Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16N—LUBRICATING
  • F16N1/00—Constructional modifications of parts of machines or apparatus for the purpose of lubrication
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
  • F16C33/02—Parts of sliding-contact bearings
  • F16C33/04—Brasses; Bushes; Linings
  • F16C33/06—Sliding surface mainly made of metal
  • F16C33/10—Construction relative to lubrication

Definitions

• Lubricating oil is reliably con-fined to a workpiece portion by means of a barrier consisting of an oil repelling layer coated on the workpiece around said portion thereof. Firstly, the whole workpiece is coated with the oil repelling layer. This layer is then removed from said portion by exposing the latter at a place where it will be hit by an electrical discharge which crosses the gap between two electrodes with a substantially constant intensity and without sparkling.
• This invention relates to antifrictional surface treatments for workpieces having some predetermined portion of their surface which is intended to be submitted to frictional engagements and has to be lubricated for that purpose.
• the invention relates more particularly to the methods of treating such workpieces in order that lubricating oil is reliably confined to the workpiece portion which has to remain lubricated and whereby an oil repelling barrier is formed on the workpiece around said portion.
• the oil repelling layer is not set over the whole workpiece surface, but only around the portion thereof, which is to be lubricated.
• the oil repelling layer constitutes a barrier around said portion of the workpiece surface and this barrier prevents the lubricant from spreading beyond the boundaries of the surface portion which is surrounded by the oil repelling layer.
• the antifrictional surface treatment comprises the step of exposing said portion of the workpiece at a place where it wil be hit by an electrical discharge which crosses the gap between two electrodes with a substantially constant intensity and without sparkling.
• the workpieces to be treated are either electrically conductive such as pieces of steel, brass, etc., or electrically nonconductive such as jewels of corundum.
• the workpiece to be treated by the method according to the invention is electrically conductive, it may constitute one of the two electrodes between which one produces the electrical discharge intended for removing the oil repelling layer from the workpiece portion which is to be lubricated.
• the electrical discharge used for treating the workpieces according to the invention must of course be absolutely free of sparkles. This result will be obtained if the circuit comprising the electrodes has an extremely small capacity.
• An electrical discharge can easily be produced without sparkling between two electrodes by connecting a high resistor to the circuit of the electrodes in the immediate vicinity of at least one of them.
• the shape and the sizes of the space crossed by the electrical discharge which is something like a glow discharge, can be modified within broad limits by modifying the shape of the electrodes, the distance between them and the bias thereof.
• the resistor, which is connected to the circuit of the electrodes, in the vicinity of at least one of them, is then increased until the discharge between the electrodes is free of sparkles.
• the other electrode can be made with such a shape and located at such a place relative to the workpiece that the electrical discharge will exactly hit that portion of the workpiece surface which is to be lubricated.
• An electrical discharge of the type indicated above has the property of destroying almost instaneously the oil repelling layer with which the workpiece surface were previously coated. Whichever may be the nature of the oil repelling layer and even if it consists of a strongly bound adsorbed coating, this layer is destroyed almost instantaneously on the workpiece portion which has been hit by the glow discharge.
• the workpieces to be treated can thus be placed on appropriate conveying means which cause them to travel one after the other either at constant speed or stepwise through a path which is adjusted in such manner relative to the fixed electrode or electrodes that the portion of these workpieces which is to be lubricated will move opposite said electrodes and cause thereby the electrical discharge to take place under such conditions that the right workpiece portion will be hit by that discharge.
• the workpieces can be moved at a constant speed by their conveying means even if they operate as electrodes, because the glow discharge instantaneously takes place between the fixed electrode and a workpiece as soon asthis workpiece moves opposite the fixed electrode.
• the oil repelling layer has to be destroyed on the wall of a bore of'an electrically nonconductive workpiece, such as for instance of a jewel pivot bearing for a watch or a measuring instrument
• two electrodes are provided on a common axis so that they can be reciprocated along that axis.
• the workpieces are then conveyed stepwise and one after the other between these electrodes.
• the electrodes are kept away from each other and there is no electrical discharge between them.
• the electrodes are moved toward each other until each one stands in the vicinity of one end of the workpiece bore and the glow discharge takes place.
• the oil-repelling layer can be destroyed either only on the wall of the bore, or in addition thereto, on both sides of the workpiece, in more or less broad circular areas concentric to said bore.
• the workpiece surface portion which is to be lubricated extends on two workpiece facets separated from each other by an edge, as for instance with the resting face and the impulse face on the pallets of an escapement lever for watches, it can be observed, in particular ifs'aid edge is sharp, that the barrier constituted by the oil repelling layer does not prevent the lubricant from leaving the workpiece portion on which it should remain. According to the operation of the workpiece, the whole lubricant can indeed be brought mechanically from one of said workpiece facets onto the other one. With an escapement lever, the oil is brought by the teeth of the escape Wheel from the resting faces of the lever pallets onto the impulse faces thereof.
• a sharp edge between said facets constitutes an even stronger oil barrier than the oil repelling layer. If the lubricant amount thus brought onto said second facet is larger than the capacity thereof, it can be observed that the lubricant forces the barrier which is constituted by the oil repelling layer and not that which is constituted by the sharp edge. A a consequence thereof, the lubricant does not flow back onto said first facet, but it spreads over workpiece portions where it is useless.
• the edge between the two workpiece facets which are to be lubricated need only be machined so as to form a surface of transition between these two facets.
• a surface of transition having a very small radius of curvature is already proper. Tests have shown that a surface of transition having a radius comprised between .015 and .10 mm. already enables the lubricant, which had been mechanically brought onto one of said two facets, to flow automatically'back over the edge onto the first facet so a to uniformly cover the whole workpiece surface portion surrounded by the oil repelling layer.
• a surface of transition having a radius of curvature comprised between the above-mentioned limits does no longer oppose any resistance to the lubricant so that the same can freely flow within the barrier constituted by the oil repelling layer, as if this barrier would extend onto one and the same facet of the workpiece.
• any mechanical method known to those skilled in the art can be resorted to.
• the rounded edge constituting the surface of transition must be tangent to either one of said two facets of the workpiece.
• the smoothness of the surface of the rounded edge must of course be the same as that of said two workpiece facets.
• the small sizes of the surface of transition which has to be provided between said two facets of the workpiece in order to ensure a free spreading of the lubricant over these two facets, permit the surface treatment according to the invention to be used even with workpieces, the operation of which requires a very precise shape, because said surface of transition does not modify the shape of the workpiece beyond an amount which is compatible with the operation, i.e.- beyond the usual tolerances.
• the surface of transition between said two workpiece facets is preferably formed before coating the workpiece with the oil repelling layer.
• the workpiece can be handled as a workpiece having no edge extending across or within its portion to be lubricated. Said workpiece can thus be coated over its whole surface with the oil repelling layer and then be moved opposite either one electrode, if it is electrically conductive and may constitute the other electrode, or between two electrodes, if it is electrically nonconductive.
• machining said edge be- 10 fore coating the workpiece with said oil repelling layer.
• ALFRED L. LEAVIIT Primary Examiner References Cited
• A. M. GRIMALDI Assistant Examiner UNITED STATES PATENTS CL 3,225,866 12/1965 Bernett et a1. 184-1 15 1 3.1

Applications Claiming Priority (2)

Publications (1)

Family

ID=25708703

Family Applications (1)

Country Status (3)

Cited By (2)

Families Citing this family (1)

• 1966
  • 1966-12-15 CH CH1791466A patent/CH467427A/fr unknown
• 1967
  • 1967-08-05 DE DE19671621653 patent/DE1621653A1/de active Pending
  • 1967-08-07 US US00658619A patent/US3711311A/en not_active Expired - Lifetime

Also Published As

Similar Documents

Legal Events