JP2003512535A - Sintered carbide tools for woodworking - Google Patents

Abstract

  (57) [Summary] The present invention relates to a cemented carbide having good properties for wood working tools. This is achieved by using very fine particle size WC powders and Co and / or Ni powders made by the polyol process. This cemented carbide is particularly useful in the processing of chipboard, chipboard, and medium and high density fiberboard (MDF / HDF).

Description

Detailed Description of the Invention

The present invention relates to cemented carbides having good properties for use as woodworking tools. More particularly, the invention relates to sintered, very fine-grained cemented carbide materials. Here, the corrosion and oxidation resistant phases are dispersed in a single phase binder based on nickel and cobalt and one or more of chromium, molybdenum, iron and vanadium. Most particularly, the binder is based on nickel and / or cobalt powder made by the polyol process.

Sintered carbides typically incorporate WC, Ni, Co and other powdered raw materials as well as organic binders (typically based on waxes) and mix them in a ball mill prior to spray drying the slurry. And made into a free-flowing, easily compressible powder. However, most powdered sources of Ni and Co are made by calcination of oxalates or hydroxides followed by reduction in a hydrogen atmosphere. These powders generally have a broad particle size distribution and contain strongly agglomerated particles. These particles are difficult to deagglomerate, even by ball milling. This results in Co agglomerates and inhomogeneous cemented carbide microstructures, which can result in changes in physical and chemical properties.

The polyol cobalt and nickel powders obtained according to the description of US Pat. No. 4,539,041 have predominantly nearly spherical particles with a non-aggregated average particle size of submicron size. The use of polyol powders as binders for cemented carbides is described in US Pat. No. 5,441,693. The use of a polyol powder source results in a relatively uniform microstructure due to the better dispersion of the binder phase particles. As a result, the amount of binder phase mass after sintering is relatively small, and the sintering temperature can be lowered.

Sintered carbide is one of the most popular materials currently used in the wood industry for woodworking tools. In order to obtain a relatively long service life and cutting performance of woodworking tools,
It is important to optimize certain properties of the cutting tool material. Two of the most important properties of woodworking tools are resistance to corrosion and oxidation and hardness.

These tools can be used not only for solid wood, eg logs, but also for artificial articles based on wood chips, fibers or chips, eg chipboards, particles.
Various types of corrosion are important as they are also used to process boards) and medium and high density fiberboard (MDF / HDF): o Solid wood is an organic that degrades the binder of the tool material. It contains acids and other compounds, which results in the shedding of hard WC particles from the matrix and wears the tool material. O Artificial wood articles contain organic binder materials based on compounds such as urea, formaldehyde, waxes, adhesive fillers, etc. and are optionally laminated with a plastic layer such as melamine. When processing these wood articles,
Temperatures can be very high (greater than 500 ° C.) at which time the components of the product decompose into corrosive compounds that chemically attack the cemented carbide binder. In addition, elevated temperatures can lead to oxidation of the cemented carbide binder, as well as deterioration and wear of the cutting edge.

The hardness should normally be as high as possible, thereby maintaining a sharp, wear-resistant cutting edge. The factors that determine hardness are primarily particle size and binder content. The hardness is usually relatively high when the particle size is relatively small and / or the binder content is relatively low. In general, a compromise must be made between particle size and binder content in order to obtain optimum sinterability, for example to reduce the porosity of the sintered green compact and to lower the sintering temperature. Very fine particle sizes usually require a higher binder content than with slightly larger particle sizes in order to properly and uniformly wet the WC particles with the binder component. The effect of grain size on Ni-based corrosion resistant cemented carbides for woodworking is disclosed in EP 0568584.

The problem is that with the use of highly agglomerated standard Ni and Co powder sources, non-uniform microstructure, sintered porosity and property differences within the material are avoided while avoiding very fine grain sizes and low particle sizes. It is to make a cemented carbide with a binder phase content.

In order for the cemented carbide material to work optimally, it is important that the microstructure be as uniform as possible. The polyol binder phase component promotes an optimal distribution of the binder phase around the ultrafine WC particles, allowing a combination of very fine WC particle size and low binder content.

The present invention is primarily directed to cemented carbide articles having a single phase binder phase that is corrosion resistant and resistant to oxidation, particularly woodworking cemented carbide articles, and includes substantially spherical submicron nickel made by the polyol process and And / or the use of cobalt powder. The polyol Ni- and Co-powder will be made separately by the polyol process, preferably as a mixture of Ni and Co by the polyol process. The total content of this binder phase is 0.5 to 30 wt%, preferably 1 to 10 wt%, most preferably 1.5 to 5 wt%, with the balance being tungsten carbide. The composition of the binder phase is 30 to 80 wt% Co, 5 wt% maximum Mo, 15 wt% maximum Cr, 10 wt% maximum V, 20 wt% maximum Fe, and the balance N.
i will be. The average sintered WC grain size will be less than 0.7 μm, preferably less than 0.5 μm, most preferably less than 0.3 μm.

Chipboard, particle board, and medium and high density fiberboard (MDF / HD
In a particularly advantageous and preferred embodiment for the processing of F), the cemented carbide comprises 2.3 wt% Co, 0.9 wt% Ni, and 0.3 wt% Cr with the balance being tungsten carbide. The average sintered WC grain size is less than 0.5 μm, preferably less than 0.3 μm.

The invention also relates to tools for the cutting and processing of wood and wood-based articles, in particular chipboards, particle boards, and medium and high density fiberboards (MDF / HDF), such as saw tips. Or throw-away tip (inde
xable insert) relates to the use of cemented carbide with a very fine sintered grain size and a binder phase containing Ni and Co made by a polyol process.

The present invention further comprises grinding, compacting and sintering the powders which make up the hard element and binder phase,
By powder metallurgy, whereby the binder phase contains Ni and / or Co made by the polyol process, and a binder phase based on Ni and Co and any of Mo, Cr, Fe and V. Based on a method of making a cemented carbide body. Preferably the sintering is carried out by gas pressure sintering, also referred to as sintered HIP.

The advantages provided by the use of the polyols Ni and / or Co are mentioned as being the relatively uniform microstructure and thus the improved chemical and physical properties.

Example 2.3 Containing 2.3 wt% Co, 0.9 wt% Ni and 0.3 wt% Cr,
An alloy (A) whose balance is tungsten carbide having an average sintered grain size of 0.2 μm is 1.9.
wt% Co, 0.7 wt% Ni, 0.3 wt% Cr and 0.1 wt% M
The alloy (B) containing o and the balance being WC having an average sintered grain size of 0.8 μm was tested. The average sintered WC grain size was determined by scanning electron micrographs obtained with an apparatus equipped with a field emission gun. The evaluation was carried out by using a semi-automatic device in consideration of the shape effect.

Both articles were made using conventional cemented carbide technology. In the prior art, powdered Co and Ni powders are made by reduction of Co- and Ni-oxalates, and in the present invention, powdered Co and Ni powders are Co- and Ni thermally reduced in polyol.
-Made from hydroxide to obtain a powder with an average particle size of submicron size.

The test involves machining a plank plate with a cutting edge tool having three identical indexable inserts. Cutting speed is 18,000 rpm, feed speed is 1 m
/ Min, and the cutting depth was 2 mm.

[0017]   Cutting distance (m) Wear of present invention A (μm) Wear of prior art B (μm)     1,300 36 45     4,000 58 72

The test results show that the wear of the alloys made according to the present invention is 2 compared to the prior art.
It is clear that it has decreased to 0%.

─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Fuller, Peter             Coventry Sea Buoy 4, England             7 DN, Canon Park, Stair               Green 35 (72) Inventor Dougard, Christian             Deko 2800 Ringbi, Denmark             ー, Krakasby 56 F-term (reference) 4K018 AD06 BA04 BA11 BB04 BB05                       KA15 KA16

Claims (6)

[Claims] 1. A binder phase based on 0.5 to 30 wt% Ni and Co, and the balance tungsten carbide having an average sintered grain size of less than 0.7 μm, preferably less than 0.5 μm, most preferably less than 0.3 μm. A cemented carbide for woodworking, comprising:
A cemented carbide for woodworking, characterized in that the Ni and / or Co source of the binder phase is a powder made by a polyol process as separate Ni and Co, preferably as a mixture of Ni and Co. 2. The cemented carbide for woodworking according to claim 1, wherein the binder phase contains 30 to 80 wt% of Co. 3. The binder phase comprises Mo at a maximum of 5 wt% and a maximum of 15 w.
The cemented carbide for woodworking according to claim 1 or 2, characterized in that it contains t% Cr, maximum 10 wt% V and maximum 20 wt% Fe. 4. The cemented carbide for woodworking according to claim 1, wherein the content of the binder phase is 1 to 10 wt%. 5. The cemented carbide for woodworking according to claim 1, wherein the content of the binder phase is 1.5 to 5 wt%. 6. A binder phase based on Ni-Co containing ultrafine tungsten carbide and 0.5 to 30 wt% Co and Ni made by a polyol process, and optionally Mo, Cr, V and / or. Use of sintered carbides containing Fe for the cutting and processing of wood or wood-based articles, in particular chipboards, particle boards, and medium and high density fiberboards (MDF / HDF).