Chain cutting machine for stone

Abstract

 The invention relates to a chain cutting machine and, in particular, it relates to a lubrication method of the contacting surfaces between the chain links (31) and a guide executed in the blade body, on which said chain slides. The blade body provides at least one lubricant input duct executed in the blade body through a channel that extends parallel to the perimeter of the blade, and a plurality of holes that connect said channel with the sliding zone. According to another aspect, each link of the chain comprises a cutting tip holder (11) that holds at least one cutting tip (12), equipped with engagement means (14), so called brackets, for connecting the cutting tips (12) to said cutting tip holders (11) by friction caused by the pressure of the bracket (14). This way, for changing a worn cutting edge it is not necessary to unscrew completely the fastening screw (15) of the cutting tip, but a few unscrewing turns are enough for loosening the cutting tip and changing its position.

Description

Field of the invention

[0001] The present invention relates to a machine for making tunnels and for excavation of stone products in quarries. In particular, it relates to a lubrication method of the contacting surfaces between chain links and a guide executed in the blade body, on which said chain slides. According to another aspect, the invention relates to an element of engaging the cutting tips to a cutting tip holder.

Description of the prior art

[0002] As well known, chain cutting machines are designed for cutting stone by operating a cutting tool, mounting a plurality of elements, so called "links", which are arranged in succession and connected to each other to form a chain loop. The chain loop is dragged about a thin elongated support element, so called "blade", which in use is oriented according by the worker. The blade, along its perimeter, has a sliding guide on which the chain is driven by pinion gear.

[0003] The cutting process is assisted in the cutting zone by a significant liquid flow, which has the object of cooling the tools, of removing the powder ground during the cutting process and of washing the cutting tips.

[0004] Methods are known for spreading said cooling liquid through an input duct that extends for all the length of the blade, from which secondary ducts depart that end on the perimeter of the blade, within the blade width.

[0005] Sometimes, the same liquid used as coolant is used also for lubricating the contacting surfaces of the links and of the guiding guide, avoiding in this way to use mineral oils for lubrication.

[0006] A drawback with the use of said cooling liquid is the big amount thereof, which is polluting for the environment and cannot be re-used because it is mixed with stone powder.

[0007] Another problem connected to chain cutting is indicated hereafter.

[0008] Often the cutting tips are not integrated to the cutting tip holders, but are fixed to them. They can have the shape of a prism, frustum of cone or pyramid and, normally, have many sharp edges, so called "cutting edges", capable of biting the stone to cut.

[0009] When a cutting edge is worn, the cutting process is stopped and the cutting tip is rearranged so that it presents a new sharp edge. When all the cutting edges are worn, the cutting tip is removed and replaced.

[0010] The cutting tips are made of a high hardness material, for example hard metal alloys or sintered materials, normally of oxides or ceramics; the cutting tips normally have a central hole for fixing to the cutting tip holder by means of screws.

[0011] A limitation to this system is due to downtime, so called "presetting", necessary for positioning the cutting tips, so that a worn cutting edge is replaced by a sharp edge. Furthermore, the positioning step is complicated by the ground powder encrusting the screw heads thus impeding the access for removal of the screws. Once loosened, a screw must be extracted, the cutting tip must be rotated, the screw must be tightened again and these operations must be repeated for all cutting tips.

[0012] Another drawback is that the cutting tip holder is weakened by the presence of as many screw-threaded holes as many the cutting tips housed in it are.

[0013] There is then the need to provide a device that assists the operations of changing the cutting edges, reducing the number of operations and reducing the number of holes in the cutting tip holder .

Summary of the invention

[0014] It is a feature of the present invention to provide a chain cutting machine that does not need a large amount of coolant, but that is capable to dry-cut, thus reducing the environmental impact that would be caused by the dispersion of large amounts of mud consisting of ground powder and coolant.

[0015] It is, in particular, a feature of the invention to provide, by an effective system of lubrication, a cutting machine that can operate also without using a coolant, i.e. to dry-cut, or that at least substantially reduces the amount of coolant used.

[0016] Another feature of the present invention is to provide a chain cutting machine that uses cutting tools that can be fixed easily so that the change of the cutting edges, once worn, is faster.

[0017] A further object of the invention is to provide a machine that uses cutting tip holders more resistant and solid with respect to the prior art.

[0018] These and other features are accomplished with one exemplary chain cutting machine according to the present invention, having a cutting tool comprising:

• a thin elongated support element, so-called "blade";
• a plurality of elements, so called "links", connected to each other to form a chain loop, which is slidingly dragged along its axis along the perimeter of said blade;
• a plurality of cutting tips integral to said links;
• a sliding guide extending along the perimeter of the blade on which operatively slides the chain;

   characterised in that it provides:

• at least one lubricant input duct executed in said blade parallel to its perimeter;
• a plurality of through holes executed in said blade and said sliding guide, for the flow of the lubricant from said lubricant input duct to the links sliding guide; whereby the lubricant, flowing through the blade and the guide reaches the contact surfaces of said links and of said guide.

[0019] Preferably, said lubricant input duct is obtained by a channel machined in the body of the blade, which starts from an inlet point close to the fastening point of the blade and proceeds parallel to the perimeter of the blade, for the whole length of the same. The channel is then closed by a cover for its whole length, creating a duct in the body of the blade.

[0020] Advantageously, said cover is plate shaped and houses in a recess executed in the blade and that follows its shape, while allowing the cover to remain operatively blocked therein.

[0021] According to another aspect of the present invention, a chain cutting machine has a cutting tool comprising:

• a thin elongated support element, so-called "blade";
• a plurality of elements, so called "links", connected to each other to form a chain loop, which is slidingly dragged along its axis along the perimeter of said blade;
• a plurality of cutting tips integral to said links;
• a plurality of elements, so called "cutting tip holders", which support said cutting tips and remain integral to said links;
• a sliding guide extending along the perimeter of the blade on which operatively slides the chain;
  wherein said plurality of cutting tips is characterised in that of providing:

• engagement means, so called "bracket", for connecting said cutting tips to said cutting tip holders by the friction caused by the pressure of the bracket on the cutting tip;
• screws for fastening the brackets to the cutting tip holders;
  whereby, for changing a worn cutting edge it is not necessary to unscrew completely the fastening screw, but a few unscrewing turns are enough for loosening the cutting tip and changing its position.

[0022] Preferably, each bracket uses a single fastening screw to the cutting tip holder, to assist and speeding up the operations of changing a worn cutting edge.

[0023] Advantageously, if the cutting tip holders houses more than one cutting tip, a single bracket can be used, reducing, thus, the number of holes necessary for fixing the cutting tips and increasing the mechanical resistance of the cutting tip holder.

[0024] In particular, a same chain can use cutting tip holders with shapes different from each other and can house cutting tips mounted with angles different from each other to provide in the stone a cross section of the cut resulting from the overall action of all the cutting tips.

Brief description of the drawings

[0025] The invention will be made clearer with the description of an embodiment thereof, exemplifying but not limitative, with reference to the attached drawings wherein:

• figure 1 shows an elevational view of the blade of a chain cutting machine;
• figure 2 shows a cross section perpendicular to the axis of the blade according to arrows II-II, shown in figure 1;
• figure 3 shows a perspective view of an assembled link of the chain on which a cutting tip holder is mounted with its components;
• figures 4, 5 and 6 show respective perspective views of three different configurations of the cutting tip holder;
• In figure 7 a possible succession is shown of different cutting tip holders, which work in succession on the coupled guiding surfaces of the chain, and form together a desired cutting profile;
• figure 8 shows an elevational front view of the cutting tips, mounted in turn on different cutting tip holders, and forming together a desired profile;
• figures 9, 10 and 11 show respectively a side view, a front and a top plan view, of complete cutting tip holder for showing the cutting angles of the cutting tip.

Description of a preferred exemplary embodiments.

[0026] In figure 1 an overall view is shown of the tool of a chain cutting machine. This tool comprises a support body 30 with elongated shape, of minimum thickness with respect to the transversal size, so-called "blade". On the perimeter of blade 30 a chain loop is dragged comprising a plurality of links 10 on each of which a cutting tip holder is mounted. The chain loop slides in a U-shaped guide closed laterally from side plates 5 and 5', connected laterally with respect to the blade by means of screws, for example in number of five for each plate, in a way not shown in the figure, and closed below by a T-shaped guide. The tool of the cutting machine needs a lubrication for example with mineral grease, for reducing the friction between the coupled guiding surfaces and the chain. Lubrication is obtained with two channels 1 and 1' that extend along a edge of blade 30 for its length within its perimeter, and which are closed to form ducts by respective covers 3 and 3' that follow its form. The covers are connected on blade 30, for example, by means of screws in a way not shown. The lubricant, moreover, starting from said channels 1 and 1', reaches the sliding zone through a plurality of holes 2 and 2' parallel to the mid-plane of the blade and that cross the blade and the T-shaped guide.

[0027] The tool of the chain cutting machine is shown in cross section in figure 2, where blade 30 is shown on whose perimeter the chain is shown with two links 10 thereof, comprising a body 31 and a link element 32. The chain slides operatively in the guide obtained with side plates 5 and 5' and with T-shaped guides 6 and 6', connected by screws 7 and 7'. The lubrication system provides channels 1 and 1' closed by covers 3 and 3' connected to blade 30 with screws 4 and 4'. Parallel to the mid-plane, moreover, holes 2 and 2' cross both blade 30 and T-shaped guides 6 and 6'.

[0028] Figure 3 shows a complete link 10, which comprises link body 31, the link element 32 and cutting tip holder 11. Link body 31 and link element 32 are pivotally connected by pins 34, passing in hole 33. The cutting tip holder 11 is coupled to the link body by "dove-tail" engagement and fastened by a screw 13. Cutting tips 12 are held by cutting tip holders 11, for friction by the pressure on two opposite sides of a bracket 14, which is connected by tightening a screw 15 in a screw threaded hole present on the cutting tip holders 11.

[0029] Figures from 4 to 6 show three further examples of cutting tip holders, in particular, figure 4 shows a cutting tip holder 11 with two aligned cutting tips 12 locked with a bracket 14 and screw 15. Figure 5 shows a cutting tip holder 11 with a single cutting tip 12 blocked on the right edge with bracket 14 and screw 15. Similarly, in figure 6 a cutting tip holder 11 is shown with a single cutting tip 12 blocked on the left edge with bracket 14 and screw 15.

[0030] Figure 7 shows a possible succession of cutting tip holders 10, mounted on respective link bodies in a way not shown in the figure. The whole succession, operatively, forms a whole desired cutting profile, each cutting tip contributing for a portion thereof. The overall projection of the profiles of the cutting tips 12 of a whole succession is shown in figure 8.

[0031] An example of geometry of assembled cutting tips and then of the angles that form the profiles of the cutting tips, so called "cutting edges", is shown in figures from 9 to 11. Figure 9 is an elevational side view and enhances the possible angle for assembling the cutting tip 12, having a lower rake between 5° and 15°. Figure 10 is an elevational front view that shows the main cutting angle that has to be less than 12°. Figure 11 shows a top plan view of the complete cutting tip holders and in particular, the angle of inclination of the cutting tip 12 with respect to the axis of the chain. Another arrangement for correct operation is that of positioning the profile of the cutting edge main at a distance set between 5 and 15mm from the fastening hole of the cutting tip holders to the link body.

[0032] The foregoing description of a specific embodiment will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt for various applications such an embodiment without further research and without parting from the invention, and it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to the specific embodiment. The means and the materials to realise the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Claims

1. Chain cutting machine, having a cutting tool comprising:

- a thin elongated support element, so-called "blade";

- a plurality of elements, so called "links", connected to each other to form a chain loop, which is slidingly dragged along its axis along the perimeter of said blade;

- a plurality of cutting tips integral to said links;

- a sliding guide extending along the perimeter of the blade on which operatively slides the chain;

   characterised in that of providing:

- at least one lubricant input duct executed in said blade parallel to its perimeter;

- a plurality of through holes executed in said blade and said sliding guide, for the flow of the lubricant from said lubricant input duct to the links sliding guide; whereby the lubricant, flowing through the blade and the guide reaches the contact surfaces between said links and said guide.

2. Chain cutting machine, according to claim 1, wherein said lubricant input duct is obtained by a channel machined in the body of the blade, which starts from a inlet point close to the fastening point of the blade and proceeds parallel to the perimeter of the blade, for the whole length of the same, said channel being closed by a cover following the whole channel, thus creating a duct in the body of the blade.

3. Chain cutting machine, according to claim 2, wherein said cover is plate shaped and is housed in a recess executed in the blade and that follows its shape, while allowing the cover to remain operatively blocked therein.

4. Chain cutting machine having a cutting tool comprising:

- a thin elongated support element, so-called "blade";

- a plurality of elements, so called "links", connected to each other to form a chain loop, which is slidingly dragged along its axis along the perimeter of said blade;

- a plurality of cutting tips integral to said links;

- a plurality of elements, so called "cutting tip holders", which support said cutting tips and remain integral to said links;

- a sliding guide extending along the perimeter of the blade on which operatively slides the chain;

wherein said plurality of cutting tips is characterised in that of providing:

- engagement means, so called "bracket", for connecting said cutting tips to said cutting tip holders by the friction caused by the pressure of the bracket on the cutting tip;

- screws for fastening the brackets to the cutting tip holders;

whereby, for changing a worn cutting edge it is not necessary to unscrew completely the fastening screw, but a few unscrewing turns are enough for loosening the cutting tip and changing its position.

5. Chain cutting machine, according to claim 4, wherein each bracket uses a single fastening screw to the cutting tip holder, to assist and speeding up the operations of changing a worn cutting edge.

6. Chain cutting machine, according to claim 4, wherein if the cutting tip holders houses more than one cutting tip, a single bracket is used, and a single screw, reducing, thus, the number of holes necessary for fixing the cutting tips-and increasing the mechanical resistance of the cutting tip holder.

7. Chain cutting machine, according to claim 4, wherein said chain uses cutting tip holders with shapes different from each other and houses cutting tips mounted with angles different from each other so that, once mounted in turn on different cutting tip holder, they form an overall desired profile.

Drawing