Improvement to a cutting tool, a circular saw blade – by fastening its inserts to teeth thereof, by means of screws and guide angles

Abstract

The present utility model application relates to an improvement to the fastening of the inserts to the teeth of circular saw blades, by combining guide angles positioned on the backs of tooth housings, which receive and couple the inserts, with the tightening of the tip of a handle located between the teeth of the saw blade, by installing screws on the fastening handles, which when tightened, generate a moment of force, propelling the insert against the housing and allowing the fastening thereof, wherein the centring and alignment of the inserts on the same orthogonal plane is achieved by means of guide angles inserted into the backs of the tooth housings, forming high-precision fittings for receiving and coupling the inserts.

Description

[0001] IMPROVEMENT INTRODUCED TO THE CIRCULAR SAW BLADE CUTTING TOOL - FIXING THE INSERTS IN THE TEETH BY MEANS OF SCREWS AND GUIDE ANGLES.

[0002] 01 - This application for a utility model invention patent refers to the improvement introduced in the circular saw blade type cutting tool, more specifically in the fixing of the interchangeable inserts in the teeth by tightening the screws installed in the pockets between the teeth and introducing guide angles (V-shaped chamfers) on the back of the housings in the teeth, widely used for cutting various types of commercially available materials, from wood to steels with high hardness, different gauges and profiles.

[0003] 02 - The reasons that lead companies to use circular saw blades are due to the fact that the cutting operation with said saw blades provides fast, precise cuts, with an excellent finish, giving industrial processes extremely high productivity.

[0004] 03 - The development of new methods for fixing inserts in circular saw blades occurs because the conventional process (brazing) generates limitations, such as: the impossibility of using coating layers deposited by methods that require high temperatures, such as chemical vapor deposition (CVD), reducing performance and increasing the manufacturing / recovery time of said tools, among others.

[0005] 04 - In the state of the art, BR 10 2013 017641-9 issued on 11 / 16 / 2022 presents the fixation of the insert in the tooth housing, being carried out by means of a screw in the center of the insert, to center the housing and avoid axial movements during cutting, a pivot pin is installed located in the front part of the insert and at the base of the housing. However, with the current reduction in the thickness of saw blades, it becomes unfeasible to place a screw in the center of the insert and a pin at its base, since in thinner saw blades, there is not enough space for the aggregation of these components without affecting the solidity and safety of the tool.

[0006] 05 - BR 20 2017 003809-8, issued on 10 / 04 / 2022, defines the use of a tightening screw located in the pocket between two consecutive teeth to fix the insert in the tooth housing of the circular saw blade. To center the insert in the housing and prevent axial movement during cutting, a pivot pin is placed between the base of the housing and the back of the insert. As in the previous patent, with the reduction in the thickness of saw blades, it becomes unfeasible to place a pivot pin in the back of the insert, since in thinner saw blades, there is not enough space for adding this component without affecting the solidity and safety of the tool.

[0007] 06 - The improvement now introduced in the cutting tool, circular saw blade - fixing the inserts in the teeth by tightening the screws and introducing guide angles (V-shaped chamfers) on the back of the housings in the teeth, which is the subject of this patent application in the utility model modality, presents the fixing of the inserts in the circular saw blade disc being carried out by tightening the screws positioned in the handles and pockets existing between two consecutive teeth.

[0008] 07 - The handle represents a force lever for positioning the insert and is formed by the gap (regardless of size and shape), existing between the base of the insert housing and the pocket between two consecutive teeth, where a screw is installed in the handle region, which when tightening the screw on the handle, the moment of force (torque) occurs, resulting in the displacement of the tip of the handle towards the insert, like a lever, pressing the insert against the housing existing in the tooth, providing robust fixation of the insert to the disc.

[0009] 08 - To ensure centering and alignment of the inserts in the same orthogonal plane, avoiding unwanted axial movements during cutting, guide angles (V-shaped chamfers) were introduced on the backs of the existing tooth housings, forming high-precision fittings for receiving and coupling the inserts. It is worth noting that the centering pivot pin was definitively eliminated in this design due to lack of space in thinner blades.

[0010] 09 - To manufacture the saw blade disc, a laser cutting process is performed, where the disc's characteristics are introduced into the steel plate, such as: diameter, central and drag holes or keys, clamping handles, insert housing, among others. This process generates residual stresses in the cut body, especially in the areas of the insert clamping handles, because their mass is reduced relative to the main body of the saw blade.

[0011] 10 - Residual stresses are properly relieved by vibration during the first forty minutes the saw blade is subjected to cutting. Relieving residual stresses eliminates the possibility of cracks and subsequent breakage. This invention allows the manufacture of saw blades of any size and thickness, as the inserts are attached directly to the tooth housings, without the need for centering pivot pins and screws installed directly on the inserts. This provides greater mechanical strength in a reduced space, enabling the manufacture of saw blades with narrower thicknesses. It also allows the inserts to be mounted at any angle of attack or inclination, meaning the inserts can be fixed in the positive, negative, or neutral position.

[0012] 12 - A circular saw blade is a tool used for cutting various types of materials, whether for dividing raw materials into parts, opening channels, and cutting with high dimensional precision, among other things. Circular saw blades are manufactured using specific technologies. In general, all saw blades are made of special steels, with diameters compatible with the equipment to which they will be mounted and the materials to be cut. They have a central hole and, occasionally, some drive holes or keys for attachment to the cutting equipment (saw machine), on drive shafts that impose controlled rotations to cut the parts by removing chips.

[0013] 13 - The existing types of circular saw blades are: friction, solid high-speed steel, with high-speed steel or alloyed carbon steel segments, with inserts fixed to the periphery of the blade, or with inserts fixed to the saw blade teeth. We emphasize that this patent application focuses only on an improvement for circular saws with inserts fixed to housings inserted into the saw blade teeth.

[0014] 14 - In recent times, cutting tool coatings have gained significant importance, ensuring superior performance compared to uncoated tools when cutting a wide range of materials, including ferrous and non-ferrous metals, and steels. Another characteristic of coatings is the variety of specific chemical compositions available, depending on the materials being cut, in their various shapes and qualities. This contributes to improving the surface integrity of the cut piece, such as reduced roughness, improved straightness, and increased performance, among others.

[0015] 15 - The essential properties of coatings are good adhesion to the substrate, hot hardness, high oxidation point, chemical stability, low chemical affinity with the material being cut, residual compressive stresses and low thermal conductivity.

[0016] 16 - There are two coating application processes that can be used for carbide and cermet tools: PVD (physical heat deposition) and CVD (chemical vapor deposition). a. Physical Vapor Deposition (PVD): Its main characteristic is the process temperature range, which is around 500°C, and its main benefit is maintaining the toughness of the tool substrate. b. Chemical Vapor Deposition (CVD): This process uses high temperatures (approximately 1000°C), which does not imply metallurgical changes in the carbide or cermet, but thermally affects the metallurgical structure of the tempered steel discs. The advantage of this process is greater resistance to crater wear.

[0017] 17 - The main type of wear that occurs on circular saw inserts during machining is cratering, which occurs on the cutting edge and rake surface of the tool, the interface between the tool and the chip. Its occurrence is due to a combination of wear mechanisms called diffusion and adhesion. Diffusion occurs at high temperatures and consists of the transfer of atoms between the workpiece and tool material. Adhesion occurs when two metal surfaces are brought into contact under moderate load and low cutting speeds, thus forming a metallic layer between them.

[0018] 18 - The manufacture of circular saw blades with inserts comprises the following operations: acquisition of raw materials and supplies, heat treatment, laser cutting of the disc, grinding of the disc faces, fixing the inserts in the disc housings, straightening, tensioning the saw blade and sharpening the inserts.

[0019] 19 - To attach the inserts to the saw blade, the brazing process is used. This consists of joining the insert to the saw body through electrical induction heating at a temperature below their melting point. Silver solder (filler metal) is added, which changes from a solid to a liquid state and flows between the surfaces of the insert and the housing, forming a layer that, when cooled, provides the expected adhesion.

[0020] 20 - Brazing inserts to the body of a circular saw blade has the advantage of good compressive strength. However, it has the disadvantage of limiting the use of coating layers, as it is only applied using the PVD (physical vapor deposition) process to small saw blades proportional to the available furnace size.

[0021] 21 - The use of CVD in circular saw blades represents a good alternative to mitigate insert wear, however this technology does not apply to saw blades with brazed inserts, since the application of CVD occurs at a temperature higher than that of brazing, and since the CVD application temperature is higher than that of brazing, during the CVD application process, the inserts would come loose from the housings.

[0022] 22 - The limiting factor is the high temperature required by the process. The first problem is that the melting temperature of the filler metal is approximately 750°C, so if CVD were used, the inserts would detach from the saw blade during the process, since the process occurs at 1000°C. Another factor is that when the saw blades are subjected to the coating temperature, they undergo irreversible metallurgical transformations and plastic deformations, rendering them unusable for application due to the lack of stability and operational safety of the tool.

[0023] 23 - The objective of the invention of this utility model patent application is to improve the fastening of inserts in the housings existing in the teeth of circular saw blades, with the aim of enabling the use of coated inserts by both the physical vapor deposition (PVD) process and the chemical vapor deposition (CVD) process and to optimize the manufacturing / recovery of circular saw blades regardless of their dimensions. Specifically, fastening will be achieved by tightening the screw positioned in the pocket existing between two consecutive teeth that moves the handle as a force lever, securing the insert in the housing existing in the saw blade tooth. To ensure that the inserts are centered and prevent their axial movement during cutting, guide angles (V-shaped chamfers) are introduced into the insert housing.Eliminate the centering pivot pin, due to lack of sufficient space for its assembly on narrow saw blades.

[0024] 24 - The technological development of cutting tools is essential to enable the use of technologies that increase their performance and meet market demands such as the need to optimize the manufacturing / recovery of said tools, and when we specifically deal with the circular saw blade tool with fixed inserts in its teeth, the coating of the inserts is an excellent alternative to improve the mechanical properties of the tool, in addition to substantially increasing its performance and lifespan.

[0025] 25 - It is common to use the brazing process to fix the inserts to the disc body, however, the saw manufactured by this process is limited to the use of physical vapor deposition (PVD) coating, applied only to small saw blades, proportional to the size of the furnace, which although it increases the tool's performance, its efficiency is very limited compared to the chemical vapor deposition (CVD) process.

[0026] 26 - The present invention aims to improve the fixing of inserts in the saw tooth housings by tightening the screws existing in the handles between two consecutive teeth, whose movement generated by the moment of force (torque) created by tightening the screw and consequently of the existing handle, fixes the insert in the disc. The coupling and centering of the inserts is carried out through the guide angles (V-chamfers) introduced in the backs of the housings inserted in the disc teeth. J - As this document is a complement to the Letters Patent entitled "Improvement introduced in the circular saw blade cutting tool - Fixing the inserts in the teeth", numbers BR 10 2013 017641-9 and BR 20 2017 003809-8, the figures below will illustrate the differences between the Letters Patent and the new patent application. Figures 1 and 2 show the improvement of Patent Letter BR 10 2013 017641-9 issued on 11 / 16 / 2022.Figure 1 shows the detail of the circular saw blade teeth where: (A) the saw blade disc, (B) the insert, and (C) the screw. Figure 2 illustrates the cross-section of the circular saw blade where: (A) the saw blade disc, (B) the insert, (C) the screw, and (D) the fixing pin. Figures 3 and 4 show the improvement of Letter Patent BR 20 2017 003809-8 issued on 10 / 04 / 2022. Figure 3 illustrates the detail of the circular saw blade teeth where: (A) the saw blade disc, (B) the insert, and (C) the screw. Figure 4 shows the cross-section of the circular saw blade where: (A) the saw blade disc, (B) the insert, (C) the screw, and (D) the fixing pin. Finally, Figures 5, 6 and 7 illustrate the improvement of the present utility model patent application. Figure 5 shows the detail of the circular saw blade teeth where: (A) the saw blade disc, (B) the insert and (C) the screw.Figure 6 illustrates the detail of the saw blade teeth without the inserts and screws where:.

[0027] (A) the saw blade disc and (D) guide angles (V-bevels). Figure 7 shows the cross-section of the circular saw blade where: (A) the saw blade disc, (B) the insert and (C) the screw.

Claims

MODIFIED CLAIMS Received by the International Secretariat on 18 December 2024 (18.12.2024) 1 - IMPROVEMENT INTRODUCED IN THE CIRCULAR SAW BLADE CUTTING TOOL - FIXING THE INSERTS IN THE TEETH BY MEANS OF SCREWS AND GUIDE ANGLES, circular saw blade type cutting tool (A) where the inserts (B) are fixed by being carried out by means of a screw (C) and guide angles (V-bevels) (D) to allow the coating of only the insert by means of chemical vapor deposition (CVD), characterized by the fact that the fixation will occur by means of tightening the screw (C) positioned in the pocket existing between the two consecutive teeth that generates the moment of force (torque), holding the insert (B) in the housing existing in the saw blade tooth (A), and to ensure that the inserts are centered and prevent their axial movement during cutting, guide angles (V-bevels) (D) are introduced in the insert housing. insert. MODIFIED SHEET (ARTICLE 19) Declaration under Article 19(1) IA Number: PCT / BR 2024 / 050041 International Deposit Date: 02 / 05 / 2024 Submission date: 12 / 18 / 2024 We declare for all due purposes that the claim presented has only undergone changes in the original text, thus including the mentions (B) and (A) in the text, for better adaptation, as per table VII of the written opinion of the authority responsible for the international search.

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