EP0941373B1 - Procede permettant d'obtenir des rayons d'arrondis bien definis par polissage electrolytique - Google Patents

Procede permettant d'obtenir des rayons d'arrondis bien definis par polissage electrolytique Download PDF

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Publication number
EP0941373B1
EP0941373B1 EP97927531A EP97927531A EP0941373B1 EP 0941373 B1 EP0941373 B1 EP 0941373B1 EP 97927531 A EP97927531 A EP 97927531A EP 97927531 A EP97927531 A EP 97927531A EP 0941373 B1 EP0941373 B1 EP 0941373B1
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EP
European Patent Office
Prior art keywords
inserts
electrolyte
surface finish
high surface
edge
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 - Lifetime
Application number
EP97927531A
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German (de)
English (en)
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EP0941373A1 (fr
Inventor
Hans Johansson
Ulf Rolander
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sandvik AB
Original Assignee
Sandvik AB
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Publication date
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F3/00—Electrolytic etching or polishing
    • C25F3/16—Polishing
    • C25F3/22—Polishing of heavy metals
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F3/00—Electrolytic etching or polishing
    • C25F3/16—Polishing

Definitions

  • the present invention relates to a method for obtaining well defined edge radii on cutting tool inserts in combination with a high surface finish over the whole insert by electropolishing technique.
  • Inserts for chip forming machining made of cemented carbide or of titanium based carbonitride (cermet) consist of at least one main cutting edge and a connecting nose (corner).
  • Such inserts are produced by the powder metallurgical methods of milling of powders of the hard constituents and binder phase, pressing to bodies of desired shape and finally sintering the pressed bodies.
  • the pressing is generally done as tool pressing between two opposing punches in a die.
  • the inserts obtain rather sharp edges.
  • the insert edges because of the small gap, a few microns wide, that always exists between the punches and the die wall the insert edges also have burr. Such edges break too easily when used.
  • the inserts are subjected to an edge rounding operation including methods such as lapping, tumbling, brushing or blasting. These operations, however, are difficult to control with any desirable accuracy. For this reason, the edge rounding values usually range between 30 and 75 ⁇ m on cemented carbide inserts for a majority of machining applications. Smaller edge rounding values are generally not possible to obtain with mechanical methods. Also, the edges often obtain defects in the initial stage of the mechanical operation. These defects disappear during the continued treatment provided that the final edge rounding obtained is larger than the defect size.
  • edge rounding means lower cutting forces.
  • the choice of edge rounding is a compromise between desired edge strength and acceptable cutting forces.
  • For certain cutting operations such as threading and machining of heat resistant materials, aluminium or cast iron, lower cutting forces are desirable.
  • the above mentioned methods for edge rounding are generally not useful at least on a large, industrial scale.
  • Electrolytic smoothing or deburring is a commonly employed technique. Two well-known processes are called electrochemical deburring and electropolishing.
  • US 4,405,422 discloses methods for electrolytic deburring of copper or copper alloys and 4,411,751 of steel or aluminium alloys.
  • the binder phase is often dissolved first, resulting in a porous surface layer with reduced strength and often containing portions comprising several grains that have disappeared, so called pitting. It is therefore essential that an electrolyte is used which provides an even removal of material, essentially without depth effect.
  • An example of this is US 5,380,408 which discloses a method for removing cobalt from the surface of cemented carbide using an electrolyte of sulphuric and phosphoric acids. This method, however, does not generate edge rounding.
  • Fig. 1 shows in 5X the clearance face of an insert treated according to prior art.
  • Fig. 2 shows in 5X the clearance face of an insert treated according to the invention.
  • Fig. 3 shows in 500X an edge of an insert with burr.
  • Fig. 4 shows in 500X an edge after rounding according to the invention.
  • the inserts are thoroughly cleaned e.g. by ultrasonic cleaning in methanol so that dust, loose particles, grease stains etc. that may affect the polishing result are removed from the surfaces.
  • the inserts are then submerged in the electrolytic bath and a voltage is applied between the inserts (anode) and a cathode. Strong agitation is carried out in order to obtain stable conditions with electrolyte flowing along all sides of the inserts.
  • the cathode should be made of an acid resistant material, e.g. platinum or acid resistant stainless steel, and have a surface area comparable to or preferably larger than the total surface area of the inserts.
  • the electrolyte shall contain >15 but ⁇ 50 vol%, preferably 20-30 vol% perchloric (HClO 4 ) or sulphuric (H 2 SO 4 ) acid, or a mixture thereof, in methanol.
  • Methanol may be partly or fully substituted by more viscous fluids, e.g. another lower alcohol such as butanol, glycerol or ethyleneglycol-monobutylether, in order to decrease the polishing speed or as a means for obtaining more stable conditions.
  • the temperature of the electrolyte may be varied between room temperature and -60 °C, mainly in order to change the viscosity of the electrolyte.
  • the voltage shall be lower than 50 V but higher than 3 V, preferably 10-30 V. Generally a DC-voltage is used. But it is also possible to use pulsed or AC-voltage. The proper choice of voltage depends on the design of the equipment used, the degree of agitation obtained and the choice of electrolyte and temperature.
  • the inserts are rinsed, e.g. in methanol, in order to avoid corrosion caused by the electrolyte.
  • the method is suitable for mass production since large quantities of inserts can be polished simultaneously with high polishing speed.
  • the accuracy and reproducibility is extremely high.
  • Edge defects due to pressing or grinding will decrease in size or even vanish depending on the size relation between defect and final edge radius.
  • the material removal rate is substantially larger along the edges than on the flat surfaces of the insert.
  • the method can be used also for gradient sintered grades, i.e. grades with a binder phase enriched surface layer, without risking that the gradient is removed.
  • a commercially available cemented carbide insert (SANDVIK H10F) with as-sintered sharp edges with remaining burr was electropolished for 6 minutes using an electrolyte consisting of 22 vol% sulphuric acid in methanol, cooled to -50 °C, and a DC-voltage of 20 volts.
  • a 30 cm 2 platinum sheet was used as cathode and the electrolyte was stirred strongly using a magnetic mixer. Smooth rounded edges were obtained with small edge radii about 20 ⁇ m and excellent surface finish.
  • Fig. 1 a clearance face is shown from the insert treated as disclosed in US 5,591,320 and in Fig. 2 treated according to the invention.
  • Fig. 3 shows an edge with remaining burr and Fig. 4 after treatment according to the invention.
  • Example 1 was repeated but with a shorter polishing time of 4 minutes. Smooth rounded edges were obtained with small edge radii about 10 ⁇ m and excellent surface finish.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
  • Cutting Tools, Boring Holders, And Turrets (AREA)
  • ing And Chemical Polishing (AREA)

Claims (2)

  1. Procédé d'obtention d'arrondis d'arêtes d'éléments rapportés ou inserts pour outils de coupe conjointement avec une grande qualité d'état de surface sur tout l'élément rapporté en carbure cémenté ou en alliages de carbonitrure à base de titane, caractérisé par les étapes suivantes :
    obtention d'un électrolyte contenant plus de 15% à 50% en volume d'acide perchlorique (HClO4) ou d'acide sulfurique (H2SO4) ou un mélange de ceux-ci, dans le méthanol ou dans un autre liquide organique support
    immersion desdits éléments rapportés dans l'électrolyte
    mise en place d'une électrode constituée d'un matériau résistant à l'acide, par exemple en platine ou en acier inoxydable résistant à l'acide au sein de l'éléctrolyte
    application d'un potentiel électrique entre les éléments rapportés (anode) et l'électrode (cathode) pendant une durée suffisante pour arrondir les arêtes desdits éléments rapportés à un degré voulu tout en conférant aussi une excellente qualité de l'état de surface sur l'ensemble des éléments rapportés.
  2. Procédé selon la revendication précédente, caractérisé en ce que l'on obtient un arrondi d'arête d'environ 10 µm conjointement à une grande qualité de l'état de surface.
EP97927531A 1996-06-07 1997-05-22 Procede permettant d'obtenir des rayons d'arrondis bien definis par polissage electrolytique Expired - Lifetime EP0941373B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE9602278 1996-06-07
SE9602278A SE511208C2 (sv) 1996-06-07 1996-06-07 Sätt att erhålla väldefinierade eggradier på verktygsskär och hög ytfinhet över hela skäret genom elektropolering
PCT/SE1997/000840 WO1997046741A1 (fr) 1996-06-07 1997-05-22 Procede permettant d'obtenir des rayons d'arrondis bien definis par polissage electrolytique

Publications (2)

Publication Number Publication Date
EP0941373A1 EP0941373A1 (fr) 1999-09-15
EP0941373B1 true EP0941373B1 (fr) 2001-09-05

Family

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EP97927531A Expired - Lifetime EP0941373B1 (fr) 1996-06-07 1997-05-22 Procede permettant d'obtenir des rayons d'arrondis bien definis par polissage electrolytique

Country Status (6)

Country Link
EP (1) EP0941373B1 (fr)
JP (1) JP2000514866A (fr)
AT (1) ATE205265T1 (fr)
DE (1) DE69706558T2 (fr)
SE (1) SE511208C2 (fr)
WO (1) WO1997046741A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102230210A (zh) * 2011-06-08 2011-11-02 中南大学 一种不锈钢无铬电解抛光液及其表面抛光处理工艺

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996018759A1 (fr) * 1994-12-12 1996-06-20 Sandvik Ab Technique d'electropolissage permettant la realisation d'aretes arrondies bien definies sur des plaquettes amovibles d'outils de coupe

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3357905A (en) * 1960-03-28 1967-12-12 Cleveland Twist Drill Co Electrolyte composition and method of electrolytically removing stock from workpiece
WO1991004353A1 (fr) * 1989-09-22 1991-04-04 Showa Denko Kabushiki Kaisha Procede de synthese de diamant depose en phase vapeur sur un substrat traite par voie electrochimique

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996018759A1 (fr) * 1994-12-12 1996-06-20 Sandvik Ab Technique d'electropolissage permettant la realisation d'aretes arrondies bien definies sur des plaquettes amovibles d'outils de coupe

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102230210A (zh) * 2011-06-08 2011-11-02 中南大学 一种不锈钢无铬电解抛光液及其表面抛光处理工艺
CN102230210B (zh) * 2011-06-08 2013-12-11 中南大学 一种不锈钢无铬电解抛光液及其表面抛光处理工艺

Also Published As

Publication number Publication date
WO1997046741A1 (fr) 1997-12-11
JP2000514866A (ja) 2000-11-07
SE511208C2 (sv) 1999-08-23
SE9602278L (sv) 1997-12-08
DE69706558T2 (de) 2002-04-18
SE9602278D0 (sv) 1996-06-07
EP0941373A1 (fr) 1999-09-15
ATE205265T1 (de) 2001-09-15
DE69706558D1 (de) 2001-10-11

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