CA1178065A - Phenolic resin bonded grinding wheels - Google Patents
Phenolic resin bonded grinding wheelsInfo
- Publication number
- CA1178065A CA1178065A CA000375745A CA375745A CA1178065A CA 1178065 A CA1178065 A CA 1178065A CA 000375745 A CA000375745 A CA 000375745A CA 375745 A CA375745 A CA 375745A CA 1178065 A CA1178065 A CA 1178065A
- Authority
- CA
- Canada
- Prior art keywords
- resin
- furfural
- grain
- abrasive
- amount
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G8/00—Condensation polymers of aldehydes or ketones with phenols only
- C08G8/04—Condensation polymers of aldehydes or ketones with phenols only of aldehydes
- C08G8/06—Condensation polymers of aldehydes or ketones with phenols only of aldehydes of furfural
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
- B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
- B24D3/02—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent
- B24D3/20—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent and being essentially organic
- B24D3/28—Resins or natural or synthetic macromolecular compounds
- B24D3/285—Reaction products obtained from aldehydes or ketones
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
- B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
- B24D3/34—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents characterised by additives enhancing special physical properties, e.g. wear resistance, electric conductivity, self-cleaning properties
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/04—Oxygen-containing compounds
- C08K5/15—Heterocyclic compounds having oxygen in the ring
- C08K5/151—Heterocyclic compounds having oxygen in the ring having one oxygen atom in the ring
- C08K5/1535—Five-membered rings
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Polishing Bodies And Polishing Tools (AREA)
Abstract
ABSTRACT
A grinding wheel is described which is bonded with a phenol formaldehyde resin based bond containing hexamethylenetetramine as the curing agent. The wheels are made by first wetting the abrasive with furfural in varying quantities relative to the amount of hexamethylenetetramine in the phenol formaldehyde resin. Different amounts of the curing agent require different specific amounts of furfural to produce optimum properties in the finished grinding wheel.
A grinding wheel is described which is bonded with a phenol formaldehyde resin based bond containing hexamethylenetetramine as the curing agent. The wheels are made by first wetting the abrasive with furfural in varying quantities relative to the amount of hexamethylenetetramine in the phenol formaldehyde resin. Different amounts of the curing agent require different specific amounts of furfural to produce optimum properties in the finished grinding wheel.
Description
TECHNICAL FIELD
The invention relates to organic polymer bonded grinding wheels. More specifically the invention is concerned with grinding wheels bonded with hexamethylenetetramine cured phenolic resin used for example as snagging wheels and cut-off wheels.
BACKGROUND ART - `
PRIOR ART STATEMENT
10The following patents are representative of the most relevant prior art known to the Applicants at the time of filing of the application:
UNITED STATES PATENTS
3,406,020 October 15, 1968 W. J. D'Alessandro 15FORElGN PATENTS
1,207,766 October 7, 1970 ~nited Kingdom In the manufacture of resin bonded grinding wheels, a measured amount of abrasive grain is mixed with a powdered phenolic resin based bonding composition, then the resulting mix is pressed to form a wheel shape and the resin is cured. To promote - a better pickup and bonding of the resin to the 11'71~65 abrasive grains, it has been found useful to wet the grains with furfural prior to mixing the grain with the resin bond composition. The U. S. Patent 3,406,020 to D'Alessandro, ~ctober 15, 1968 and British Patent to Norton Company, 1,207,766, published October 7, 1970, describe such a wheel making procedure.
D'Alessandro teaches the making of phenolic bonded abrasive wheels having various additives mixed with the grain and bond composition that are alleged to produce a bonded wheel having an enhanced flexural strength. Various kinds of abrasive grains such as alumina, corundum, silicon carbide and diamond grains are mentioned for inclusion in the wheel bonded with a novolak resin with hexamethylenetetramine hardening agent. The harden-ing agent is used within a range of about 2~ to 50% based on the weight of the novolak, the preferred range being from about 3~ to 20% and more particularly 7% to 15%. This patent describes the use of from 0 to about 100 parts of a wetting agent per hundred parts of novolak, the wetting agent being selected from a group consisting of liquid resole resin, cresol, furfural and furfural alcohol. The wetting agent is blended with the abrasive grain in proportions of about 40 parts liquid phenolic resin wetting agent to 80 parts powdered novolak binder and in another formulation of 10 to 20 parts furfural with 120 parts of solid novolak resin. The formu-30 lation is controlled so that the abrasive mixof grains, wetting agent and resin binder are free flowing at room temperature and the only criterion for determining how much wetting agent to use is that the mix should remain relatively 35 free flowing up to the time it is charged into the mold.
11~7~6~;
The British patent is concerned with the making of an improved self-dressing manually controlled foundry snagging wheel having a resin bond, the wheel having from 22% to 26% pores by volume and the abrasive being spinel or mullite grains or mixtures of such abrasive grits. The making of wheels of such porosity is described and in the preparation of the abrasive grain and resin bond from which the wheel is molded, with reference to the use of furfural, there is only one comment and it is said that furfural is used in a conventional manner as a plasticiser in an amount of 55 cubic centimeters per pound of dry resin bond. No mention is made of the amount of hexamethylenetetramine employed.
DISCLOSURE OF THE INVENTION
The present invention provides an improve-ment over the prior art with the disclosure of a relationship between the amount of furfural wetting agent used on the grain in relation to the amount of curing agent used in the resin bond.
Whenever the term "mix" is used herein it is meant to have that meaning well known in the grinding wheel art viz. a more or less granular mixture of abrasive grain coated with a powdered uncured polymer or resin. Similarly, when the terms "bond" or "resin bond" are used, these terms are intended to include bond made up of resin alone and those which contain one or more of the many fillers, grinding aids, and reinforcing media know in the art. It has been discovered tha~
the maximum grinding ratio for any given wheel specification can be more assuredly attained when a preferred quantity of furfural wStting agent is 11~7~ 5 applied to the grain prior to the mixing of the grain with the powdered phenolic resin bond.
The furfural is used to wet the grain and is added to the grain in a certain proportion with respect to the hexamethylenetetramine curing agent used, which itself is added in a particular quantity to the resin bond to control the durability character-istic of the cured wheel.
It is known that the durability of a phenolic bonded grinding wheel such as a snagging wheel or cut-off wheel can be improved by increasing the crosslink density of the phenolic resin bond - which is accomplished by increasing the amount of hexamethylenetetramine hardening agent used with the novolak resin. It has now been found that there is a unique relationship between the amount of ~urfural wetting agent applied to the grain in relation to the quantity of hardening agent used in the novolak resin bond composition, the quantity of wetting agent being varied in the manner taught herein in order to control the grinding ratio characteristic in the cured wheel.
It is therefore an object of this invention to provide a grinding wheel with improved durability and grinding ratio characteristics.
Another object is to provide a mixing procedure for relating the amount of furfural used to wet the grain to the amount of hexamethylene-tetramine hardening agent in the bond in order to produce a grinding wheel having an improved durability and grinding ratio.
Another object of this invention is to teach how snagging and cut-off wheels and the like may be produced to have a maximum grinding ratio for their respective specific compositions.
, 1~7~65 -4a-Thus, in accordance with the present teachings, a phenolic resin bonded grinding wheel is provided in which the hexa-methylenetetramine is the curing agent and furfural is the wet-ting~agent applied, at least in part, to the abrasive grain in the preparation of the wheel mix. The furfural is employed in an amount of from 20-60 cm3 per pound of resin with the furfural being incorporated in the wheel formulation in an in-creasing amount as the amou~t of hexamethylenetetramine curing agent in the resin increases from 12~ to 20% by weight.
In accordance with a further teaching, a method is provided of approving the grinding ratio and durability of a resin bonded abrasive grinding wheel where the abrasive grain is wetted with furfural before the grain is mixed with the powdered novolak resin which has a hexamethylenetetramine hardening agent therein.
The method provided comprises wetting the grain with furfural, then mixing the furfural wetted grain with a powdered novolak resin bond with the hexamethylenetetramine hardener therein, measuring out a total quantity of furfural in an amount related to the quantity of hexamethylenetetramine in the resin bond, the amount falling within the range of from 20-60cc of furfural per pound of resin when the hardening agent is present in from 12%
to 20% by weight of the resin mix.
~t~8~6S
Other objects will appear in the specifi-cation below.
BRIEF DESCRIPTION OF THE DRAWINGS
The figure is a chart showing the variation of the grinding ratio of the finished abrasive wheels made in accordance with this invention by varying additions of furfural wetting agent added to the grain in relation to the quantity of hexamethylenetetramine hardening agent in the resin.
THE PREFERRED EMBODIMENTS
While the following discussion of the preferred embodiments is directed specifically at novolak resin i.e. phenol-formaldehyde condensate, it should be understood that other phenolic based polymers are within the scope of the invention e.g. modified phenol-formaldehyde resins, phenol-furfural resins and the like. The term "phenolic resin" as used herein, is intended to include such hexamethylenetetramine curable resins.
Conventional resin bonded grinding wheels that are subjected to the most difficult grinding operations include wheels such as cut-off wheels, billet snagging wheels and foundry snagging wheels used respectively for cutting steel, preparing steel billets for rolling and the like and for foundry snagging operations. Most of such )wheels are made up of abrasive grains bonded with ncvolak resin based bond having a hexamethylenetetramine hardening agent in the bond to produce a heat hardenable bond with good durability. The amount of hardening agent used is known to have a direct bearing on the durability of the cured wheel structure S
since the crosslinking density of the wheel is varied by the use of more or less of this agent.
However, heretofore durability has not been related to the amount of furfural coincidentally with the level of hexamethylenetetramine in the novolak resin.
It has now been found that the grinding ratio of a wheel, that is the amount of metal that can be ground away from the work per unit volume of the wheel consumed in the grinding oper-ation, can be maximized for any given phenolic resin bond by using an optimum amount of furfural for wetting the grain to be mixed with the phenolic resin bond in proportion to the hexamethylene-tetramine hardening agent present in the resinbond composition. While wetting of the grain with furfural prior to mixing the grain with a bond including a powdered novolak resin and possibly fillers, has been used in the past, the proportion of wetting agent applied to the grain has not been shown to be related in any way to the amount of hardening agent used in the phenolic resin bond composition. More particularly, it has not been known heretofore that the grinding ratio of he cured wheel can be controlled by varying the furfural wetting agent used on the grain in an amount that is relative to the amount of hexa-methylenetetramine hardening agent in the novolak resin bond.
Referring to the data set forth in the drawing, it can be seen that when furfural is used as a wetting agent for the abrasive grains in grinding wheels bonded with novolak resin con-taining hexamethylenetetramine as the hardening agent, the best grinding ratios in the cured wheels can be consistently realized by using an amount 11'7~ i5 of hexamethylenetetramine hardening agent in the range of from 9% to 14% in the phenolic resin bond mix and using from 20 to 60 cubic centimeters of furfural per pound of phenolic resin to wet the grains prior to mixing with the powdered resin bond composition. In the Figure, it is seen that as the quantity of furfural is increased in proportion to the increase in the quantity of hexamethylenetetramine in the novolak bond composition, that the grinding ratio is optimized in the resulting wheels. For each percentage of hardening agent in the resin bond composition within the 9% to 14% range, there is an optimum amount of furfural that should be used for wetting the grains prior to mixing wi~h that powdered resin bond in order to maximize the grinding ratio for the cured grinding wheel having that particular phenolic bond composition. In following this j invention, a phenolic resin bond can be formulated ~¦
for use with a given batch o~ abrasive grains to produce the desired durability in a wheel by using more or less of the hexamethylenetetramine hardening agent and a corresponding specific amount of furfural to produce optimum grinding properties in the finished grinding wheel.
For comparison, a pair of snagging wheels were made to demonstrate the advantage of relating the amount of wetting agent to the curing agent used. The steel conditioning snagging wheels were made with 16 grit alumina-zirconia abrasive grain and were bonded with a conventionally used phenolic resin bond to produce very dense wheels.
The grain in each wheel was wetted with furfural prior to mixing with the powdered novolak resin formulation containing 14% hexamethylenetetramine i ~l~f 8~)65 hardening agent. In one wheel the furfural level was 17 cubic centimeters per pound of resin in the wheel and in the other wheel, the furfural level was 40 cubic centimeters per pound of resin.
The wheels were hot pressed and cured in a convention-al manner to produce wheels 16 inches in diameter,
The invention relates to organic polymer bonded grinding wheels. More specifically the invention is concerned with grinding wheels bonded with hexamethylenetetramine cured phenolic resin used for example as snagging wheels and cut-off wheels.
BACKGROUND ART - `
PRIOR ART STATEMENT
10The following patents are representative of the most relevant prior art known to the Applicants at the time of filing of the application:
UNITED STATES PATENTS
3,406,020 October 15, 1968 W. J. D'Alessandro 15FORElGN PATENTS
1,207,766 October 7, 1970 ~nited Kingdom In the manufacture of resin bonded grinding wheels, a measured amount of abrasive grain is mixed with a powdered phenolic resin based bonding composition, then the resulting mix is pressed to form a wheel shape and the resin is cured. To promote - a better pickup and bonding of the resin to the 11'71~65 abrasive grains, it has been found useful to wet the grains with furfural prior to mixing the grain with the resin bond composition. The U. S. Patent 3,406,020 to D'Alessandro, ~ctober 15, 1968 and British Patent to Norton Company, 1,207,766, published October 7, 1970, describe such a wheel making procedure.
D'Alessandro teaches the making of phenolic bonded abrasive wheels having various additives mixed with the grain and bond composition that are alleged to produce a bonded wheel having an enhanced flexural strength. Various kinds of abrasive grains such as alumina, corundum, silicon carbide and diamond grains are mentioned for inclusion in the wheel bonded with a novolak resin with hexamethylenetetramine hardening agent. The harden-ing agent is used within a range of about 2~ to 50% based on the weight of the novolak, the preferred range being from about 3~ to 20% and more particularly 7% to 15%. This patent describes the use of from 0 to about 100 parts of a wetting agent per hundred parts of novolak, the wetting agent being selected from a group consisting of liquid resole resin, cresol, furfural and furfural alcohol. The wetting agent is blended with the abrasive grain in proportions of about 40 parts liquid phenolic resin wetting agent to 80 parts powdered novolak binder and in another formulation of 10 to 20 parts furfural with 120 parts of solid novolak resin. The formu-30 lation is controlled so that the abrasive mixof grains, wetting agent and resin binder are free flowing at room temperature and the only criterion for determining how much wetting agent to use is that the mix should remain relatively 35 free flowing up to the time it is charged into the mold.
11~7~6~;
The British patent is concerned with the making of an improved self-dressing manually controlled foundry snagging wheel having a resin bond, the wheel having from 22% to 26% pores by volume and the abrasive being spinel or mullite grains or mixtures of such abrasive grits. The making of wheels of such porosity is described and in the preparation of the abrasive grain and resin bond from which the wheel is molded, with reference to the use of furfural, there is only one comment and it is said that furfural is used in a conventional manner as a plasticiser in an amount of 55 cubic centimeters per pound of dry resin bond. No mention is made of the amount of hexamethylenetetramine employed.
DISCLOSURE OF THE INVENTION
The present invention provides an improve-ment over the prior art with the disclosure of a relationship between the amount of furfural wetting agent used on the grain in relation to the amount of curing agent used in the resin bond.
Whenever the term "mix" is used herein it is meant to have that meaning well known in the grinding wheel art viz. a more or less granular mixture of abrasive grain coated with a powdered uncured polymer or resin. Similarly, when the terms "bond" or "resin bond" are used, these terms are intended to include bond made up of resin alone and those which contain one or more of the many fillers, grinding aids, and reinforcing media know in the art. It has been discovered tha~
the maximum grinding ratio for any given wheel specification can be more assuredly attained when a preferred quantity of furfural wStting agent is 11~7~ 5 applied to the grain prior to the mixing of the grain with the powdered phenolic resin bond.
The furfural is used to wet the grain and is added to the grain in a certain proportion with respect to the hexamethylenetetramine curing agent used, which itself is added in a particular quantity to the resin bond to control the durability character-istic of the cured wheel.
It is known that the durability of a phenolic bonded grinding wheel such as a snagging wheel or cut-off wheel can be improved by increasing the crosslink density of the phenolic resin bond - which is accomplished by increasing the amount of hexamethylenetetramine hardening agent used with the novolak resin. It has now been found that there is a unique relationship between the amount of ~urfural wetting agent applied to the grain in relation to the quantity of hardening agent used in the novolak resin bond composition, the quantity of wetting agent being varied in the manner taught herein in order to control the grinding ratio characteristic in the cured wheel.
It is therefore an object of this invention to provide a grinding wheel with improved durability and grinding ratio characteristics.
Another object is to provide a mixing procedure for relating the amount of furfural used to wet the grain to the amount of hexamethylene-tetramine hardening agent in the bond in order to produce a grinding wheel having an improved durability and grinding ratio.
Another object of this invention is to teach how snagging and cut-off wheels and the like may be produced to have a maximum grinding ratio for their respective specific compositions.
, 1~7~65 -4a-Thus, in accordance with the present teachings, a phenolic resin bonded grinding wheel is provided in which the hexa-methylenetetramine is the curing agent and furfural is the wet-ting~agent applied, at least in part, to the abrasive grain in the preparation of the wheel mix. The furfural is employed in an amount of from 20-60 cm3 per pound of resin with the furfural being incorporated in the wheel formulation in an in-creasing amount as the amou~t of hexamethylenetetramine curing agent in the resin increases from 12~ to 20% by weight.
In accordance with a further teaching, a method is provided of approving the grinding ratio and durability of a resin bonded abrasive grinding wheel where the abrasive grain is wetted with furfural before the grain is mixed with the powdered novolak resin which has a hexamethylenetetramine hardening agent therein.
The method provided comprises wetting the grain with furfural, then mixing the furfural wetted grain with a powdered novolak resin bond with the hexamethylenetetramine hardener therein, measuring out a total quantity of furfural in an amount related to the quantity of hexamethylenetetramine in the resin bond, the amount falling within the range of from 20-60cc of furfural per pound of resin when the hardening agent is present in from 12%
to 20% by weight of the resin mix.
~t~8~6S
Other objects will appear in the specifi-cation below.
BRIEF DESCRIPTION OF THE DRAWINGS
The figure is a chart showing the variation of the grinding ratio of the finished abrasive wheels made in accordance with this invention by varying additions of furfural wetting agent added to the grain in relation to the quantity of hexamethylenetetramine hardening agent in the resin.
THE PREFERRED EMBODIMENTS
While the following discussion of the preferred embodiments is directed specifically at novolak resin i.e. phenol-formaldehyde condensate, it should be understood that other phenolic based polymers are within the scope of the invention e.g. modified phenol-formaldehyde resins, phenol-furfural resins and the like. The term "phenolic resin" as used herein, is intended to include such hexamethylenetetramine curable resins.
Conventional resin bonded grinding wheels that are subjected to the most difficult grinding operations include wheels such as cut-off wheels, billet snagging wheels and foundry snagging wheels used respectively for cutting steel, preparing steel billets for rolling and the like and for foundry snagging operations. Most of such )wheels are made up of abrasive grains bonded with ncvolak resin based bond having a hexamethylenetetramine hardening agent in the bond to produce a heat hardenable bond with good durability. The amount of hardening agent used is known to have a direct bearing on the durability of the cured wheel structure S
since the crosslinking density of the wheel is varied by the use of more or less of this agent.
However, heretofore durability has not been related to the amount of furfural coincidentally with the level of hexamethylenetetramine in the novolak resin.
It has now been found that the grinding ratio of a wheel, that is the amount of metal that can be ground away from the work per unit volume of the wheel consumed in the grinding oper-ation, can be maximized for any given phenolic resin bond by using an optimum amount of furfural for wetting the grain to be mixed with the phenolic resin bond in proportion to the hexamethylene-tetramine hardening agent present in the resinbond composition. While wetting of the grain with furfural prior to mixing the grain with a bond including a powdered novolak resin and possibly fillers, has been used in the past, the proportion of wetting agent applied to the grain has not been shown to be related in any way to the amount of hardening agent used in the phenolic resin bond composition. More particularly, it has not been known heretofore that the grinding ratio of he cured wheel can be controlled by varying the furfural wetting agent used on the grain in an amount that is relative to the amount of hexa-methylenetetramine hardening agent in the novolak resin bond.
Referring to the data set forth in the drawing, it can be seen that when furfural is used as a wetting agent for the abrasive grains in grinding wheels bonded with novolak resin con-taining hexamethylenetetramine as the hardening agent, the best grinding ratios in the cured wheels can be consistently realized by using an amount 11'7~ i5 of hexamethylenetetramine hardening agent in the range of from 9% to 14% in the phenolic resin bond mix and using from 20 to 60 cubic centimeters of furfural per pound of phenolic resin to wet the grains prior to mixing with the powdered resin bond composition. In the Figure, it is seen that as the quantity of furfural is increased in proportion to the increase in the quantity of hexamethylenetetramine in the novolak bond composition, that the grinding ratio is optimized in the resulting wheels. For each percentage of hardening agent in the resin bond composition within the 9% to 14% range, there is an optimum amount of furfural that should be used for wetting the grains prior to mixing wi~h that powdered resin bond in order to maximize the grinding ratio for the cured grinding wheel having that particular phenolic bond composition. In following this j invention, a phenolic resin bond can be formulated ~¦
for use with a given batch o~ abrasive grains to produce the desired durability in a wheel by using more or less of the hexamethylenetetramine hardening agent and a corresponding specific amount of furfural to produce optimum grinding properties in the finished grinding wheel.
For comparison, a pair of snagging wheels were made to demonstrate the advantage of relating the amount of wetting agent to the curing agent used. The steel conditioning snagging wheels were made with 16 grit alumina-zirconia abrasive grain and were bonded with a conventionally used phenolic resin bond to produce very dense wheels.
The grain in each wheel was wetted with furfural prior to mixing with the powdered novolak resin formulation containing 14% hexamethylenetetramine i ~l~f 8~)65 hardening agent. In one wheel the furfural level was 17 cubic centimeters per pound of resin in the wheel and in the other wheel, the furfural level was 40 cubic centimeters per pound of resin.
The wheels were hot pressed and cured in a convention-al manner to produce wheels 16 inches in diameter,
2 inches thick with a 6-inch hole in the center.
The wheels were both mounted on a 30 horsepower snagging machine and operated with a head force of 400 pounds at a speed of 9500 surface feet per minute. The wheels were used to grind a low alloy steel, AISI4140. The rate of wheel wear in cubic inches/hour and metal removal in pounds/hour was measured along with the power required to drive each wheel during the test. The comparative grinding results were recorded as follows:
a) the wheel made from grain wetted with 17cc per pound of resin mix prior to mixing, showed wheel wear at a rate of 25.51 cubic inches per hour, the metal was removed at a rate of 116.6 pounds/hour, at 20.40 kilowatts, giving a grinding ratio of 4.57.
b) the wheel identical with the wheel made with 17cc except that the grains were wetted with 40cc of furfural showed wheel wear at a rate of 20.82 cubic inches/hour, the metal was removed at a rate of 111.13 pounds/hour, with 18.88 kilowatts giving the more efficient grinding ratio of 5.34.
These results show an improved grinding ratio for the 40cc wheel as should be expected from observing the 14% hexamethylenetetramine curve in the figure. Approximately the same amount of metal was removed in each test, but with less 35 power being required with the 40cc wheel.
g With some grinding wheel formulations, high amounts of furfural cannot be added to the abrasive grain during the mix preparation or a mix results which is difficult or impossible to handle. To overcome this problem, some of the total amount of furfural is added directly to the abrasive grain and the remainder is added, alone or admixed with a second liquid, to the mix after the bond has been added to the abrasive.
The following is an example of this type of wheel specification.
In a second test hot pressed cut-off wheels were made with a novolak resin bond having a 9% hexamethylenetetramine hardening agent therein.
Two wheels were made with 24 grit alumina abrasive grits, each wheel having a 24-inch diameter, was
The wheels were both mounted on a 30 horsepower snagging machine and operated with a head force of 400 pounds at a speed of 9500 surface feet per minute. The wheels were used to grind a low alloy steel, AISI4140. The rate of wheel wear in cubic inches/hour and metal removal in pounds/hour was measured along with the power required to drive each wheel during the test. The comparative grinding results were recorded as follows:
a) the wheel made from grain wetted with 17cc per pound of resin mix prior to mixing, showed wheel wear at a rate of 25.51 cubic inches per hour, the metal was removed at a rate of 116.6 pounds/hour, at 20.40 kilowatts, giving a grinding ratio of 4.57.
b) the wheel identical with the wheel made with 17cc except that the grains were wetted with 40cc of furfural showed wheel wear at a rate of 20.82 cubic inches/hour, the metal was removed at a rate of 111.13 pounds/hour, with 18.88 kilowatts giving the more efficient grinding ratio of 5.34.
These results show an improved grinding ratio for the 40cc wheel as should be expected from observing the 14% hexamethylenetetramine curve in the figure. Approximately the same amount of metal was removed in each test, but with less 35 power being required with the 40cc wheel.
g With some grinding wheel formulations, high amounts of furfural cannot be added to the abrasive grain during the mix preparation or a mix results which is difficult or impossible to handle. To overcome this problem, some of the total amount of furfural is added directly to the abrasive grain and the remainder is added, alone or admixed with a second liquid, to the mix after the bond has been added to the abrasive.
The following is an example of this type of wheel specification.
In a second test hot pressed cut-off wheels were made with a novolak resin bond having a 9% hexamethylenetetramine hardening agent therein.
Two wheels were made with 24 grit alumina abrasive grits, each wheel having a 24-inch diameter, was
3/16 inch thick and had a 1-3/4 inch center hole.
In one wheel 15 cubic centimeters of furfural was used to wet the grains prior to mixing with the powdered resin bond followed by an additio~
of furfural to the resin-abrasive mix to bring the total furfural to 55.9cc per pound of resin.
In fabricating the other wheel in the same manner, 30cc of furfural was added directly to the abrasive grain, with a second quantity of furfural added to the resin-abrasive mix to bring the total furfural to 70cc per pound of resin.
Several tests were made with the resulting wheels. A dry cutting Tabor Hydraulic Chop machine was used to drive the wheels at 2200 RPM. Round bars of 304 stainless steel 2" in diameter were cut requiring six seconds for each cut. The data shows that the wheels made with grains wetted with 59.9cc of furfural per pound of resin had an average grinding ratio of 3.21 and the wheels il~71~ 5 made with grains wetted with 70.9cc of furfural had an average gr;nding ratio of 2.50 as would be expected from inspecting the 9% curve in Figure.
Another test was run with these cut-off wheels on a grinder to produce a plunge cutusing 20 kilowatts of power to drive a Fox swing frame grinder. A plunge cut of 2 inches was made on C1018CR steel. This machine was run at 1900 RPM. During this test, the wheel made with the 59.9cc of furfural had a grinding ratio of 0.99 and the wheel made with 70.9cc of furfural had a grinding ratio of 0.86.
These tests confirm that when the same power is applied to the different cut-off wheels made with different amounts of furfural in pro-portion to the hexamethylenetetramine curing agent present, a higher grinding ratio results when the preferred lower amount of furfural is used in a 9% hexamethylenetetramine bond, confirming the furfural relationship.
In the laboratory several different tests can be made under controlled conditions to compare the relative strength of cured resin bonded grinding wheel compositions. For these tests, bars having the same abrasive grits and resin bond composition therein as are used in a standard wheel composition, are molded and cured in the same manner as the snagging wheels described above. The flexural strength of each of the cured bars is measured by using a flexural span of 2~
with a 3 point bending flexural mode on an Instron test machine to determine the average breaking strength. This flexure test shows that the wheel strength is maintained even though furfural is varied to optimize grinding ratio while the dura-1~'7~iiS
bility is also increased, as is evident from thefollowing data.
A number of 5" x 1/2" x 1/4~ bars was made with 24 grit alumina-zirconia abrasive with a modified resin bond that included a carbosota wetting agent used with the powdered phenolic resin in an amount of about 20cc per pound of resin. In these bars the abrasive was bonded with novolak containing 9% and 14% addition of hexamethylenetetramine curing agent, with 17cc, 40cc and 60cc of furfural to wet the grain and the mix was:
Vol. ~ Wt. %
ZrO -Al 03-24 grit.54 71.9 Resin Bond _ 28.1 The resulting cured bars were tested to determine the average psi to break 4 bars at each furfural level. The average strength at the 17cc level was 14,490 psi, at 40cc level it was 15,400 and at the 60cc level it was 14,150.
This data shows that the wheel strength remains high with the addition of larger amounts of hexa-methylenetetramine hardening agent. The addition of furfural to the grain during mixing in proportion to the quantity of hexamethylenetetramine present preserves the strength of the bond as the hexamethyl-enetetramine content increases.
The recognition that the ideal amount of furfural addition to the grain is related to the quantity of hexamethylenetetramine hardening agent in the bond is important because it serves to improve the durability and grinding ratio of 1~7~65 modern grinding wheels which is desired because of the industry's intro~uction of new, higher powered steel conditioning grinders. When these heavier machines are operated at their full capacit~
for snagqing steel billets, for example, the most durable wheels are desired. Wheels more durable than those heretofore known are produced according to the present invention, by combining the proper quantities of furfural and hexamethylenetetramine.
In general it has been observed that certain combinations of the amount of a furfural wetting agent used with abrasive grains bonded with a novolak phenolic resin having a hexamethyl-enetetramine hardening agent in the bond to produce a grinding wheel, has an effect on the grinding ratio, durability and strength of the cured wheel.
When the hexamethylenetetramine levels are above 12~ by weîght in the resin and up to and including a 20% addition of this hardening agent, the furfural level should be varied proportionately from 20cc of furfural per pound of resin to wet the grain to as much as 60cc of furfural per pound of resin.
Wheels made in accordance with the teaching of this invention are otherwise produced with known techniques for mixing, use of additives such as - fillers, grinding aids and the like, hot or cold pressing and curing the phenolic resin mix to produce the desired wheel.
While the above describes the preferred form of this invention, it is possible that modifi-cations thereof ma~ occur to those skilled in the art that will fall within the scope of the following claims. It should be un~erstood that o~s the present invention is independent of the type of abrasive used and therefore encompasses abrasives such as fused and sintered alumina, fused and sintered alumina-zirconia, silicon carbide, spinel, flint, mullite, cubic boron nitride, boron carbide, diamond and the like, and mixtures thereof.
In one wheel 15 cubic centimeters of furfural was used to wet the grains prior to mixing with the powdered resin bond followed by an additio~
of furfural to the resin-abrasive mix to bring the total furfural to 55.9cc per pound of resin.
In fabricating the other wheel in the same manner, 30cc of furfural was added directly to the abrasive grain, with a second quantity of furfural added to the resin-abrasive mix to bring the total furfural to 70cc per pound of resin.
Several tests were made with the resulting wheels. A dry cutting Tabor Hydraulic Chop machine was used to drive the wheels at 2200 RPM. Round bars of 304 stainless steel 2" in diameter were cut requiring six seconds for each cut. The data shows that the wheels made with grains wetted with 59.9cc of furfural per pound of resin had an average grinding ratio of 3.21 and the wheels il~71~ 5 made with grains wetted with 70.9cc of furfural had an average gr;nding ratio of 2.50 as would be expected from inspecting the 9% curve in Figure.
Another test was run with these cut-off wheels on a grinder to produce a plunge cutusing 20 kilowatts of power to drive a Fox swing frame grinder. A plunge cut of 2 inches was made on C1018CR steel. This machine was run at 1900 RPM. During this test, the wheel made with the 59.9cc of furfural had a grinding ratio of 0.99 and the wheel made with 70.9cc of furfural had a grinding ratio of 0.86.
These tests confirm that when the same power is applied to the different cut-off wheels made with different amounts of furfural in pro-portion to the hexamethylenetetramine curing agent present, a higher grinding ratio results when the preferred lower amount of furfural is used in a 9% hexamethylenetetramine bond, confirming the furfural relationship.
In the laboratory several different tests can be made under controlled conditions to compare the relative strength of cured resin bonded grinding wheel compositions. For these tests, bars having the same abrasive grits and resin bond composition therein as are used in a standard wheel composition, are molded and cured in the same manner as the snagging wheels described above. The flexural strength of each of the cured bars is measured by using a flexural span of 2~
with a 3 point bending flexural mode on an Instron test machine to determine the average breaking strength. This flexure test shows that the wheel strength is maintained even though furfural is varied to optimize grinding ratio while the dura-1~'7~iiS
bility is also increased, as is evident from thefollowing data.
A number of 5" x 1/2" x 1/4~ bars was made with 24 grit alumina-zirconia abrasive with a modified resin bond that included a carbosota wetting agent used with the powdered phenolic resin in an amount of about 20cc per pound of resin. In these bars the abrasive was bonded with novolak containing 9% and 14% addition of hexamethylenetetramine curing agent, with 17cc, 40cc and 60cc of furfural to wet the grain and the mix was:
Vol. ~ Wt. %
ZrO -Al 03-24 grit.54 71.9 Resin Bond _ 28.1 The resulting cured bars were tested to determine the average psi to break 4 bars at each furfural level. The average strength at the 17cc level was 14,490 psi, at 40cc level it was 15,400 and at the 60cc level it was 14,150.
This data shows that the wheel strength remains high with the addition of larger amounts of hexa-methylenetetramine hardening agent. The addition of furfural to the grain during mixing in proportion to the quantity of hexamethylenetetramine present preserves the strength of the bond as the hexamethyl-enetetramine content increases.
The recognition that the ideal amount of furfural addition to the grain is related to the quantity of hexamethylenetetramine hardening agent in the bond is important because it serves to improve the durability and grinding ratio of 1~7~65 modern grinding wheels which is desired because of the industry's intro~uction of new, higher powered steel conditioning grinders. When these heavier machines are operated at their full capacit~
for snagqing steel billets, for example, the most durable wheels are desired. Wheels more durable than those heretofore known are produced according to the present invention, by combining the proper quantities of furfural and hexamethylenetetramine.
In general it has been observed that certain combinations of the amount of a furfural wetting agent used with abrasive grains bonded with a novolak phenolic resin having a hexamethyl-enetetramine hardening agent in the bond to produce a grinding wheel, has an effect on the grinding ratio, durability and strength of the cured wheel.
When the hexamethylenetetramine levels are above 12~ by weîght in the resin and up to and including a 20% addition of this hardening agent, the furfural level should be varied proportionately from 20cc of furfural per pound of resin to wet the grain to as much as 60cc of furfural per pound of resin.
Wheels made in accordance with the teaching of this invention are otherwise produced with known techniques for mixing, use of additives such as - fillers, grinding aids and the like, hot or cold pressing and curing the phenolic resin mix to produce the desired wheel.
While the above describes the preferred form of this invention, it is possible that modifi-cations thereof ma~ occur to those skilled in the art that will fall within the scope of the following claims. It should be un~erstood that o~s the present invention is independent of the type of abrasive used and therefore encompasses abrasives such as fused and sintered alumina, fused and sintered alumina-zirconia, silicon carbide, spinel, flint, mullite, cubic boron nitride, boron carbide, diamond and the like, and mixtures thereof.
Claims (6)
1. A phenolic resin bonded grinding wheel in which hexamethylenetetramine is the curing agent and furfural is the wetting agent applied, at least in part, to the abrasive grain in the preparation of the wheel mix, said furfural being used in an amount of from 20 to 60 cubic centimeters per pound of resin, the furfural being incorporated in the wheel formulation in an increasing amount as the amount of hexamethylenetetramine curing agent in the resin increases from 12% to 20% by weight.
2. An abrasive mix for producing snagging and cut-off wheels wherein abrasive grains are bonded in a powdered phenolic resin bond having 12% to 20% by weight of hexamethylenetetramine hardening agent, comprising abrasive grain wetted with 20-60 cubic centimeters of furfural per pound of dry resin, said wetted grain being mixed with said powdered resin bond and wherein additional furfural may be added to said mix to bring the total quantity of furfural to an amount proportioned to the quantity of hexamethylene-tetramine hardening agent in the bond.
3. An abrasive mix as in Claim 1 wherein said hexamethylenetetramine is present in said resin in an amount of 14% by weight of said resin and said furfural is added in an amount of 40cc per pound of resin mix.
4. An abrasive mix in any of Claims 1 or 2 or 3 wherein said phenolic resin is a novolak resin.
5. A method of improving the grinding ratio and durability of a resin bonded abrasive grinding wheel wherein the abrasive grain is wetted with furfural before the grain is mixed with a powdered novolak resin having a hexamethylenetetramine hardening agent therein, comprising wetting the grain with furfural, then mixing the furfural wetted grain with a powdered novolak resin bond with the hexamethylenetetramine hardener therein, measuring out a total quantity of furfural in an amount related to the quantity of hexamethyl-enetetramine in the resin bond, said amount falling within a range of from 20 to 60cc of furfural per pound of resin when the hardening agent is present in from 12% to 20% by weight of said resin mix .
6. The method of claim 5 wherein a second quantity of furfural is added to the resin-abrasive mix prior to wetting the grain.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US17038280A | 1980-07-21 | 1980-07-21 | |
| US06/170,382 | 1980-07-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1178065A true CA1178065A (en) | 1984-11-20 |
Family
ID=22619654
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000375745A Expired CA1178065A (en) | 1980-07-21 | 1981-04-16 | Phenolic resin bonded grinding wheels |
Country Status (13)
| Country | Link |
|---|---|
| JP (1) | JPS5727667A (en) |
| AT (1) | AT375580B (en) |
| AU (1) | AU7284281A (en) |
| BR (1) | BR8104657A (en) |
| CA (1) | CA1178065A (en) |
| DE (1) | DE3126158C2 (en) |
| FR (1) | FR2486851B1 (en) |
| GB (1) | GB2080323B (en) |
| IN (1) | IN154439B (en) |
| IT (1) | IT1144410B (en) |
| NL (1) | NL8103379A (en) |
| SE (1) | SE453299B (en) |
| ZA (1) | ZA812872B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3414153A1 (en) * | 1984-04-14 | 1985-10-17 | Dynamit Nobel Ag, 5210 Troisdorf | Process for the production of refractory bricks or other shaped articles |
| DE3705540A1 (en) * | 1986-06-13 | 1987-12-17 | Ruetgerswerke Ag | HIGH TEMPERATURE RESISTANT MOLDS |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB225436A (en) * | 1924-03-06 | 1924-12-04 | Carborundum Co | Improved manufacture of abrasive devices |
| US2793105A (en) * | 1954-08-06 | 1957-05-21 | Monsanto Chemicals | Grinding wheels |
| US3208836A (en) * | 1960-09-09 | 1965-09-28 | Borden Co | Cold press method of making abrasive articles |
| US3406020A (en) * | 1964-09-04 | 1968-10-15 | Union Carbide Corp | Abrasive wheels comprising a novolak resin and a thermoplastic polyhydroxyether |
| GB1523935A (en) * | 1975-08-04 | 1978-09-06 | Norton Co | Resinoid bonded abrasive products |
-
1981
- 1981-04-16 CA CA000375745A patent/CA1178065A/en not_active Expired
- 1981-04-30 ZA ZA00812872A patent/ZA812872B/en unknown
- 1981-05-29 JP JP8125081A patent/JPS5727667A/en active Granted
- 1981-06-26 FR FR8112584A patent/FR2486851B1/en not_active Expired
- 1981-07-02 DE DE3126158A patent/DE3126158C2/en not_active Expired
- 1981-07-10 SE SE8104307A patent/SE453299B/en not_active IP Right Cessation
- 1981-07-13 IN IN781/CAL/81A patent/IN154439B/en unknown
- 1981-07-14 GB GB8121679A patent/GB2080323B/en not_active Expired
- 1981-07-14 AU AU72842/81A patent/AU7284281A/en not_active Abandoned
- 1981-07-16 NL NL8103379A patent/NL8103379A/en not_active Application Discontinuation
- 1981-07-20 AT AT0320181A patent/AT375580B/en not_active IP Right Cessation
- 1981-07-20 BR BR8104657A patent/BR8104657A/en unknown
- 1981-07-20 IT IT68008/81A patent/IT1144410B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| AU7284281A (en) | 1982-01-28 |
| JPH0122116B2 (en) | 1989-04-25 |
| BR8104657A (en) | 1982-04-06 |
| DE3126158A1 (en) | 1982-03-11 |
| ZA812872B (en) | 1982-05-26 |
| IN154439B (en) | 1984-10-27 |
| FR2486851A1 (en) | 1982-01-22 |
| JPS5727667A (en) | 1982-02-15 |
| FR2486851B1 (en) | 1987-10-16 |
| AT375580B (en) | 1984-08-27 |
| IT1144410B (en) | 1986-10-29 |
| GB2080323A (en) | 1982-02-03 |
| ATA320181A (en) | 1984-01-15 |
| SE453299B (en) | 1988-01-25 |
| IT8168008A0 (en) | 1981-07-20 |
| DE3126158C2 (en) | 1984-08-30 |
| NL8103379A (en) | 1982-02-16 |
| SE8104307L (en) | 1982-01-22 |
| GB2080323B (en) | 1984-10-31 |
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| MKEX | Expiry |