GB1572253A

GB1572253A - Excavating head

Info

Publication number: GB1572253A
Application number: GB2661179A
Authority: GB
Original assignee: Komatsu Ltd
Current assignee: Komatsu Ltd
Priority date: 1977-01-06
Filing date: 1977-01-06
Publication date: 1980-07-30

Description

(54) AN EXCAVATING HEAD (71) We, KABUSHIKI KAISHA KOMATSU SEISAKUSHO a Corporation organised under the laws of Japan of 3-6, 2-chome, Akasaka, Minato-ku, Tokyo, Japan, do hereby declare the invention for which we pray that a Patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement:- This invention relates to an excavating head for use in laying a pipeline underground, especiaily a pipeline of a comparatively small diameter for gas and water supply and sewerage systems and cables etc.

There has heretofore been employed the "Open Cut Method" for laying a pipeline underground which comprises the steps of excavating a continuous trench at a predetermined depth in the ground, laying pipeline to be laid underground on the bottom of the trench connecting them transversely, placing wooden slippers under the pipeline at a reference height set by stretching a string, fixedly securing the pipeline and the slippers by means of concrete blocks, and then filling back the excavated trench.This method is, however, disadvantageous in that it encounters various problems caused by such things as traffic, buildings, etc. in cities and suburbs, legal restrictions for working area, hindrances such as pipelines already laid, and the necessity of destruction of completed roadbeds etc., and therefore a considerably high construction cost and a long period of construction are inevitably required.

To eliminate such disadvantages, a method of laying a pipeline of comparatively small diameter underground by propelling them directly in the earth has been developed and employed as an alternative to the open cut method.

Conventional methods of laying pipelines underground in this way may be broadly divided into three: namely, a method in which a pilot head is used as a guide unit so that a pipeline led by the pilot head may be pushed and propelled in the earth so as to consolidate the earth and sand through which the pipeline passes thereby laying the pipeline underground; a method in which a pilot head having a propelling function is used as a guide unit so that the pipeline led by the pilot head may be pushed and propelled in the earth so as to consolidate the earth and sand thereby laying the pipeline underground; and a method in which the earth and sand are excavated while the pipeline to be buried is directly pushed and propelled, and the excavated earth and sand are discharged through the pipeline towards the launching pit.

The first method is disadvantageous in that the straight drive or advance of a long pipeline depends on or is impaired by the configuration of the solid pilot head, changes in density of the earth and sand to be consolidated and pebbles scattered in the earth.

The method disclosed in the Japanese Patent Publication No. 19767/1974 in which a pilot head having a propelling function is employed is also disadvantageous in that the control of the direction of propulsion of the pilot head is difficult because the propelling function is limited only to straight drive or advance.

This method has a big advantage in that the propulsion resistance can be reduced substantially, but it has big disadvantages in that the direction of movement of the pilot head is largely influenced by changes in earth stratum and existence of pebbles, and therefore it may sometimes get out of the predetermined depth and raise the ground or get out of the predetermined course and damage pipelines already laid underground. For this reason, this method could not be applied in the past to sewerage system etc. which are required to be installed at a predetermined gradient and with high accuracy in the vertical plane because it is necessary to allow sewerage to flow by gravity in the systems.

Further, the latter method is disadvantageous in that the movement of the earth and sand within the pipeline to be laid underground renders the measurement and control of the direction of advance of the pilot head difficult, and the number of treatment steps is increased due to the necessity of discharging the excavated earth and sand and underground water towards the launching pit. Therefore, provision of a launching pit having a large area or space is unavoidable, and also the operation is required to be effected under extremely unfavourable conditions.

According to the present invention there is provided an excavating head comprising a casing, an hydraulic motor accommodated within the casing, a screw conveyor driving shaft adapted to be driven by the hydraulic motor, a gear means engageable with said screw conveyor driving shaft, and a cutter driving shaft adapted to be driven by the gear means, said cutter driving shaft having a cutter means mounted thereon, and said screw conveyor driving shaft having an earth conveyor means mounted thereon.

The invention is hereinafter more particularly described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a side elevational view showing a system in which the pilot pipeline is employed for discharging excavated earth, and the pipeline of a larger diameter led by an excavating head is laid underground by the action of the excavating head, Figure 2 is a longitudinal sectional view of one embodiment of excavating head, Figure 3 is an enlarged view of the leading end of the excavating head shown in Figure 2, Figure 4 is a sectional view taken along line XXIV-XXIV in Figure 3, Figure 5 is a sectional view of another embodiment of the excavating head, and Figure 6 is a sectional view taken along line XXVI-XXVI in Figure 5.

The present invention will now be described below by way of examples only with reference to the accompanying drawings.

Figure 1 illustrates an example in which the excavating head 143 is employed. In this example, the guide pipeline 2 which is already laid underground is used as a guide when excavating a hole of a large diameter underground, and the arrangement is made in such a way that the removed earth 145 is carried into the receiving pit 5 by means of the screw conveyor 144 which extends inside the guide pipeline 2 and is adapted to be driven by the aforementioned excavating head. Connected to the excavating head 143 is the hose 122 which extends into the pipeline 121 to be laid underground following the excavating head and which is connected to a fluid supply source by way of the connector 123 so as to drive the excavating head.The propelling jack 3 is adapted to be operated depending on the amount of excavation made by excavating head 143 so that the guide pipeline 2, the screw conveyor 144 and the excavating head 143 may be recovered in the receiving pit 5. The propelling jack 3 completes its propulsion when the leading end of the pipeline 2 to be laid underground reaches inside the receiving pit 5. The screw conveyor 144 has a length nearly equal to that of the guide pineline, and its intermediate connections can be attached and detached easily by means of couplers.

Figure 2 shows the internal structure of excavating head 143. The excavating head comprises a casing 146 adapted to be divided into a plurality of sections, a hydraulic motor 149 mounted within the casing and being adapted to be driven by fluid under pressure supplied by hose 147 and discharged through hose 148, said hydraulic motor having an output shaft 150 which is engaged with a coupling 151, a conveyor or driving shaft 152 which is engaged with the coupling and is adapted to directly transmit the rotation of hydraulic motor 149 to screw conveyor 153. The coupling 151 has a gear 154 fitted thereto which is engaged with a gear 155. The gear 155 is adapted to drive through a shaft 156 fixedly secured thereto a gear 157. The gear 157 is engaged in turn with ring gear 158.

The ring gear 158 is coupled with a cutter driving shaft 159. The cutter means 161 is adapted to be rotated in the direction reverse to the direction of rotation of the screw conveyor through a cylindrical bearing and a thrust bearing mounted between the casing 146 and housing 160.

The housing 160 is fixedly secured to partition 162 which carries the conveyor shaft 152 rotatably. Further, the excavating head 143 has at its front end a guide tube 163 for connecting thereto the guide pipeline 2. The guide tube 163 has an inlet port 164 through which the earth and sand excavated by cutter 161 is directed towards the screw conveyor 153 and the guide pipeline connecting portion 165.

Connected to the front of the thus constructed excavating head 143 are the guide pipeline 2, and the screw conveyor 144 accommodated within the latter, and also connected to the rear of the excavating head 143 and the pipeline 121 to be laid underground. Using the guide pipeline 2 as a guide, the propelling jack 3 is propelled in response to the progress of excavation of the excavating head 143 so as to lay the pipeline 121 underground.

Figure 3 shows the detailed structure of a cutter means 161. The cutter means 161 is connected to the cutter driving shaft 159 by means of a bracket 167. The cutter means 161 is of a trapezoidal shape in side elevation and has an inclined surface to which are fitted a plurality of cutter blades 166. The earth and sand excavated by the rotation of the cutter means 161 drops through the inlet port 164 into the conveyor chamber 168 and is then sent by the screw conveyor 153 into leading pipeline 2.

Figure 5 shows a further example having an enlarged earth and sand accommodating chamber 171 in the cutter means 161 so as to make the inlet port 164 of the guide tube 163 larger and also having a scraper 170 mounted in the outer periphery of the inlet port so as to ensure efficient feeding of the excavated earth and sand into conveyor chamber 168.

Figure 6 shows a section taken along XXVI-XXVI in Figure 5 for the purpose of explaining the relationship between the scraper 170 and the inlet port 164 for excavated earth and sand.

The excavating head described and claimed herein is used in a method of laying pipes underground which forms the subject of our co-pending application No.

290/77 Serial No. 1 572252 to which attention is directed.

WHAT WE CLAIM IS: 1. An excavating head comprising a casing, an hydraulic motor accommodated within the casing, a screw conveyor driving shaft adapted to be driven by the hydraulic motor, a gear means engageable with said screw conveyor driving shaft, and a cutter driving shaft adapted to be driven by the gear means, said cutter driving shaft having cutter means mounted thereon, and said screw conveyor driving shaft having an earth conveyor means mounted thereon.

2. An excavating head as claimed in claim 1, wherein said head comprises bearing means within the housing for surrounding the conveyor driving shaft directly connected to the motor shaft, and the cutter driving shaft which surrounds said housing has a freely rotatable bearing means between said casing and said housing so that the cutter driving shaft may be rotated in the direction reverse to that of the conveyor driving shaft.

3. An excavating head as claimed in claim 1, wherein said cutter means comprises a cutter body of a trapezoidal shape in section having a plurality of cutter blades mounted thereon, said cutter means being adapted to be rotated around the outer periphery of the guide pipeline connecting portion, said guide pipeline connecting portion having an inlet port through which the earth and sand is introduced in a conveyor chamber so that the earth and sand may be discharged by a conveyor means.

4. An excavating head as claimed in claim 1, wherein said cutter means has a chamber for accommodating the excavated earth and sand, and a scraper located in the vicinity of the earth and sand inlet port of the guide pipeline connecting portion for scraping together the earth and sand within said chamber.

5. An excavating head substantially as herein described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

head 143 and the pipeline 121 to be laid underground. Using the guide pipeline 2 as a guide, the propelling jack 3 is propelled in response to the progress of excavation of the excavating head 143 so as to lay the pipeline 121 underground.

Figure 3 shows the detailed structure of a cutter means 161. The cutter means 161 is connected to the cutter driving shaft 159 by means of a bracket 167. The cutter means 161 is of a trapezoidal shape in side elevation and has an inclined surface to which are fitted a plurality of cutter blades 166. The earth and sand excavated by the rotation of the cutter means 161 drops through the inlet port 164 into the conveyor chamber 168 and is then sent by the screw conveyor 153 into leading pipeline 2.

Figure 5 shows a further example having an enlarged earth and sand accommodating chamber 171 in the cutter means 161 so as to make the inlet port 164 of the guide tube 163 larger and also having a scraper 170 mounted in the outer periphery of the inlet port so as to ensure efficient feeding of the excavated earth and sand into conveyor chamber 168.

Figure 6 shows a section taken along XXVI-XXVI in Figure 5 for the purpose of explaining the relationship between the scraper 170 and the inlet port 164 for excavated earth and sand.

The excavating head described and claimed herein is used in a method of laying pipes underground which forms the subject of our co-pending application No.

290/77 Serial No. 1 572252 to which attention is directed.

WHAT WE CLAIM IS: 1. An excavating head comprising a casing, an hydraulic motor accommodated within the casing, a screw conveyor driving shaft adapted to be driven by the hydraulic motor, a gear means engageable with said screw conveyor driving shaft, and a cutter driving shaft adapted to be driven by the gear means, said cutter driving shaft having cutter means mounted thereon, and said screw conveyor driving shaft having an earth conveyor means mounted thereon.
2. An excavating head as claimed in claim 1, wherein said head comprises bearing means within the housing for surrounding the conveyor driving shaft directly connected to the motor shaft, and the cutter driving shaft which surrounds said housing has a freely rotatable bearing means between said casing and said housing so that the cutter driving shaft may be rotated in the direction reverse to that of the conveyor driving shaft.
3. An excavating head as claimed in claim 1, wherein said cutter means comprises a cutter body of a trapezoidal shape in section having a plurality of cutter blades mounted thereon, said cutter means being adapted to be rotated around the outer periphery of the guide pipeline connecting portion, said guide pipeline connecting portion having an inlet port through which the earth and sand is introduced in a conveyor chamber so that the earth and sand may be discharged by a conveyor means.
4. An excavating head as claimed in claim 1, wherein said cutter means has a chamber for accommodating the excavated earth and sand, and a scraper located in the vicinity of the earth and sand inlet port of the guide pipeline connecting portion for scraping together the earth and sand within said chamber.
5. An excavating head substantially as herein described with reference to and as illustrated in the accompanying drawings.