Field of the invention

The present invention relates to an apparatus in the field of ground heavy machinery and tunnel digging/drilling. More specifically the present invention relate to an apparatus and a method of for picking up metal mesh mats and placing metal mesh mats on the walls of tunnels for coating and support.

Background of the invention Metal reinforcing mats such as steel mats have been used for a long time for support in construction such as buildings, roadways and tunnels etc. The reinforcing mats are metal mesh mats made of spaced longitudinal parallel metal rods and perpendicular disposed connecting rods forming a net of meshes. The reinforcing mats are heavy and difficult to handle. Mounting of such mats usually requires heavy duty machinery and considerable manpower.

Several methods have been used for placing metal mesh mats on the walls of tunnels during construction. The most common method is purely manual where a number of workers pick up each mat and place it onto the tunnel wall where each mat can be transported in the tunnel by a fork lift or carried by a number of men to the correct location before placement. This method requires a number of men to form each mat to the shape of the tunnel wall and place it in the right place and mount it onto the tunnel wall.

Another method uses manual force to pick up the mat and place each mat onto a mould, which is mounted on a crane device. The mould gives the mat a curved shape and the crane places the mat in the right place on the tunnel wall, where the workers attach the mat to the tunnel wall and thereafter detach the mat from the mould by manual labour.

These methods require a number of workers using their physical strength for the major part of the work. There is therefore a need for an automated and mechanical method and device for decreasing the manual labour and physical effort to pick up metal mesh mats and placing them on tunnel walls.

Means for handling reinforcing mats have been designed. US 3,180,671 discloses a lifting device suspendible from a lifting device, such as a crane, having a plurality of gripping devices to grip a predetermined number of reinforcing mats from a pile of mats. Summary of the invention

The present invention provides a new apparatus and a method for picking up metal mesh mats and placing them onto the tunnel walls for coating and support during construction of tunnels. The apparatus and a method provide a solution to decrease manual labour and increase productivity and efficiency of laying metal mesh mats to the tunnel walls during construction of tunnels.

The object of the invention is obtained by providing an apparatus with two different properties. Firstly, the apparatus comprises a novel gripping device which grips the top mat from a pile of mats and leaves the second mat in the pile behind. This is obtained by forming the hooks of the gripping means to pass between the mats when the gripping means is engaged and holding the map locked to the gripping means until released. Secondly the apparatus comprises a forming device for bending the mat to fit the surface onto which it is being mounted. The bending means comprises a telescopic boom for giving the mat a curve shape before placing it onto the tunnel wall, but walls of most tunnels are often curve shaped. The apparatus consists of a frame structure having two arm structures and mans for connecting the apparatus to a crane or a boom of construction equipment. The arm structures are equipped with a plurality of gripper units to grip and lift one metal mesh mat from a pile of mats and hold against a tunnel wall while the mat is being mounted on a tunnel wall. In a first aspect an apparatus is provided for mounting metal mesh mats onto the tunnel walls. The apparatus comprises a support base 3, connection means for connecting the support base of the apparatus to construction equipment or heavy machinery and two arm members connected to the support base. The arm members have gripping means to grip opposite sides of the top metal mesh mat at the corners of the top metal mesh mat. The apparatus is characterised in that it further comprises a centrally placed vertical beam with adjustable length extending from the support base and a crossbar attached to the lower end of the centrally placed vertical beam.

In a second aspect a method is provided for mounting metal mesh mats onto the tunnel walls. The method comprises gripping a metal mesh mat using an apparatus for mounting metal mesh mats onto the tunnel walls, where the apparatus comprising a support base, connection means for connecting the support base of the apparatus to construction equipment or heavy machinery, two arm members connected to the support base with gripping means to grip opposite sides of the metal mesh mat at the corners of the metal mesh mat, a centrally placed vertical beam with adjustable length extending from the support base, a pair of guiding strips connecting a pair of gripping means along the length of the metal mesh mat to be mounted, and a crossbar connecting the guiding strips, where the crossbar is attached to the lower end of the centrally placed vertical beam. The method further comprises the steps of lifting one metal mesh mat from a pile of mats by means of the construction equipment or heavy machinery, bending the metal mesh mat by pushing down the centrally placed vertical beam with or without pushing down the crossbar, and placing the metal mesh mat up against a tunnel wall and holding it in place while it is being mounted onto the tunnel wall.

In a third aspect an apparatus is provided for mounting metal mesh mats onto the tunnel walls. The apparatus comprises a support base 3, connection means for connecting the support base of the apparatus to construction equipment or heavy machinery and two arm members connected to the support base. The arm members have gripping means to grip opposite sides of the top metal mesh mat at the corners of the top metal mesh mat. The apparatus is characterised in that it further comprises a pair of guiding strips, connecting a pair of gripping means along the length of the metal mesh mat to be mounted, a centrally placed vertical beam with adjustable length extending from the support base and a crossbar connecting the guiding strips. The crossbar is attached to the lower end of the centrally placed vertical beam.

Description of the invention

The present invention provides a solution for picking up metal mesh mats, for coating tunnel walls, from a pile of mats. The apparatus is mounted onto a construction equipment such as a fork lift or a crane device having an arm to lifting the mat from the pile and holding it against the tunnel wall while it is mounted to the wall. The apparatus comprises a connection member for connecting the apparatus to the construction equipment. The connection means is attached to a support base, which connects to two arm structures extending outwardly from the support base towards both corners of each end of the mat. The far end of the arm structure has gripping means on each side to grip each corner of the mat on that end of the metal mesh mat. The gripping means of the apparatus is designed to pick only the top mat from a pile of mats up and leaving second mat in the pile behind. This is obtained by means of a hooking member which is operated by a first jack and a sliding member operated by a second jack. The hooking member and the sliding member are connected. The hook itself of the hooking "member" is elongated and the tip of the hook is the only part of the hook which reaches below the surface of the gripping means that faces the metal mesh mat. The sliding member pushes the hook along the surface of the metal mesh mat. A sensor detects when the hook makes contact with a pin in the mat and the jack pushing the sliding member stops and the jack activating the hook member is activated to lock the hook around the pin. This is clearly shown in fig. 4.

In addition to be able to grip only one mat from a pile of mats, the apparatus can also bend the mat in the middle along the x- or the y-axis. This forming or bending feature allows the mat to fit the surface onto which it is being mounted which is usually a partially curved shaped tunnel wall. A centrally placed vertical beam with adjustable length extends from the support base in a central direction between the four gripping means. In addition to that a crossbar is attached to the centrally placed vertical beam centrally between the two arm structures. The crossbar is attached to the lower end of the centrally placed vertical beam and extends from side to side. The centrally placed vertical beam can be a telescopic boom which can be extended alone below the crossbar or, if it attached to the crossbar, pushes the crossbar downwards. If the boom is extended alone it bends the metal mesh mat along the length of the mat and if it pushes the crossbar down it bends the mat along the width of the mat. The two arm structures may be connected by a pair of guiding strips/runners connecting parallel a pair of gripping means on each arm structure along the length of the metal mesh mat. The guiding strips/runners are made of flexible material such as plastic or rubber and assist in placing the arms correctly on the top mat in the pile of mats before the hooks are engaged to attach the mat to the device. In the case where the two arm structures may be connected by a pair of guiding strips/runners the crossbar centrally connects the guiding strips/runners. The embodiment of the invention shown in the drawings shows the apparatus including the guiding strips/runners, but as stated above the guiding strips/runners are not required to pick up the mat, bend it and hold it against the tunnel wall during mounting. In the present context the term "metal mesh mat" refers to a reinforcing mat used for constructions of any kind. The typical metal mesh mat is made from metal rods, where spaced longitudinal parallel metal rods and perpendicular disposed connecting rods form a net mat with a plurality of meshes.

In the present context the term "support base" refers to the top part of a frame which is attached to the connection means. The connection means provides a physical and control connection to the arm of a crane or such an equipment. The support base is also connected to the arm structures of the frame through hinges. Therefore the term "frame includes the support base, hinges and arm structures, which connect to the telescopic boom through the support base and the gripping means through the arm

members/structures. In the present context the term "guiding strips/runners" refers to longitudinal members made from flexible material connecting the arm members on each side. This is shown clearly in fig. 2. The guiding strips/runners are not essential for the apparatus to work and are therefore not a part of the frame. The however give support to the mat as it is being handled and connect the crossbar as it extends centrally from the telescopic boom. The guiding strips/runners further assist in bending the mat when it is being formed to fit the tunnel wall.

In an embodiment of the present invention a pair of guiding strips connect a pair of gripping means along the length of the metal mesh mat to be mounted. In an embodiment of the present invention each gripping means further comprises a sliding member and a hooking member, where the sliding member and the hooking member are connected, but their movement is driven by separate jacks.

In an embodiment of the present invention the centrally placed vertical beam is a telescopic boom. In an embodiment of the present invention each arm structure has an adjustment means for setting the distance between the gripping means for accurately placing the gripping means in the corner of the mat before gripping the shorter edge of the metal mesh mat.

In an embodiment of the present invention the gripping part of the method comprises positioning the arms structures at opposite ends of the metal mesh mat, activating the gripping means to grip each corner of the mat and moving the sliding member and thereby the hooking member along the surface of the mat such that when the hooking member comes in contact with a metal pin in the mat. The jack operating the hooking member is activated to lock the hooking member around the metal pin.

Detailed description of the invention

The invention will now be described in relation to the drawings.

Figure 1 is a schematic drawing showing the principle of the invention where the apparatus of the present invention is used to mount a metal mesh mat 1 onto a tunnel wall 2. Fig. 1A shows the apparatus picking up a metal mesh mat 1 from a pile of mats lb, where the bending means of the apparatus is in a neutral/gripping position. Fig. IB shows the apparatus having picked up a mat and bent it using the bending/forming means to give the mat a curved shape matching the shape of the tunnel wall. The apparatus comprises support base 3 attached to a connection means 4 for connecting the apparatus to construction equipment or heavy machinery 5. The apparatus has two arm structures 6 connected by hinges to the support base 3 and gripping means 7 at the end of the arm structures to grip the metal mesh mat 1. The apparatus further comprises guiding strips (not shown in this drawing) to assist with placing the arm structures 6 correctly on the top mat 1 in the pile of mats lb before the gripping means (not shown in this drawing) is engaged to attach the mat 1 to the device. The figure further shows bending means 9, 10 for bending the metal mesh mat 1 and thereby giving the mat the form of a curve-shaped tunnel wall 2.

Figure 2 shows a side view (A) perspective view (B) and a front view (C) of the apparatus of the present invention. A support base 3 links two movable arm structures 6 connected to the support base 3 by hinges. Each arm structure 6 has gripping means 7 to grip the metal mesh mat 1 in the corners of the metal mesh mat 1. The apparatus has a connection means 4 for connecting the apparatus to construction equipment or heavy machinery 5 the support base 3. This connection means 4 is a coupler or a linker providing the device with electric or hydraulic power to move the gripping means 7 and other movable components of the device. The apparatus is designed to form or bend the metal mesh mat 1 before it is placed up against a tunnel wall 2 for mounting. The forming or bending is facilitated by a centrally placed vertical beam or telescopic boom 9 with adjustable length. The telescopic boom 9 extends vertically from the support base 3. A pair of guiding strips/runners 8 connects two gripping means along the length of the metal mesh mat 1 to be mounted on each side. The guiding strips/runners 8 are made from flexible material such as plastic. Finally, a crossbar 10 connects the guiding strips/runners and the telescopic boom 9.

Figure 3 outlines the individual components of the gripping means 7. Each gripping is made of one hooking member 11 and one sliding member 12. The sliding member 12 and the hooking member 11 are connected (not shown in this drawing), but their movement is driven by separate jacks 13 and 14. In a simpler embodiment (Fig. 3A), the hooking member 11 consists of a jack 13, a hook 15, jack-connection 16 and sled- connection 17. The sliding member 12 consists of a sliding-track 18, a jack 14 and a jack-connection 19. The sled-connection 17 of the hooking member 11 is attached to the jack 14 of the sliding member 12 (not shown in this drawing). In a more advanced embodiment (Fig. 3C), the hooking member 11 consists of a jack 13, a resistance pin 20, a hook 15, a jack-connection 16 and sled-connection 17. The role of the components will be described in more detail in relation to the function of the apparatus in the text describing figs. 3 and 4. The sliding member for the hooking member shown is Fig. 3C is identical to the sliding member shown in Fig. 3B. In figure 4, the function of a gripping means is shown for the hooking member 11 shown in Fig. 3A. In figure 4A, the gripping means 7 is in a position, where both the hook 15 and jack-connection 16 are in an open position (position A). A single pin 21 of a metal mesh mat 1 is shown under the gripping means 7 for simplification. In fig. 4B, the hook 15 has been placed in hooking mode as the jack 16 puts the hook 15 in position B, while the jack-connection 19 of the sliding member 12 is still in position A. In fig. 4C, the jack 14 of the sliding member 12 has moved the hooking member 11 towards the pin 21 and both the hook 15 and jack-connection 19 are in position B. In fig. 4D, the hook 15 has been locked around the pin as the jack 13 puts the hook 15 in position C, while the jack- connection 19 of the sliding member 12 is still in position B.

In figure 5, the function of a gripping means is shown for the hooking member 11 shown in Fig. 3B. Figure 5A shows a gripping means where both the hook 15 and jack- connection 16 are in an open position (position I). A single pin 21 of a metal mesh mat 1 is shown under the gripping means 7 for simplification. The tip of the resistance pin 20 reaches below the surface of the gripping means 7 that faces the metal mesh mat 1. In fig. 5B, the jack 14 of the sliding member 12 has moved jack-connection 19 in position II during which the resistance pin 20 hits the pin 21 of the metal mesh mat 1. When the resistance pin 20 hits the pin 21 of the metal mesh mat 1, jack 13 is activated to go towards position II. In fig. 5C, the jack 14 of the sliding member 12 remains in position II and jack 13 is now in position II locking hook 15 around the pin 21.

In figure 6, the bending means of the apparatus is outlined. The bending means of the apparatus comprises a telescopic boom 9 with adjustable length and a crossbar 10 connecting the guiding strips 8 and the telescopic boom 9. In figure 6A, the

bending/forming means is in a neutral position or gripping position, which is the same position as is shown in Fig. 2. In figure 6B, the bending means is bending the metal mesh mat (not shown in the drawing) transversally. In order to do so, the length of the telescopic boom 9 is extended and the crossbar 10 is attached/fixed to the end of the telescopic boom 9 so that the crossbar is pushed down with the telescopic boom 9. In figure 6C, the bending means is bending the metal mesh mat (not shown in the drawing) in a lengthwise direction. In this embodiment, the length of the telescopic boom 9 is extended, but the crossbar 10 is not attached/fixed to the end of the telescopic boom 9 so that the crossbar is not pushed down with the telescopic boom.