprises one or more nozzles arranged for cooling said saw blade.
  • the present machine can comprise: at least one nozzle arranged for cooling said saw blade using cooling water; or at least one nozzle arranged for cooling said saw blade using cooling air; or at least one nozzle arranged for cooling said saw blade using cooling water and at least one nozzle arranged for cooling said saw blade using cooling air.
  • An advantage with the machine according to the invention is its superior ability for cooling the saw blade, especially diamond segments of a saw blade.
  • the effective cooling gives the saw blade much longer life compared to prior art solutions, which in turn reduces the installation cost.
  • lubrication is also provided leading to even less ware on the saw blade.
  • Figure 2 shows a flow chart of an embodiment of MTT
  • Figure 3a and 3b schematically shows a cross section of an area in which a micro trench 1 has been sawed through a hard surface layer LI of asphalt or concrete and into an underlaying bearing layer L2 comprising sand, gravel and stones;
  • Figure 4 schematically shows the cross section in figure 3, wherein the micro trench 1 is filled with filling material 6 such as sand and sealed with two sealing layers;
  • Figure 5 shows a typical layout of a FTTH network
  • Figure 6 shows how to saw branches to individual homes from a main micro trench 7
  • Figure 7 shows branching to individual homes if guided boring is used instead of sawing
  • Figure 8 shows a sawing machine 8 with its saw blade 14 and a stabilizing device 13 for placing ducts/cables 2/3 immediately behind the saw blade 14.
  • Figure 8 also shows a feeding device 36, such as a pump/compressor for cooling water/air, that through a hose 30 is pumping water/air to nozzles 31 on and/or in the stabilizing device 13;
  • Figure 9 shows a sawing machine 8 where the stabilizing device 13 is adapted for placing a plurality of ducts/cables 2/3 at the same time while maintaining the order of the ducts/cables 2/3 in the micro trench 1;
  • Figure 10 shows in detail where to cut the top duct 2 so that it will be long enough to reach its final destination
  • Figure 11A shows a core blade 32 attached with segments containing diamonds or alternatively hard metal bits along its periphery.
  • the core blade 32 has holes 27 for attachment to the machine 8 and holes 29 for mounting several blades 32 or 33 and slits blades 34 or 35 together for the formation of a saw blade 14.
  • the core blade 32 has a number of holes 28 for a cooling medium such as water.
  • Figure 11B shoves a core blade 33 attached with segments containing diamonds or alternatively hard metal bits along its periphery.
  • the core blade 33 has holes 27 for attachment to the machine 8 and holes 29 for mounting several blades 32 or 33 and slits blades 34 or 35 together for the formation of a saw blade 14.
  • Figure 12A shows a slits blade 34 with holes 27 for attachment to the machine 8 and holes 29 for mounting slits blade/blades 34 and blades 32 or 33 together for the formation of a saw blade 14.
  • Figure 12B shows a slits blade 35 of similar implementation as the blade in figure 12A, but containing milled grooves (indicated with dotted lines) for the transportation of a cooling medium such as water from the machine's 8 drive shaft to the space between the arms of the slits blade 35.
  • a cooling medium such as water
  • Figure 13 shows an alternative implementation of a slits blade according to 34 or 35
  • Figure 14 shows how a blade 32 and a slits blade 34 are working together for the transportation of cooling water, coming from the holes 28 to the space between the arms of the slits blade 34 and thereafter, with the help of the centrifugal force, further out towards the periphery of the blade 32
  • Figure 15 shows a stabilizing device 13, consisting of two parts, one fixed section 41 and one flexible section 42.
  • the fixed section 41 is attached to the machine and the flexible section 42 is attached to the fixed section 41 via a flexible joint for example a hinge.
  • the fixed section 41 has nozzles 31 arranged for cooling water or air.
  • the cooling water/air is transported by a hose 30 from a feeding device 36, such as a pump/compressor for cooling water/air to at least one nozzle.
  • the present invention relates to a sawing machine 8 comprising a saw blade 14 arranged for sawing micro trenches 1 in an area.
  • the machine 8 further comprises a stabilizing device 13 arranged for stabilizing the walls of the micro trench 1 when placing ducts/cables 2/3 into the same.
  • the stabilizing device 13 is positioned immediately behind the saw blade 14 in the micro trench 1 and comprises guiding means 17 for guiding at least one duct/cable 2/3 when placed into the micro trench 1.
  • the saw blade 14 and corresponding stabilizing device 13 may be integrated with the sawing machine 8 and thereby forming a completely new machine type or designed as an attachment unit that can be attached to existing machines.
  • the saw blade 14 and stabilizing device 13 may be placed on the right side of the machine 8 or on the left side. Other possible locations are in front of the machine 8 or behind.
  • the following description relates to all possible locations of the saw blade 14 and stabilizing device 13 as the description only talks about the relative position of the stabilizing device 13 in relation to the saw blade 14.
  • the saw blade 14 may either be composed of a single sawing disk, consisting of a core blade 32, 33 with segments containing diamonds welded or brazed along its periphery or the saw blade 14 is composed of a number of sawing disks separated by slits blades 34, 35.
  • a slits blade 34 or 35 may be implemented in several ways and may have several functions. One of the functions is to form a space between the core blades 32, 33 in a saw blade 14 composed by several sawing disks. Another function is to make it possible for a cooling medium such as water and/or air to pass between the arms of the slits blades 34, 35. A third function is to help transport sawed material away from the micro trench 1.
  • the slits blades 34, 35 between the core blades 32, 33 form a channel system in a composite saw blade 14, from as close to the center as possible and out towards the periphery, in such a way that that cooling of the composed saw blade 14 is possible.
  • a composite saw blade 14 may also be composed by having every second core blade 32, 33 with welded or brazed hard metal bits and every second core blade 32, 33 with welded or brazed segments containing diamonds along their peripheries, all being separated by slits blades 34, 35.
  • a composite saw blade 14 may either be composed by two or more core blades 32, 33 with segments containing diamonds and separated by slits blades 34, 35 or be composed by having every second core blade 32, 33 with segments containing diamonds and every second core blade 32, 33 with hard metal bits, and all core blades 32, 33 being separated by slits blades 34, 35.
  • the outermost two core blades 32, 33 shall be equipped with segments containing diamonds.
  • a saw blade 14 composed by a number of core blades 32, 33 separated by a distance of suitable size will require less energy when sawing a micro trench 1 of a certain width compared with a saw blade 14 with only one core blade 32, 33.
  • a saw blade 14 with only one core blade 32, 33 must pulverize all material to fine dust, while a composite saw blade 14 only pulverizes some of the material.
  • the distance between the core blades 32, 33 in a composite saw blade 14 is not too large, the material from stones and other sawed through material will be pulverized by the diamond segments, while the material that goes into the spaces between the core blades 32, 33 will either be broken into smaller pieces and thrown out as grains with larger grain size or as whole slab disks from the stone sawed through.
  • the distance between core blades 32, 33 in a composite saw blade 14 will to some extent determine the grain size in the sawed up material.
  • Slits blades 34, 35 normally have less diameter compared with the diameter of the core blades 32, 33 after attachment of segments containing diamonds or alternatively hard metal bits.
  • a slits blade 34, 35 may have a thickness of 1 - 10 mm depending on the combination of material in the bearing layer L2.
  • the core blades 32, 33 and slits blades 34, 35 may be assembled to a saw blade 14, with the aid of gluing, spot welding or by rivets or screws or a combination of these methods. Spot welding may result in a bending of the saw blade 14.
  • the saw blade 14 may have to be cooled by a cooling medium such as water or air in order to avoid overheating and in order to reduce the wear and thereby increase its life.
  • Cooling water may have four functions: reduce the friction between the saw blade 14 and the sides of the micro trench 1, reduce the wear on the outer sides of the core blades and on the segments containing diamonds, cool the saw blade 14, and prevent sawing dust from coming out in the environment.
  • a saw blade 14 with at least two core blades 32, 33 separated by slits blades 34, 35 water can pass between the blades 32, 33 and between the arms of the slits blades 34, 35 so that the whole saw blade 14 will be cooled.
  • Cooling medium such as water is supplied either through the machine's 8 drive shaft for the saw blade 14 and passed through milled groves (indicated with dotted lines in figure 12B) in slits blades 35 and out into the space between the arms of the slits blades 35 and further out towards the periphery of the saw blade 14.
  • An alternative method to supply cooling water is to spray water towards the holes 28 from nozzles mounted in the protective cover (not shown) over the saw blade 14. Some of this water will pass through the holes 28 and then with the aid of the centrifugal force, be transported between the arms of the slits blades 34, 35 out towards the periphery of the saw blade 14. The water not passing the holes 28 will lubricate and cool the two outer sides of the saw blade 14.
  • FIG 8 and 15 Yet another way of supplying cooling water to the saw blade 14 is shown in figure 8 and 15.
  • the machine 8 is provided with at least one nozzle 31 placed in and/or on the stabilizing device 13.
  • the purpose of this at least one nozzle 31 is mainly to apply/spray water or air on the diamond segments of the saw blade 14 and thereby reduce the wear of the same.
  • These nozzles 31 are also valuable when the saw blade 14 is a composite saw blade 14 containing more than two core blades 32, 33. Then, supplying water to the inner core blades 32, 33 is normally a problem.
  • One solution is the placement of one or more nozzles 31 on the stabilizing device 13 and being directed towards the segments on the core blades 32, 33 as shown in Figure 15.
  • nozzles 31 supply water when the stabilizing device 13 is below ground level 10.
  • the one or more nozzles 31 are arranged on the front part 18 of the stabilizing device 13. At least one nozzle 31 may be arranged on or vertically above the front part 18 and vertically above the surface 10 of the first layer LI during operation, whilst one or more other nozzles 31 are arranged on the front part 18 of the stabilizing device 13 and below the surface of the first layer LI during operation. All nozzles 31 are directed towards the saw blade in Figure 15.
  • the nozzles 31 arranged on the front part 18 are in one embodiment at least partially arranged inside the stabilizing device 13 together with the hose 30.
  • Water for cooling and lubrication should be supplied using at least one of the above mentioned methods. However a combination of all mentioned methods can be used. The amount of water must be carefully controlled. Too much water and the micro trench 1 will collapse and thereby make sawing and installation difficult. Too little water will make the life time of the saw blades 14 too short and thereby increasing the costs. Cooing air is an alternative to water for cooling of the saw blade 14. This is specially advantageous in certain environments where it is a requirement to saw completely dry. The saw blade 14 will by itself act as a fan, when rotating with high speed inside the protective cover. In addition, it is possible to obtain an airflow between the blades 32, 33 in a saw blade 14, through suitable designed blades 32, 33 and slits blades 34, 35.
  • the slits blades 34, 35 between the blades 32, 33 in a saw blade 14 can be designed to obtain a strong airflow between the core blades 32, 33 from holes near the center of the saw blade 14 and out through the space between the core blades 32, 33. These two airflows may be enough to cool the core blades 32, 33.
  • the combined airflow from the two sources may help transporting the sawed up material, so that it can be guided out from the protective cover in a controlled way and thereby for example more easily be collected in a suitable container.
  • air intakes can be arranged in the protective cover on both sides of the saw blade 14 and placed in X- and Z-direction (X-direction is in the sawing direction 9, Y-direction is sideways, and Z- direction is vertical) near the center of the saw blade 14 when it is in its working position. If this airflow is not sufficient, it can be increased by two methods.
  • One solution is to add air from a compressor. The air can be supplied through nozzles 31 on the front of the stabilizing device 13, under or just over ground level 10, in a similar way as described for water.
  • Another solution could be to attach a strong suction device (not shown in the Figs.), that increases the airflow by sucking out air from the protective cover over the saw blade 14.
  • This suction device should be attached in the front of the protective cover and just over ground level 10 and having a near vertical outlet or an outlet directed upwards at a slightly forward angle. This in order to make the transport of sawed up material easier.
  • Being able to use both water and air at the same time and having the ability to continuously control the respective flow is advantageous when cooling the saw blade 14.
  • the saw blade 14 and stabilizing device 13 are raised above ground level 10 it may be advantageous to reduce the flow of water and increase the flow of air.
  • the machine 8 may be equipped with a high pressure pump for water and nozzles inside the protective cover.
  • the nozzles may be arranged to provide a straight aimed jet of water or a flat jet.
  • the pump may give a pressure of 160 Bar. However, the pressure may be lower or higher than 160 Bar as required for cooling the saw blade.
  • the pump can be adjusted for pulsating or continuous flow of water and it is driven hydraulically or electrically.
  • the pump may also be controlled by a control unit connected to sensors that sense the amount of material stuck inside the protective cover and starts the high pressure pump when the amount of material exceeds a certain value or the high pressure pump may be started with specific time intervals. When the high pressure pump is in operation the material stuck inside the protective cover is flushed out.
  • the protective cover may also be equipped with a vibrator to make it easier for the material stuck inside the protective cover to come loose.
  • the vibrator may be arranged by having an electrical engine with an eccentrically arranged weight on its shaft.
  • the saw blade 14, and the stabilizing device 13 are individually or jointly height adjustable between a highest position (i.e. "transport position") completely above ground level 10 and a lowest position (i.e. "operating position") up to 500 mm below ground level 10.
  • the movement of the saw blade 14 between the two extreme positions may be vertical or near vertical or a rotation movement.
  • a vertical or near vertical movement may for example be achieved by having the movement of the saw blade 14 guided by one or more vertical or near vertical linear bearings or slides.
  • a rotation movement may be achieved by the saw blade 14 and its engine being attached using a hinge in one end and a lifting device in the other end. Thereby the saw blade 14 can be elevated and lowered with a rotation movement with the aid of the lifting device.
  • the movement of the stabilizing device 13 is more complicated. During the transition between the two extreme positions the stabilizing device 13 may not touch the saw blade 14 or the bottom of the micro trench 1 or the protective cover over the saw blade 14. In addition, as the elevation and lowering of the stabilizing device 13 may be performed while cables 3 and/or ducts 2 are inserted in the guiding means 17 in the stabilizing device 13, the design must provide enough clearance and ensure that minimum bending radius for ducts 2 and cables 3 are possible to keep within specified limits. In its highest position the stabilizing device 13 is completely lifted above ground level 10 and with some ground clearance. In its lowest position the stabilizing device 13 is max 50 mm above bottom of the micro trench 1 and positioned immediately behind the saw blade 14 with a clearance of max 20 mm.
  • the saw blade 14 wears and thereby its diameter will decrease. This means that the distance between the saw blade 14 and the stabilizing device 13 will increase with time. At some point in time the distance may be large enough so that stones in the bearing layer may cause the stabilizing device 13 to get stuck in the micro trench 1. Therefore, the link arms that performs the movement of the stabilizing device 13 as well as their anchor points in the sawing machine 8 must be very strong. This is important because if the stabilizing device 13 is stuck in the micro trench 1 for some reason, substantial forces may be applied to the stabilizing device 13 and to its lifting system and anchor points in the sawing machine 8. To compensate for the wear of the saw blade 14 it is necessary to have the position of the stabilizing device 13 adjustable with reference to the current saw blade 14 radius. The adjustment can be implemented using turnbuckles or similar devices or by separate engine devices.
  • the saw blade 14 diameter is reduced by up to approximately 40 mm during its life i.e. the radius is decreased by up to 20 mm. For this reason the distance between the saw blade 14 and the stabilizing device 13 should be adjusted to less than 5 mm with a new and unused saw blade 14. In this way the distance need only be adjusted one more time during the life of the saw blade 14.
  • the stabilizing device 13 must during operation be carefully positioned immediately behind the saw blade 14 in X, Y and Z- direction as well as inclination angle in the X-Z-plane and Y-Z- plane (X-direction is in the sawing direction 9, Y-direction is sideways and Z-direction is vertical).
  • Adjustment in Y-direction can either be made by moving the stabilizing device 13 or the saw blade 14. Adjustment of the saw blade 14 in Y-direction may be made by using shim washers of different sizes between the machine 8 mount and the saw blade 14, while adjustment of the stabilizing device 13 in Y-direction can be made using suitably positioned adjustment screws. In the same way adjustment of the stabilizing device 13 in X-direction, Z-direction as well as inclination angle in the X-Z-plane and Y-Z-plane can be implemented.
  • a sufficiently accurate adjustment of the stabilizing device 13 in X-direction, inclination angle in X-Z-plane as well as height in Z-direction is achieved when the distance to the saw blade 14 is max 20 mm and as evenly distributed as possible over the whole underground height of the stabilizing device 13 and the X-direction of the fixed part of the stabilizing device 13 should be less than 1 degree from the direction of the saw blade 14.
  • laser pointers or a ruler may be of good help.
  • the adjustment may also be made automatically by arranging engine devices on the adjustment screws. Then, together with suitably positioned sensors the adjustment may be made automatically.
  • the link arms for elevation and lowering of the stabilizing device 13 are powered by a dedicated engine device (e.g. electrical or hydraulic).
  • a machine 8 with the saw blade 14 arranged on the side of the machine 8 may have on its left and right sides, in the sawing direction 9, quick mount attachments means and driving means for both the stabilizing device 13 and the saw blade 14, respectively.
  • any of the left or right sides of the sawing machine 8 can be used for sawing and placing ducts/cables 2/3 which may be necessary due to hindering infrastructure, traffic situation in the areas, etc.
  • the movement of the stabilizing device 13 may be controlled mechanically by link arms with fixed anchor points and performed using a single electrical or hydraulic engine device or by a number of electrical or hydraulic engine devices under software control from a computer.
  • the saw blade 14 is positioned in its highest position for example during transportation when the sawing machine 8 is moved to a new geographic position and a trench is not sawn during the transportation.
  • the saw blade 14 is also in its highest position during saw blade 14 replacement.
  • the protective cover over the saw blade 14 is opened over the whole side of the cover so that the whole saw blade 14 is accessible.
  • the stabilizing device 13 is in its highest position during transportation and during the threading of all ducts/cables 2/3 and during the start of the micro trenching.
  • the saw blade 14 is first lowered to its operating position and the sawing machine 8 is advanced around 1 - 2 m so that there is room in the trench 1 to lower the stabilizing device 13.
  • the stabilizing device 13 may either be openable arranged or the stabilizing device 13 is fitted with an openable cassette so that ducts/cables 2/3 easily can be laid down in their respective channels.
  • An openable cassette that can be removed from and attached to the stabilizing device 13 will save time in some cases e.g. when the micro trenching and installation of ducts/cables 2/3 is temporarily interrupted for some reason and restarted at a later time e.g. the next day from the same location.
  • the removable cassette may be attached to the stabilizing device 13 by means of a hinge with a removable pivot. When the pivot has been removed, the cassette can easily be removed.
  • the cassette can also be left in the micro trench 1 when the sawing machine 8 is moved to another location using the following method: remove the pivot and advance the sawing machine 8 a few centimeters so that the stabilizing device 13 without the cassette can be lifted. To reattach the cassette to the stabilizing device 13 the opposite maneuver is performed.
  • a stabilizing device 13 with two sections, flexible jointed together makes sawing and installation of ducts/cables 2/3 around curves easier.
  • the joint may be the above mentioned hinge with a removable pivot or designed in any other way.
  • the flexible joint may have a maximum inclination angle of + 30 degrees from the Z-direction in the X-Z-plane.
  • a problem that may arise because of this is when the stabilizing device 13 is in its highest position, the flexible section 42 of the stabilizing device 13 may swing to the side and thereby prevent the stabilizing device 13 to be lowered into the micro trench 1.
  • This problem may be solved by arranging an elastic limitation on both sides of the flexible section 42 in such a way that it stands out straight when no outer forces are applied on it.
  • the elastic limitation When driving the machine 8 around curves with the stabilizing device 13 lowered, the elastic limitation will allow the flexible section 42 to be bent to the side as much as required, so that the stabilizing 13 device easily can be moved around the curve in the micro trench 1.
  • Such an elastic limitation may for example be made by mounting a conical device made of rubber on each side of the flexible section 42. The conical devices are mounted with their points towards each other and in contact with the flexible section 42. In this way you get a strongly increasing counterforce, when you try to bend the flexible section 42 to the side from its normal place straight out behind the fixed section 41 of the stabilizing device 13. This device will keep the flexible section 42 in its place straight behind the fixed section 41 of the stabilizing device 13 as long as no outer forces are applied to it.
  • the fixed section 41 of the stabilizing device 13 contains in its front the front part 18 as shown in Fig. 15.
  • the stabilizing device 13 may be arranged with a vibrator.
  • This vibrator may be designed as an electric engine with an eccentrically arranged weight on its shaft. Strong vibrations are created when power is applied to the engine.
  • the vibrator is arranged on the fixed section 41 of the stabilizing device 13 and above ground level 10.
  • the present machine 8 is arranged for sawing micro trenches 1 in an area.
  • the machine 8 comprises a saw blade 14, preferable circular in shape, for sawing/cutting the micro trenches 1.
  • the produced micro trenches 1 are adapted for receiving ducts/cables 2/3 which means that the micro trenches 1 has been given the proper dimensions.
  • the machine 8 also comprises a stabilizing device 13 arranged for stabilizing the walls of the micro trench 1 when placing ducts/cables 2/3, and for this purpose the stabilizing device 13 is positioned immediately behind the saw blade 14 in the micro trench 1, so that the walls are stabilized until the ducts/cables 2/3 have been placed/installed by means of guiding means 17 arranged on/in the stabilizing device 13.
  • the stabilizing device 13 comprises suitable stabilizing elements such as proper side elements which are arranged to "hold up" the walls until the ducts/cables 2/3 have been installed in the micro trench 1.
  • the stabilizing device 13 is positioned immediately behind the saw blade 14 so that the trench 1 sawn by the saw blade 14 is stabilized directly after it is produced so that it does not collapse, or that stones or debris fall to the bottom of the trench 1 before ducts/cables 2/3 have been placed. Therefore, according to an embodiment of the invention, the maximum distance between the saw blade 14 and the stabilizing device 13 is larger than 0 mm but less than 20 mm.
  • the dimension of the stabilizing device 13 is dependent on the size of the ducts/cables 2/3, the number of ducts/cables 2/3 to be placed at the same time, and the wanted depth for placement in the trench 1. However, the width of the stabilizing device 13 should be equal to or slightly less than the width of the sawing blade 14.
  • the stabilizing device 13 also comprises guiding means 17 which guides the ducts/cables 2/3 into the trench 1 in a controlled and ordered manner.
  • the combination of stabilizing and guiding has proved to reduce cost and time in an effective manner since the process of sawing and installing can be performed at the same time.
  • the guiding means 17 are arranged on/in the stabilizing device 13 and hence the invention makes it possible to place the ducts/cables 2/3 into the trench 1 while the trench 1 is stabilized by the stabilizing device 13.
  • the ducts/cables 2/3 can therefore be placed with high precision into the trench 1 (e.g. on the correct height in the trench 1) since the trench 1 is "clean" as long as the trench 1 is stabilized by the device 13.
  • the stabilizing device 13 may be made of any suitable hard material.
  • the material should preferably be rigid, tough, hard and yet flexible so as to withstand stress during operation.
  • the mounting of the stabilizing device 13 to the sawing machine 8 should have an amount of flexibility to prevent damage if the stabilizing device 13 is stuck in the trench 1.
  • Steel or steel alloys are suitable since they can be given the right properties by alloying with different metals such as platinum and manganese. There is limited space in the trench 1 so the walls of the stabilizing device 13 have to be thin as possible so as to be able to accommodate all of the ducts/cables 2/3 to be laid, but still have the properties mentioned above.
  • the stabilizing device 13 has an inlet 11 and an outlet 12 for ducts/cables 2/3, the inlet 11 and outlet 12 being connected to the guiding means 17.
  • the guiding means 17 are channels through which the ducts/cables 2/3 are guided through the stabilizing device 13.
  • the inlet 11 is preferably above ground level 10 and vertically or close to vertically arranged while the outlet 12 is below ground in the micro trench 1 and horizontally or close to horizontally arranged in order to minimize wear and tear on the ducts/cables 2/3.
  • the minimum horizontal distance at ground level 10 between the outlet 12 of the stabilizing device 13 and the saw blade 14 is slightly longer than the recommended minimum bending radius for the ducts/cables 2/3 to be installed, which means that the minimum distance is dependent on the recommended minimum bending radius. This normally translates to somewhere between 100 to 500 mm measured at ground level 10, but other distances are possible.
  • the inlet 11, outlet 12 and guiding means 17 may together be removably attached on the stabilizing device 13 e.g. in the form of a removable cassette. By having a removable cassette for the guiding means 17, the installation time shortens in some cases as the time consuming task of inserting many ducts/cables 2/3 into their respective channels may be avoided.
  • an operating depth for the stabilizing device 13 in the micro trench 1 can be up to 50 mm less than an operating depth for the saw blade 14 according to an embodiment.
  • This difference in operating depth between the saw blade 14 and the stabilizing device 13, determines how quickly the ground level 10 may change (i.e. go down).
  • the saw blade 14 must have sawed the trench 1 deep enough so that the stabilizing device 13 does not touch the bottom of the trench 1 in order to avoid the possibility of the stabilizing device 13 sticking to the bottom of the trench 1. This eliminates unnecessary forces on the stabilizing device 13 and possible breakage. This may happen when the ground level 10 suddenly becomes much lower.
  • the stabilizing device 13 and the saw blade 14 are arranged to be elevated and lowered independently of each other. This is advantageous when for example the saw blade 14 must be changed due to wear or when another type of saw blade 14 is needed (e.g. one type for asphalt and another type for concrete). Further, the stabilizing device 13 may have to be replaced which may easily be performed if the two parts can be lowered and elevated independently of each other. In addition, during shorter interruptions in the sawing operation the saw blade 14 is elevated, but the stabilizing device 13 must remain in the micro trench 1, since the need for stabilizing of the trench 1 still exists.
  • FIG 9 shows an embodiment of a machine 8 according to the invention.
  • the stabilizing device 13 has a front part 18 and a back part 19, wherein the front part 18 is located immediately behind the saw blade 14. It can also be seen that the stabilizing device 13 has a section at the front part 18 that has a shape that is mainly complementary to the shape of the saw blade 14, which in this particular case is circular. Thus, in this case the section at the front part 18 has a concave circular shape with the same radius, or close to the same radius, as a new and unworn saw blade 14 and is placed as close as possible and less than 20 mm away from the saw blade 14.
  • the reason for this is that the underground part of the stabilizing device 13 must be arranged so close to the saw blade 14 such that it is virtually impossible for dirt, stones and other debris to fall to the bottom of the trench 1 or wedge between the sides of the trench 1.
  • the guiding means 17 in this embodiment are channels inside the stabilizing device 13. The channels are illustrated with dotted lines in the figures.
  • the stabilizing device 13 may also be wedge/axe shaped in cross section at the front part 18 in the forward direction 9.
  • the saw blade 14 and the stabilizing device 13 must be replaced.
  • the stabilizing device 13 must have a shape that is mainly complimentary to the saw blade 14. Therefore, if the saw blade 14 is changed to a saw blade 14 with different radius the stabilizing device 13 must be replaced with one with a concave shape with near the same radius.
  • the lifting arms and/or their anchor points for lifting the stabilizing device 13 may have to be changed. This can be achieved by having adjustment screws or turnbuckles on the lifting arms and/or having other anchor points for the lifting arms prepared on the sawing machine 8.
  • the internal shape of the protective cover is optimized to the shape of the saw blade 14 in order to give maximum transport of the sawed up debris out through an opening in the front of the saw blade 14 cover. This internal shape may have to be changed, when the saw blade 14 is replaced with one with different diameter, in order to get optimal transport of debris.
  • the stabilizing device 13 has a maximum width in cross section that is equal to or slightly less than a width for the saw blade 14.
  • the stabilizing device 13 must be wide enough to have room for the ducts/cables 2/3 to be installed, but small enough so that it can be drawn forward in the sawed trench 1.
  • Another important aspect of the invention is that, with the use of guiding means 17 an order of a plurality of ducts/cables 2/3 is preserved when placed in the micro trench 1. This is very important when more than one duct/cable 2/3 is placed at the same time.
  • the duct/cable 2/3 for a certain property is cut at a certain distance 15 beyond the property. It is important that this duct/cable 2/3 is one of the ducts/cables 2/3 on top of the pile of ducts/cables 2/3 in the trench 1, so that it can be easily found.
  • the duct/cable 2/3 must be cut before the stabilizing device 13.
  • the stabilizing device 13 has a plurality of guiding means 17 each guiding one or a few ducts/cables 2/3 into the trench 1.
  • the stabilizing device 13 may comprise a plurality of channels so arranged that a known order is preserved, which means that an order of the ducts/cables 2/3 out of the stabilizing device 13 is known form the order of ducts/cables 2/3 into the stabilizing device 13, hence the order into and out of the stabilizing device 13 is related and known.
  • the order of the ducts/cables 2/3 should be arranged in such a way that one of the ducts/cables 2/3 on top of the pile of ducts/cables 2/3 in the trench 1 is always the one to be routed to the next destination.
  • Branching micro trenches may be sawn before the main micro trench 7 is sawn as shown in figure 6 and 7 or the branching micro trenches may be sawn after the main trench 7 is sawn. The particular order in which the trenches are sawn may be decided from case to case in order to achieve the best flow during the installation.
  • Each branching micro trench runs from the main micro trench 7 to a final destination and is made to receive the dedicated duct/cable 2/3 for that particular destination.
  • the duct/cable 2/3 about to become the top duct/cable 2/3 is cut before entering the stabilizing device 13 at a certain distance 15 beyond the location of the respective branching trench, so that that duct/cable 2/3 can be lifted from the main micro trench 7 and routed to its final destination through the branch, see figure 10. If the cut is made correctly 15 the length of the duct/cable 2/3 will be sufficient so that the duct/cable 2/3 is long enough to reach the final destination without splicing. In this way the ducts/cables 2/3 are one by one routed to each passed location through the branches.
  • ducts/cables 2/3 there may be one or more ducts/cables 2/3 side by side as the uppermost ducts/cables 2/3 in the main trench 7. It is important that the duct/cable 2/3 next to be routed to its final location is always one of the ones on top.
  • the duct/cable 2/3 when sawing the main trench 7 and placing a number of ducts/cables 2/3, the duct/cable 2/3 about to become one of the uppermost ducts/cables 2/3 in the micro trench 1, the one designated to the next predetermined destination, is cut before it enters the stabilizing device 13 at a certain distance 15 after passing the corresponding branching trench, so that that particular duct/cable 2/3 can be lifted and routed through the branching micro trench to its final destination.
  • the duct/cable 2/3 should be cut at a certain minimum distance 15 after passing the corresponding branching trench, so that, when lifted from the main trench 7 and routed towards its final destination, the length is sufficient to reach the final destination without splicing.
  • the stabilizing device 13 is designed with individual channels for each duct/cable 2/3 or with individual channels, each with room for a few ducts/cables 2/3, it is easy to know which duct/cable 2/3 will be on top in the trench 7 and thereby which duct/cable 2/3 should be cut before entering the stabilizing device 13.
  • Example of such stabilizing device 13 is shown in Figure 9.
  • the stabilizing device 13 in this embodiment has a duct/cable 2/3 inlet 11 and a duct/cable 2/3 outlet 12 connected to each other by means of a plurality of channels as guiding means 17 (illustrated with dotted lines) for the ducts/cables 2/3.
  • the underground outlet 12 of the stabilizing device 13 may in an embodiment comprise a "matrix" (or vector) part so arranged that the channels are arranged in a matrix with n rows and m columns, thereby in a controlled way horizontally and/or vertically separating the ducts/cables 2/3 when placing them in the micro trench 1.
  • the machine 8 may further comprise a device for holding at least one drum for ducts/cables 2/3 before placing them into the micro trench 1 via the stabilizing device 13. In this way easy access to the ducts/cables 2/3 is achieved.
  • the machine 8 may also comprise other suitable means, such as: one or more engine means for powering the saw blade 14, the stabilizing device 13 and/or driving means (e.g. caterpillar tracks or wheels), communication means for wireless communication with e.g. a remote server unit, processing means, memory means, sensors, GPS means, vehicle means, display means for displaying information such as graphics, data base means, reading means for reading mechanical coding means on the saw blades 14, immobilizer, etc.
  • suitable means such as: one or more engine means for powering the saw blade 14, the stabilizing device 13 and/or driving means (e.g. caterpillar tracks or wheels), communication means for wireless communication with e.g. a remote server unit, processing means, memory means, sensors, GPS means, vehicle means, display means for displaying information such as graphics, data base means, reading means for reading mechanical coding means on the saw blades 14, immobilizer, etc.
  • Mechanical driving gives the highest power transmission ratio while electrical driving gives the lowest, so the former is preferred if high power is needed which often is the case.
  • the machine 8 may be equipped with caterpillar tracks/bands over the wheels.
  • Such caterpillar tracks/bands may be regarded as an "own piece of road", which the machine 8 rolls out under itself.
  • the wheels of the machine 8 will therefore always be running on a "good piece of road”.
  • the width of the caterpillar track/band is much larger compared with that of the wheels and thereby the ground pressure will be spread out and therefore will be very low measured per surface area.
  • the restored trench 1 can often be seen as a dark stripe in the road or sidewalk.
  • the trench 1 In order for it to look good, aesthetically, the trench 1 must be very straight. It looks very bad if it is wobbling back and forth. Even a small deviation, as little as a few centimeters to each side, will look extremely bad. Therefore, the driver of the sawing machine 8 must devote a very large part of his attention to driving straight. It is therefore valuable if the sawing machine 8 has the ability to relieve the driver much of such trivial activities.
  • One method to do this is to incorporate a device on the machine 8, that steers the machine 8 more or less automatically with a precision of less than one centimeter.
  • One method to do this is to mount a straight forward looking video camera onto the machine 8.
  • This video camera is connected to a processing device that in turn, through a suitable servo, controls the steering of the machine 8.
  • the processing device stores a first image from the video camera. This image is taken from a portion in the center of the video image from the video camera. This image is then compared with subsequent images coming from the video camera. At certain intervals, for example every 10 images, the processing device makes correlation calculations where one of the images is shifted sideways one pixel at a time and the processing device is looking for a peak in the correlation between the two images. This peak in the correlation represents the largest correlation between the original image and the latter image. The number of pixels this correlation peak has been shifted sideways is a measure of the deviation from straight-ahead driving.
  • the reference image is automatically and periodically replaced with a more recent image.
  • the number of pixels the correlation peak has been shifted sideways is then used to, via the steering servo, steer the machine 8 back to "straight forward".
  • the precision can be made arbitrarily accurate for example through the use of different lenses on the video camera. A telephoto lens will give higher accuracy while a wide angle lens will give less accuracy.
  • Another method to increase precision is the use of a video camera with more pixels. This method can also be used to drive the machine 8 through a curve with a constant turning radius. Then the machine 8 is steered in such a way that the correlation peak is shifted a certain number of pixels at every correlation measurement.
  • Another method to help the driver of the machine 8 with the steering of the same is to paint a line on the ground or tightening a string that the machine 8 automatically can follow.
  • the line or the string should have as large contrast over the surface layer as possible.
  • the processing unit is, in this case, looking for the string or the line in every analyzed image and the number of pixels it has been shifted sideways is a measure of the machine's 8 deviation from the correct course. This number of pixels is then used to steer the machine 8, via the steering servo, back on course.
  • This method works both for automatic steering straight ahead and for automatic steering through a curve. Also this steering can be made arbitrarily accurate by choice of lens and the number of pixels in the camera.
  • An appropriately chosen filter in front of the lens can help to increase the contrast between the line or string and the background and thus make them easier to be detected in the video signal.
  • Figure 1 shows a flow chart of a MTT method for placing at least one duct/cable 2/3 below a hard surface layer LI in an area comprising the steps of:
  • Figure 3a and 3b schematically shows a cross section of an area in which ducts 2 are placed in a micro trench 1.
  • the area in figure 3 a and 3b is a three dimensional region of a typical area comprising a first layer LI being a hard surface layer such as asphalt or concrete, and a second layer L2 being a bearing layer for the first layer LI and usually consisting of sand, gravel, and stones.
  • the second layer L2 is naturally located below the first layer LI as shown in figure 3a and 3b.
  • the sawing step involves: sawing the micro trench 1 through the first layer LI into the second layer L2, which means that the micro trench 1 is sawn as shown in figure 3a and 3b.
  • the micro trench 1 is sawn so deep that at the least one duct/cable 2/3 is placed in the micro trench 1 below the first layer LI (i.e. all installed ducts/cables 2/3 are placed below the first layer LI).
  • all ducts 2 and cables 3 for fibre optic networks can be placed deep enough so that they are safe if the surface layer LI is removed and/or replaced, e.g. when repairing the road.
  • the duct 2 is a duct arranged to hold "air-blown fibre” (so called EPFU) or fibre cables.
  • the duct/s 2 and/or the communication cable/s 3 are placed in the micro trench 1 so that they are entirely positioned below the first layer LI.
  • the micro trench 1 is filled with a suitable filling material 6 so that the area can be restored.
  • the filling material 6 may be sand or any other material with suitable properties.
  • a filling material 6 that is liquid at the time of the filling and which later cures and becomes highly resistant against compression forces is a preferred filing material.
  • the micro trench 1 is filled with the filling material 6 to a suitable level, and if needed the filling material 6 is thereafter packed with a compactor that fits the width w of the micro trench 1.
  • the micro trench 1 is sealed using a sealing material, such as bitumen, in order to get a water tight sealing.
  • a sealing material such as bitumen
  • patching may also be made with cold asphalt which is a simple and cheap method of restoration. A suitable amount of cold asphalt is simply poured and scraped into the micro trench 1, and thereafter compacted to a smooth and hard surface. Any excess asphalt can then be collected and removed.
  • Figure 4 shows the above described embodiment.
  • the surface 4 and the bottom 5 of the first layer LI are indicated in figure 4.
  • hot bitumen or bitumen mix when sealing the micro trench 1.
  • other material such as concrete or polymer modified bitumen will work.
  • the first sealing S 1 is put down to seal the micro trench 1 substantially flush with the bottom 5 of the first layer LI so that the micro trench 1 can be cleaned with a high-pressure washer to remove any residue of sand from the asphalt/concrete edges.
  • the micro trench 1 may be dried and pre -heated using a propane burner and finally, the micro trench 1 is filled flush with the top surface 4 of the first layer LI using a suitable sealant such as a hot crack sealant based on bitumen.
  • the micro trench 1 is cut with a disc cutter/sawing machine 8 having a diamond coated saw blade 14.
  • Such a diamond coated saw blade 14 can easily saw through even the hardest materials, such as stone or concrete, and has proved very useful in the present application since the sides of the micro trench 1 becomes exceptionally straight, clean and easy to restore.
  • Prior art methods to cut micro trenches such as using a blade with tungsten carbide teeth, creates cracks in the edges of the micro trench that will make complete sealing afterwards much harder and more expensive compared the present method.
  • the micro trench 1 is preferably cut/sawed with a modified so-called road-saw 8 (sawing machine 8) having a diamond coated saw blade 14.
  • road-saw 8 sawing machine 8
  • diamond coated saw blade 14 the inventors have realized that one or more of the following improvements are useful and should be considered as embodiments:
  • these guiding means 17 should be arranged so that the outlets 12 from the stabilizing device 13 are placed on top of each other in such a way that the order of the ducts/cables 2/3 from the inlet 11 into the stabilizing device 13 and out into the micro trench 1 is preserved;
  • ⁇ Servo controlled by a sensor to automatically keep the saw blade 14 vertical on uneven surfaces. (E.g. when the drive train (wheels or caterpillar tracks) on one side are on the sidewalk and the drive train on the other side are on the road.)
  • An arrangement consisting of a temperature sensor 40, for example of the infrared type, sensing the temperature of the saw blade 14 and being connected to a control device 39.
  • the output from the control device 39 is connected to a feeding device 36, feeding a cooling medium to nozzle(s) on the stabilizing device 13 and/or to nozzles inside the protective cover over the saw blade 14.
  • the control device 39 is arranged by means of the feeding device 36 to automatically provide more cooling medium to the nozzle(s) when the temperature of the saw blade 14 increases and vice versa.
  • Cooling medium may be cooling water or cooling air.
  • the saw blade 14 is composed of a number of sawing disks separated by slits blades 34, 35, the water may be applied through the drive shaft.
  • the feeding device 36 is also connected to the channel for cooling water through the drive shaft so that the cooling water can reach all blades 32, 33.
  • An alternative or complement to adding more cooling medium through nozzles or drive shaft may be to lower the rotation speed of the saw blade 14 when its temperature increases and vice versa.
  • Figure 8 shows an embodiment using a sawing machine 8 comprising a saw blade 14 arranged for up-cut. Up-cut is defined as the rotating direction of the saw blade 14 in relation to the sawing direction 9 as shown by figure 8. All known sawing machines have the opposite rotating direction. By changing the rotating direction of the sawing machine 8 to up-cut helps to remove the cut material from the micro trench 1, thereby providing a "clean" micro trench 1.
  • the sawing machine 8 comprises a stabilizing device 13 arranged immediately behind the saw blade 14, wherein the stabilizing device 13 has at least one guiding means 17, such as channels, for guiding ducts/cables 2/3 when placed in the micro trench 1 immediately behind the saw blade 14. If a plurality of ducts/cables 2/3 is placed at the same time, the stabilizing device 13 is arranged to be able to place the ducts/cables 2/3 in preserved order. This may be achieved by having individual channels for the ducts/cables 2/3 in the stabilizing device 13 so that the order of the ducts/cables 2/3 will be maintained through the stabilizing device 13.
  • the stabilizing device 13 has at least one guiding means 17, such as channels, for guiding ducts/cables 2/3 when placed in the micro trench 1 immediately behind the saw blade 14. If a plurality of ducts/cables 2/3 is placed at the same time, the stabilizing device 13 is arranged to be able to place the ducts/cables 2/3 in
  • the depth d of the micro trench 1 should be larger than the depth of the first layer dl together with the height d2 of at least one duct 2 or at least one communication cable 3, i.e. d > dl + d2 which means that the depth d of the micro trench 1 is larger than the height of the first layer dl plus the combined height of one or more ducts 2 and/or communication cables 3.
  • the above mentioned relation holds.
  • the micro trench 1 should not be deeper than necessary.
  • Normal depth d of the micro trench 1 can be around 400 mm, and unlike the width w of the micro trench 1, the depth d can often be adjusted continuously during operation. The sawing depth can therefore be reduced gradually as the number of ducts/cables 2/3 laid in the micro trench 1 is reduced.
  • micro trench 1 should not be wider than necessary, since a wider micro trench 1 is more expensive than a narrow micro trench 1.
  • a narrower micro trench 1 can make it more difficult to install the ducts/cables 2/3, so there is an optimal width of the micro trench 1, since e.g. if the micro trench 1 is too narrow, all ducts/cables 2/3 will be piled on top of each other so that the depth of the top duct/cable 2/3 will be too shallow.
  • suitable dimensions for a micro trench 1 should have a depth d between 200 - 500 mm (and preferably 300 - 500 mm) and a width w between 10 - 30 mm (and preferably 15 - 25 mm) according to an embodiment for installation efficiency and low cost. Further, with these dimensions minimum disruption of traffic is possible since traffic can pass over an open micro trench 1.
  • the method for placing at least one duct/cable 2/3 comprises the steps of:
  • the steps of scanning and identifying are performed before the other steps in the method according to this embodiment.
  • the area is scanned by means of a ground penetrating radar device, such as a GEO-radar or any other suitable equipment.
  • the scanning and identifying steps means that when performing the subsequent sawing step it may be avoided to accidentally cut/damage obstacles in the area which may result in delay and extra cost in the micro trenching process.
  • After sawing a micro trench 1 in the scanned area at least one duct 2 and/or a communication cable 3 is placed in the micro trench 1.
  • the micro trench 1 is filled with a suitable filling material 6 so that the road surface can be restored.
  • the method may also involve the step of: installing or blowing fibre or fibre optic cable in one or more ducts 2 if ducts were placed in the micro trench 1.
  • the method described above also may comprise the step of: making one or more branching points connected to the micro trench 1.
  • the branching points may be made by means of a diamond coated core drill or a hand-held sawing machine with a diamond coated sawing chain or disc.
  • the method may also comprise the further step of: boring one or more channels from the branching points to one or more houses using controlled or guided boring. It is important that channels are bored below the first layer LI in the second bearing layer L2. Ducts/cables 2/3 are thereafter installed in these channels when the drill is pulled back.
  • Figure 5 shows a typical logical structure of a Fibre To The Home (FTTH) network in a residential area, where "D" is a distribution node and "F” is a splicing point where larger fibre cables are spliced to smaller ones (or in case of a PON network (Passive Optical Network) where optical splitters are placed).
  • the network between a distribution node D and a splicing point F is called distribution network and the network between the splicing point F and the individual homes is called access network.
  • Both the ducts/cables 2/3 for the distribution network and for the access network can be installed using the present method.
  • a residential area being constructed with FTTH is normally divided into a number of smaller residential subareas. Somewhere in the residential area or outside of the residential area there must be a site where optical panels and electronics needed to form a so-called distribution node D are housed.
  • the distribution node D can be housed in an existing building or be built in a small dedicated building or in a large ground cabinet. Each distribution node D may contain electronics and optical panels for anywhere between a few hundred households up to several thousand households.
  • the size of the area to be built from a single distribution node D can be adjusted within wide limits and depends primarily on practical considerations, such as space in the distribution node D, difficulties with management of a large number of smaller distribution nodes D, etc. This concept can also be adapted for any number of fibres per household.
  • the distribution node D contains the other end of all optical fibres that originate from each household in the residential area. If e.g. a residential area with 500 households is being equipped with 2 fibres per household, there will be 1000 incoming fibres to the distribution node D.
  • the distribution node D should preferably have a central location in the area being built as shown in figure 5.
  • the fibre structure of a point-to-multipoint-network or a so-called Passive Optical Network (PON) is more or less the same.
  • the difference being that the number of incoming fibres to the distribution node D in this case equals the number of households divided by a factor (e.g. 8, 16, 32, etc. depending on the chosen type of the so called splitter).
  • a factor e.g. 8, 16, 32, etc. depending on the chosen type of the so called splitter.
  • distribution cables extend out to splicing points F in manholes or ground cabinets.
  • Distribution cables are normally designed for the number of households in the area plus 10 % spare so that in the future, newly built buildings easily can be added to the network.
  • a splicing point covers an area with 22 houses and the requirement is two fibres per house, then 48 fibres from the distribution cable are needed.
  • Fibres from the distribution cables are spliced in the splicing points F to fibres from the access cables. These access cables then extend to each one of the houses being connected.
  • the splicing point F should be placed centrally in each residential subarea, with e.g. around 22 houses.
  • the splicing point F can be physically realised in a street cabinet or in a manhole by the roadside.
  • typically 10-12 ducts 2 extend from the ground cabinet or manhole each way along the road.
  • Each of these ducts 2 then extends into each of the houses.
  • access cables are blown into each of these ducts 2.
  • a micro trench 7 is sawed in the roadside on both sides of the road and houses are connected to the closest micro trench 7, or a micro trench 7 is sawed on only one side of the road or in the middle of the road and houses on both sides are connected to this single micro trench 7.
  • branching micro trenches are made to a boundary between two properties (houses) on the opposite side of the road according to an embodiment. Then a duct/channeling tube 2 is placed in the branching micro trench to each one of the two properties. In this way, a micro trench across the road need only be made for every second property on the opposite side of the road. Micro trenching across the road for every second property is a cheap and cost effective method. Branching off a main trench 7
  • Branching off from a main micro trench 7 can be carried out in a number of ways.
  • the branches may be sawn either before as shown in figure 6 or after the main trench 7 is sawn. In order to obtain a large radius curve for the ducts/tubing 2, both methods are best done at about a 45° angle from the main micro trench 7.
  • the branches may cross the location of the main micro trench 7 or go "flush" with the main trench 7. When the main micro trench 7 is sawed and the ducts/channeling tubes 2 are laid it is easy to one by one route one of the uppermost ducts through each of the sawed branches up to each residence, as shown in figure 10 and to the right in figure 6.
  • An alternative method of branching is to first bore a hole at each branching point with a suitably sized core drill.
  • the main micro trench 7 can then be sawed along all these holes in the same manner as described above as shown in figure 7.
  • This method is suited both to making the house connections with a branching micro trench sawn in the way described above as well as making house connections with controlled/guided boring.
  • An alternative method of branching is to first make a hole at each branching point.
  • the holes may be made using a suitably sized core drill (for a round hole) or using a hand tool with a diamond saw blade or chain (for a rectangular hole).
  • the main micro trench 7 can then be sawn along all these holes in the same manner as described above and as shown in figure 7.
  • This method is suited both to making the house connections with a branching micro trench sawn in the way described above as well as making house connections with controlled boring. Controlled boring is sometimes preferred for making the house connections, because it avoids (e.g. goes under) obstacles like fences, hedges, trees, etc. However, another piece of expensive machinery (core drill) is needed at the installation site.

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Abstract

La présente invention concerne une machine (8) agencée pour scier des micro-tranchées (1) et placer des conduits/câbles (2/3) dans des micro-tranchées (1), ladite machine (8) comprenant : - une lame de scie (14) agencée pour scier une micro-tranchée (1) dans une zone à travers une première couche (L1) et dans une seconde couche (L2), ladite première couche (L1) étant une couche de surface dure et ladite seconde couche (L2) étant une couche de support de ladite première couche (L1) et étant positionnée au-dessous de ladite première couche (L1) ; et un dispositif de stabilisation (13) agencé pour stabiliser les côtés de ladite micro-tranchée (1) lors de la mise en place desdits conduits/câbles (2, 3) dans ladite micro-tranchée (1) complètement au-dessous de ladite première couche (L1) par le biais d'un moyen de guidage (17), une partie avant (18) dudit dispositif de stabilisation (13), lors de la mise en place desdits conduits/câbles (2, 3) dans ladite micro-tranchée (1), étant positionnée immédiatement derrière ladite lame de scie (14) et possédant une forme qui est principalement complémentaire à la forme de ladite lame de scie (14), et ledit dispositif de stabilisation (13) comprenant en outre une ou plusieurs buses (31) agencées pour refroidir ladite lame de scie (14).
PCT/SE2017/050916 2016-09-23 2017-09-21 Machine d'installation de conduits/câbles dans des micro-tranchées WO2018056889A1 (fr)

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