FR2475447A1 - Flash blasted from duroplastic component - using straight and helical air streams and crushed fruit stones - Google Patents

Abstract

A method of removing the flash from duroplastic components consists of projecting a rectilinear stream of solid particles by compressed air onto the surface of the components at sufficient kenetic energy to remove the flash without damaging the surface finish, and simultaneously projecting solid particles by a helical air stream which surrounds the rectilinear air stream. A nozzle for projecting the straight air stream additionally possesses a helical groove for generating the helical air stream. The depth of the groove is pref. 0.8-1.5mm. The preferred solid oarticles are granulated or broken down fruit kernals. Used in particular for duroplastic components for electrical and radio equipment. Also for the surface treatment of metallic and non-metallic components to remove encrustations, lacquer or paint stains.

Description

 The present invention relates to the treatment of the surface of parts and in particular relates to a method of deburring parts in particular of thermosetting materials.

 The invention can be applied with maximum efficiency to the production of parts made of thermosetting materials for electrical and radio equipment.

 In addition, the invention can be applied to the treatment of the surface of metal and non-set metal parts, to remove scale and paint or varnish coatings.

 A process is known for deburring parts made of thermosetting materials (United States patent NO 3,676,963, B24C 1/00 cl. 51-320, 1972), consisting of the following. A flow of hard particles moving in a straight line under the action of compressed air is made to act on the parts to be treated. As hard particles, ice particles are used. In this case the burrs are eliminated from that of the surfaces of the part which is arranged perpendicular to the flow of treatment agent.

 The application of this method does not make it possible to deburr the parts of thermosetting materials having several joint planes and arranged at different angles with respect to the flow of treatment agent.

 The action of the treatment agent flow is not even in all directions and is effected by ricochets, so its effect on the burrs is weakened and of random direction. As a result, the parts must be deburred in several stages.

 As a result, the processing time of the parts increases and the productivity of the work decreases.

 It has therefore been proposed to create a deburring process for parts made of thermosetting materials, in which the direction of the flow of particles relative to the part would be such as to ensure deburring of the part from all sides. simultaneously.

 The solution consists in a process for deburring parts made of thermosetting materials, according to which the parts are made to act, by means of compressed air, a rectilinear flow of hard particles endowed with sufficient kinetic energy to break and eliminate burrs. surfaces of the parts without altering the gloss of these surfaces, a process in which, according to the invention, an additional flow of hard particles is made to act on the parts enveloping the rectilinear flow and directed along a helix.

 Thanks to the presence of the additional flux enveloping the rectilinear flow and directed along a helix, the penetrating power of hard particles increases, because these particles arrive on the surfaces of the parts from various angles.

 The hard particles moving in a straight line and following a helix and acting on the parts to be treated from different angles retain in this case sufficient kinetic energy to break the burrs in the horizontal and vertical planes.

 In what follows, the invention is explained by the detailed description of a concrete but non-limiting example of embodiment, with reference to the single appended drawing which schematically represents the direction of the flow of solid particles relative to the parts to be treated.

 The process for deburring parts made of thermosetting materials, in accordance with the invention, is shown diagrammatically in the figure of the appended drawing.

 On a turntable 1 the parts 2 are fixed, burrs at the top, the burr 3 being in a horizontal plane, and the burrs 4 and 5, in vertical planes.

 The pieces 2 can be placed side by side without spacing if they have only burrs 4 and 5, or with spacing if they have only burrs 3 and 5.

 Parts made of thermosetting materials may other than parts of the carcass, base, plate, case type, made from molding powders and made of plastics reinforced with glass fibers. A nozzle 6, for example of the suction or ejector type, the mixer of which has on its inner surface helical grooves 7, delivers under the action of compressed air two streams of hard particles: a straight stream 8 (according to the arrow "a") and an additional flow 9 (along the arrow "b") enveloping the rectilinear flow 8 and directed along a helix.

 The rectilinear flow 8 (along arrow "a") of hard particles breaks and removes the burr 3 from the horizontal plane of the part 2; the additional flow 9 (along arrow "b") of hard particles, which strikes part 2 at acute angles, breaks and removes burrs 4 and 5 from the vertical planes of part 2.

 As hard particles, crushed fragments of cherry, plum, apricot, etc. stones or plastic balls are used.

Example 1.
The pieces of 40x40x20 mm, made of thermosetting material with the addition of a filler such as wood flour, and having burrs up to 0.2 mm thick in the vertical and horizontal planes, are placed on the surface of the turntable with a spacing of 15 to 20 mm from each other.

 The distance between the nozzle nose of the ejector nozzle and the surface of the parts is 160 n. The diameter of the suction nozzle channel is 12 n.

The depth of the helical grooves of the mixer is 0.8 to 1.0 mm.

 The hard particles used are crushed flakes of plum, apricot kernels, up to 1.5 mm thick.

 The speed of rotation of the plate is 4 rpm.

The operating pressure of the compressed air supplying the ejection nozzle is up to 0.35 MPa (3.5 kg / cm2).

 The processing time for a batch of parts is 4 min.

 The treatment has the effect of removing burrs from the surfaces of the parts, the thickness of which can be up to 0.2 mm, while retaining the shine of their surfaces without alteration.

Example 2.
Pieces of 50 × 30 × 10 n, of thermosetting material reinforced with glass fibers, having burrs of thickness up to 0.15 mm in vertical planes, are placed on the surface of the plate next to one another, without spacing.

 The distance between the nose of the mixer of the ejection nozzle and the surface of the parts is 150 mm. The diameter of the suction nozzle channel is 12 mm.

The depth of the helical grooves of the mixer is 1.0 to 1.5 n.

 The hard particles used are crushed flakes of plum and apricot kernels up to 2.0 n in size.

 The speed of rotation of the plate is 4 rpm.

The operating pressure of the compressed air supplying the ejection nozzle is up to 0.45 MPa (4.5 kg / cm2).

 The processing time for a batch of parts is 5 min.

 The treatment has the effect of removing burrs from the surface of the parts, the thickness of which can range up to 0.15 mm, while retaining the shine of their surfaces without alteration.

 Of course, the invention is in no way limited to the embodiment described and shown which has been given only by way of example. In particular, it includes all the means constituting technical equivalents of the means described as well as their combinations if these are executed according to the spirit and implemented in the context of protection as claimed.

Claims (2)

 1.- Method for deburring parts, in particular of thermosetting materials, of the type consisting in causing parts to act, by means of compressed air, a rectilinear flow of hard or solid particles endowed with sufficient kinetic energy to break up and remove the burrs of the parts without altering the gloss of their surfaces, characterized in that the parts are acted upon, in addition to said straight flow, an additional flow of hard or solid particles enveloping the straight flow and moving along a helical path.  2.- Parts characterized in that they are treated by the process which is the subject of claim 1.