WO2019023802A1 - Dispositif et procédé de réduction du frottement entre des objets élastiques et des surfaces - Google Patents

Dispositif et procédé de réduction du frottement entre des objets élastiques et des surfaces Download PDF

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Publication number
WO2019023802A1
WO2019023802A1 PCT/CA2018/050942 CA2018050942W WO2019023802A1 WO 2019023802 A1 WO2019023802 A1 WO 2019023802A1 CA 2018050942 W CA2018050942 W CA 2018050942W WO 2019023802 A1 WO2019023802 A1 WO 2019023802A1
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WO
WIPO (PCT)
Prior art keywords
friction
guiding structure
resilient
reducing
reducing object
Prior art date
Application number
PCT/CA2018/050942
Other languages
English (en)
Inventor
Jean THERRIEN
Yannick Longpré
Original Assignee
Mi Intégration S.E.N.C.
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Mi Intégration S.E.N.C. filed Critical Mi Intégration S.E.N.C.
Publication of WO2019023802A1 publication Critical patent/WO2019023802A1/fr

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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
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C29/00—Bearings for parts moving only linearly
    • F16C29/005—Guide rails or tracks for a linear bearing, i.e. adapted for movement of a carriage or bearing body there along
    • 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
    • F16C29/00—Bearings for parts moving only linearly
    • F16C29/04—Ball or roller bearings
    • F16C29/045—Ball or roller bearings having rolling elements journaled in one of the moving parts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/14—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles
    • B29C45/14065—Positioning or centering articles in the mould
    • B29C2045/14139—Positioning or centering articles in the mould positioning inserts having a part extending into a positioning cavity outside the mould cavity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/14—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles
    • B29C45/14467—Joining articles or parts of a single article
    • 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
    • F16C2202/00—Solid materials defined by their properties
    • F16C2202/02—Mechanical properties
    • F16C2202/04—Hardness
    • 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
    • F16C2208/00—Plastics; Synthetic resins, e.g. rubbers
    • F16C2208/10—Elastomers; Rubbers
    • 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
    • F16C2208/00—Plastics; Synthetic resins, e.g. rubbers
    • F16C2208/20—Thermoplastic resins
    • 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
    • F16C2220/00—Shaping
    • F16C2220/02—Shaping by casting
    • F16C2220/04—Shaping by casting by injection-moulding

Definitions

  • This invention relates generally to positioning of objects into manufacturing positions. More specifically, this invention relates to devices and methods for reducing friction between resilient objects and non-resilient surfaces when positioning resilient objects into manufacturing positions.
  • Injection molding is a manufacturing process that often requires that parts of unfinished objects, sometimes referred to as a substrate, be inserted into a mold prior to injection of a molten thermoplastic or thermoset (which may be, for example, an elastomer or resin) to over- mold the substrate thereby completing the object to form a finished product.
  • a molten thermoplastic or thermoset which may be, for example, an elastomer or resin
  • the insertion of the substrate (object) may require extensive force especially when the substrate comprises rubber or thermoplastic surfaces that create high frictional forces between the substrate and the metal surface of the mold.
  • the problems associated with high friction coefficients are numerous and include injuries to operators, imprecise positioning of objects within manufacturing processes, damage to the objects, etc.
  • Friction of elastomers, such as rubber, on metal is particularly problematic. Rubber (and elastomers in general) exhibits a complex frictional behavior that includes two main components: surface adhesion and hysteretic or "internal" friction due to the bulk behavior of rubber.
  • Lubricants are not particularly desirable for manufacturing objects as they often require cleaning afterwards.
  • Air cushions can be difficult to integrate in a manufacturing process.
  • Devices based on ball bearings are known, for example, in conveyors.
  • So-called ball transfer plates are used in different types of conveyors to reduce friction between objects and a surface.
  • the ball sockets of ball transfer plates comprise multiple parts which can interfere with the rubber rolling/sliding in addition to imposing a lower limit on the size of the balls in view of the difficulties in manufacturing very small multi-part sockets.
  • their relative complexity is not ideal for certain types of manufacturing processes such as high-pressure injection molding.
  • Figure 1 is a perspective view of a friction-reducing object-guiding structure in accordance with one embodiment of the invention.
  • Figure 2 is a cross-sectional view of a friction-reducing object-guiding structure in accordance with alternative embodiments of the invention.
  • Figures 3 is a cross-sectional view of a friction-reducing object-guiding structure in accordance with alternative embodiments of the invention in which rolling elements are located on a plurality of faces of the structure.
  • Figure 4 is a top view of a section of a friction-reducing object-guiding structure in accordance with one embodiment of the invention.
  • Figure 5 is a cross-sectional view of a friction-reducing object-guiding structure in accordance with alternative embodiments of the invention.
  • Figure 6 is a perspective view of a manufacturing system comprising a friction-reducing object-guiding structure in accordance with alternative embodiments of the invention.
  • Figure 7 is a cross-sectional view of a friction-reducing object-guiding structure in accordance with alternative embodiments of the invention having a resilient object engaged thereon.
  • Figure 8A is a top view of a section of a friction-reducing object-guiding structure in accordance with alternative embodiments of the invention.
  • Figure 8B is a cross-section view taken at the dotted line of Figure 8A.
  • Figure 9 is a perspective view of a friction-reducing object-guiding structure in accordance with alternative embodiments of the invention mounted on tracks.
  • Figure 10 is a perspective view of a manufacturing system comprising a friction- reducing object-guiding structure in accordance with alternative embodiments of the invention shown with a position detector.
  • One aspect of the present invention is a friction-reducing object-guiding structure comprising a body having at least one non-resilient surface for guiding a resilient object thereon, said body comprising a plurality of integrally formed cavities (sockets) in the at least one non-resilient surface, each cavity comprising an opening and a flexible flange and configured to receive a rolling element, each of said rolling element partially protruding above the at least one non-resilient surface, wherein the flexible flange comprises an upper part that is formed by the at least one non-resilient surface.
  • in yet another aspect of the present invention is a method for positioning an object into a manufacturing position within a manufacturing device.
  • the method comprises providing the friction-reducing object-guiding structure as described above, engaging the resilient object on the friction-reducing object-guiding structure to allow displacement of the resilient object on the friction-reducing object-guiding structure while contacting the plurality of rolling elements, and displacing the resilient object on the friction-reducing object-guiding structure to reach the manufacturing position.
  • resilient object it is meant a generally deformable object (e.g. substrate) made completely or partially of elastomeric material such as, but not limited to, rubber.
  • non- resilient surface it is meant a surface that is harder than the resilient object and which cannot be deformed by the resilient object.
  • the non-resilient surface is generally a smooth surface such as metal or hard plastic.
  • the friction-reducing object-guiding structure 5 in Figure 1 is shown in one exemplary configuration in the form of a blade with the resilient object representing a car weather strip 8 engaged on the friction-reducing object-guiding structure.
  • the friction-reducing object-guiding structure 5 comprises a plurality of rolling elements 9 partially protruding from its non-resilient surface 24 that provide the means by which friction is reduced as will be further described below.
  • the blade of Figure 1 thus functions as a low-friction guiding member to guide the object into the desired position for subsequent manufacturing processing such as injection molding.
  • rolling element it is meant an element that comprises a rounded shape and may include, without being limited to, spheres (balls) and cylinders.
  • the rolling elements may be solid or hollow.
  • the rolling elements shown in Figure 1 are aligned and equally spaced in rows and columns. In other embodiments, the rolling elements needs not be arranged with equal spacing and/or in rows and columns as shown by way of example in this figure.
  • the friction- reducing object-guiding structure 5 comprises a body 10 with a plurality of cavities (sockets) 12 configured to retainably receive the rolling elements therein.
  • Retainably receiving the rolling elements means that rolling elements are free to roll or rotate within their respective cavities and cannot escape, during normal rolling action, from the cavities because of the retaining effect of the flexible flange 20 which is further described below.
  • the cavities are integrally formed in (built-in) the body 10 and are defined by a cavity wall 14 or walls, a cavity bottom 16 and an opening in the surface of the friction-reducing object-guiding structure to allow the rolling elements to partially protrude above the plane of the surface 24.
  • the cavities' walls and bottoms are an integral part of the body 10.
  • the friction-reducing object-guiding structure 5 is shown with an elastomeric object 11 on it.
  • the cavity bottom 16 may be flat as shown in the Figures 2 and 3 or it may be curved.
  • the cavity bottom 16 may be deformable or resilient to flex or deform when pressure is applied to the rolling elements 9 during the injection molding process.
  • the rolling elements 9 may be spring-loaded and/or linearly displaceable to enable a user to adjust the depth of the rolling elements 9 in their cavities.
  • the cavities 12 are configured to receive rolling elements 9 such as spheres or cylinders.
  • the cavities preferably have the shape of an empty cylinder, such as a right circular cylinder with a radius r which is equivalent to the width (wall to wall) of the cavity as shown in a cross-sectional view in Figure 2.
  • the cavities may have a rectangular shape.
  • all of the rolling elements are of identical size and are made of the same material.
  • the rolling elements may be of different sizes.
  • the tops of the different rolling elements define a common plane and therefore when rolling elements are of different sizes the sockets size is accordingly different.
  • the rolling elements may be made of different materials.
  • the cavity wall 14 (or walls) comprises flanges 20 around each socket/cavity for retaining each rolling element 9.
  • the flanges are configured to allow each rolling element to partially protrude above the surface 24.
  • the flange is a single continuous annulus around each socket.
  • the flange is a discontinuous multi-part annular member having a plurality of arced sectors divided by slits.
  • the flange 20 is preferably continuous all around the perimeter of the cavity.
  • the flanges 20 are preferably integrally formed in the body 10 and are flexible.
  • flexible it is meant that flange is elastically deformable, i.e. more malleable or resilient than the rolling element.
  • the rolling action of the rolling element 9 is enabled by the relative dimensions of the rolling elements and the cavities.
  • the width of the opening measured at the tip of the flange i.e. the internal diameter of the undeformed flange (i.e. prior to inserting the rolling element in the socket)
  • the equatorial diameter may be slightly larger than the diameter of the cross-sectional circle of the sphere or the cylinder immediately adjacent the tip of the flange to leave a little bit of slack or "wiggling" room.
  • the spacing between adjacent cavities 12 is greater than the diameter of each rolling element 9. In other embodiments, the spacing between adjacent cavities 12 may be less than the diameter of each rolling element 9.
  • the body 10 comprises a groove 22 around the opening of the cavities ( Figure 4).
  • the groove is formed by a depression in the surface 24 of the friction-reducing object-guiding structure and extends into the cavity 12 to form the upper part of the flange 20.
  • the flange thus has an upper edge 26 that is at an angle relative to the surface 24 as shown in Figures 2 and 3.
  • the groove 22 can be advantageous to reduce both the internal friction and surface adhesion of rubber by providing a space that allows the rubber to deform in the vicinity of the rolling element (e.g. sphere) without touching the surface or touching with less force thereby reducing the energy absorbed (internal friction) by the rubber.
  • the groove/rolling element arrangement contributes to reducing surface adhesion (reducing contact surface and surface adhesion) but also reduces the internal friction component of friction.
  • the reduction of both components of the friction is particularly advantageous in the context where the force applied on a resilient object being displaced or positioned in manufacturing system by human operators may vary significantly between operators, or even for a same operator, for a same object and same manufacturing system. Therefore both components of the friction will vary, making an ideal determination of the design and dimensions of the friction-reducing object- guiding structure for a particular application difficult.
  • the embodiment of the invention in which a groove is present provides additional flexibility to design the configuration/dimensions of the friction reducing parameters (protrusion height, size of rolling elements, spacing between rolling elements, size of the grooves) such that a particular configuration can reduce friction for a range of forces likely to be encountered for a particular resilient object/manufacturing system.
  • the optimal dimensions (depth, angle, surface area) of the groove 22 depend of several factors. These factors include, without being limited to, the degree of deformability of the resilient object 11 , the required height (protruding height) of the rolling elements 9 above the surface 24, the force or range of forces that is applied to the resilient object against the surface, the speed at which the resilient object is displaced laterally (along) the surface, the temperature and the like.
  • the cavities 12 can be manufactured by drilling holes with a diameter, or width, slightly larger than the diameter of the sphere, or the cylindrical cross-sectional width of a cylinder, and a depth that is calculated to provide the desired protruding height of the rolling element.
  • the flange 20 and groove 22 can be created by using a groove forming sphere with a diameter larger than the sphere to be inserted in the cavity 12, and therefore larger than the diameter or width of the cavity 12, and applying a force while it is sitting on top of the opening. This creates downward forces to form a depression in the surface around the opening. But it also creates tangential forces along the curvature of the groove forming sphere such that part of the surface 24 is pushed towards the inside of the cavity thereby creating the flange 20.
  • the force applied to create the groove and flange depends on the desired depth of the groove, which directly influences the position (depth) of the flange, and the required height of the protrusion.
  • a reinforced steel groove forming sphere of about 4-6 mm can be used for a body made of steel and openings with diameters or widths of about between 2 and 3 mm.
  • the force applied to the groove forming sphere is generated by, or the equivalent of, a weight of about 2.3 kg (5 pounds) dropping on the groove forming sphere from about 4 inches (about 10 cm) high.
  • a punch with a groove forming sphere or part thereof at one end and a mechanism configured to generate the appropriate force can be used. It will be appreciated that the dimensions of the groove forming sphere and forces involved can be adjusted to create the desired dimensions of the groove 22 and the flange 20.
  • the rolling element is a cylinder
  • a groove forming cylinder having a cylindrical diameter larger than the cylinder used as rolling element can be used to form the groove.
  • the spheres or cylinders may typically protrude above the surface by about 10 to 40% of their radius and preferably by about 30 to 40%, in some embodiments, to provide a contact surface with the resilient object.
  • the spheres may not necessarily be perfectly round (i.e. spherical) and/or smooth. They may exhibit certain shapes (e.g. spheroid) that still allow rolling motion within the cavity while enhancing friction force with the object for better "gripping". Small depressions or dimples on the spheres as seen on golf balls could, for example, be used.
  • the rolling elements 9 are inserted into the cavities 12 by pushing it against the flexible flange(s) 20 which is temporarily and/or partially deformed so that once the sphere or cylinder is inserted its equator is slightly below the tip 21 of the flange.
  • the equator it will be understood, is a plane of symmetry of the sphere or cylinder that extends through the centroid of the sphere or cylinder.
  • the rolling elements 9 are more rigid than the flange(s) 20 and the flange(s) will deform elastically to allow the rolling elements to be pushed into the cavity 12.
  • the flange deforms elastically such that it returns substantially, or sufficiently, to its original position after the rolling element has been press-fitted or snapped into the socket to retain the element therein.
  • the flexible flange is thus configured (sized and shaped) to deform, resiliently at least in part, as the rolling element is pressed into the socket.
  • the flexible flange deforms from a first (i.e. original, undeformed) position to a second (flexed or deformed) position and regains part of its original shape once the rolling element greatest cross-section (mid part for a sphere) is below the tip of the flange.
  • the rolling element is thereby retained in the socket. It will be appreciated that this metal resiliency is dependent on the nature of the metal the size of the flange, hardness of the rolling element and the like.
  • the flexible flange is sufficiently elastically deformable such that it returns to within 50%, preferably within 10%, of its original undeformed position from its maximum deflection after insertion of the rolling element.
  • the rolling elements can be made of various materials such as metal (e.g. stainless steel or aluminum), ceramic, plastic, glass, and the like.
  • metal e.g. stainless steel or aluminum
  • ceramic e.g., ceramic
  • plastic e.g., glass
  • the rolling elements may be made, for example, of hardened steel while the body 10 of the friction-reducing object-guiding structure 5 may be made of steel which is slightly softer than hardened steel.
  • the groove/rolling element arrangement of at least some of the embodiments of the invention also provides a better seal to prevent debris from entering the cavities 12 than ball sockets known in the prior art which often necessitate a special seal to be manufactured and inserted in the socket for this purpose.
  • the upper edge 26 of the flange may also be coplanar with the surface 24. In this embodiment there is no groove 22.
  • the flange 20 may be created by forming an undercut in the cavity. In the case where the body 10 is made of metal an electoerosion process with appropriately shaped electrodes may be used.
  • the rolling elements 9 may optionally be coated and/or roughened to enhance the coefficient of friction of the surface of the elements.
  • the choice of the material is a function of the nature of the object, especially its surface. It will be appreciated that a degree of friction between the surface of the resilient object and the rolling element is necessary to generate the reciprocal movement of the balls and the object.
  • metal balls provide a necessary and sufficient friction with rubber but may not work as well if the surface of the object would be made of less deformable material.
  • Metal rolling elements are particularly well suited for materials such as elastomeric materials such as rubber or TPV (thermoplastics).
  • the cavities 12 are configured to retain the sphere or cylinder immobilized (non-rotating) therein.
  • the rolling elements 9 may be slightly larger than the cavity 12 which is deformed when the rolling element is inserted thereby making significant contact with the rolling element to prevent its rolling when the resilient object is displaced on the friction-reducing object-guiding structure 5.
  • the flanges 20 may be configured so that they make contact with the rolling element even after the rolling element has been inserted.
  • the pattern (disposition and spacing) of the spheres or cylinders on the surface or surfaces of the body 10 of the friction-reducing object-guiding structure 5 is dependent on the shape of the resilient object, the position within the manufacturing device, the required friction reduction and balance between friction coefficient and friction reduction and the like.
  • spheres are arranged on both sides of a plate or blade and on the edge engaging the recess of the resilient object.
  • the spheres provide multiple rolling contact points (or rolling contact zones).
  • the friction-reducing object-guiding structure may exhibit a variety of possible configurations depending on the case.
  • Figure 5 shows a different embodiment of the invention.
  • the friction- reducing object-guiding structure has a pentagonal cross-section defined by two inclined surfaces having rolling balls and two parallel surfaces having rolling balls.
  • the friction-reducing object-guiding structure may have other shapes or geometries to accommodate differently shaped objects.
  • the surfaces can be curved with a radius of curvature that is sufficiently small as to not interfere with the configuration of the cavities or grooves/cavities.
  • the rolling elements 9 and the cavities 12 on the two faces of a plate can be configured to allow the rolling elements to make contact with each other to produce a knock-on effect when the object is engaged and displaced on the friction-reducing object-guiding structure.
  • the rolling elements and/or the surfaces of the friction-reducing object-guiding structure may also be coated to reduce the friction of the elements within the cavities.
  • the coating may comprise friction-reducing nanomaterial such as silicone. It may be applied by plasma coating. The choice of the coating may have to be balanced with the minimum friction required to "grip" the object.
  • the sphere/cavities configuration may also or alternatively comprise a continuous cavity (or slot) comprising a plurality of spheres and allowing the spheres to not only roll within the cavity but to move in the direction of the displacement of the object.
  • the friction-reducing object-guiding structure may comprise a rolling elements motion actuator that provides a force to generate rolling motion independent of the force applied by the friction with the moving resilient object.
  • the actuator may be mechanical or magnetic for example.
  • Such an actuator could include a plate slidingly insertable in the body 10 and making contact with the rolling elements 9 inside the body 10 whereby the sliding of the plate in and out generates a radial rolling force by friction with the spheres/cylinders.
  • the size of the rolling elements 9 is chosen to optimize the displacement of the object with regard to friction, and ease and precision of positioning.
  • the optimization may take into account a balance between friction and precision positioning since in the hypothetical case where the friction would be almost eliminated, it could be very difficult to accurately position the resilient object since the slightest force would create undesirable movement of the resilient object.
  • the friction-reducing object-guiding structure 5 can serve as a guide member to position an object in a manufacturing position within a device, machine or system such as an injection mold.
  • the insertion of resilient, elastomeric materials, such as rubber objects, into manufacturing positions can be particularly difficult because of the high friction forces involved in the contact between the rubber and metal. Rubber is difficult to slide on surfaces such as metal because of very high friction coefficients, especially when the rubber is cold.
  • an injection mold for overmolding of objects or substrates comprising resilient material such as elastomeric material is schematically represented in Figure 6.
  • the mold comprises a first mold part 40 and a second mold part 42. With the mold open, the substrate(s) (such as rubber extrusions) 43 can be inserted and positioned in the first mold part in a first recess or mold cavity 44.
  • the second mold part or a section thereof comprises a second recess 46 that cooperate with first recess 44 to form a closed cavity around the inserted substrate when the first and second mold parts are in a closed configuration.
  • the cavity is designed to provide the desired overmolding shape.
  • the friction-reducing object-guiding structure 5 may serve as a guide member and be designed to be part of the mold.
  • the substrate is inserted into the mold by sliding the substrate onto the friction-reducing object-guiding structure and into position.
  • the friction-reducing object-guiding structure provides flexibility in the manner by which the substrate is inserted.
  • the substrate may be slid over the length of the friction-reducing object-guiding structure or by sliding the substrate 43 down onto the friction-reducing object-guiding structure 5 or a combination of both.
  • the reduction in the force required to position the substrate 43 enables more flexibility in the design of the mold by allowing certain substrate/mold configurations that would be otherwise precluded due to the excessive force required to position the substrate or because of damage caused to the substrate by the friction force. For example by enabling insertion of longer rubber extrusions.
  • the substrate 43 can be, for example, an automotive weathering strip or sealing part having a recess 46, a carrier 48, which is a rigid part to keep the shape of the substrate and provide clipping force.
  • the substrate 43 is shown engaged on the friction- reducing object-guiding structure 5 in the shape of an elongated blade (as in Figure 1 , shown in cross-section in Figure 7) so that an edge (or "contour edge") of the blade engages in the recess and the object is moved (slid) onto its manufacturing position.
  • the surface of the weathering strip in the recess makes contact with the rolling elements (spheres or balls) 9 and their rolling action facilitates the sliding of the strip along the guide member.
  • the substrate 43 is a car weathering strip having lips 50 that play an attachment role when incorporated into a car assembly structure.
  • the lips 50 may also be made of elastomeric material and, because of their relatively fragile design, are particularly prone to friction damage during a manufacturing process such as injection overmolding. It has been found that the friction-reducing object- guiding structure 5 of the present invention is particularly efficacious in protecting such delicate structures subjected to friction over surfaces such as metal surfaces.
  • the lips are particularly easy to deform they exhibit a fairly high internal friction when contacting the surface 24 as the substrate is displaced on the friction- reducing object-guiding structure.
  • the surface recesses 52 contribute to reduce the adhesion friction and the internal friction of the lips as they are successively biased towards the main body of the substrate 43 when contacting the rolling elements 9 and relaxing back to their original positions in between the rolling elements when the substrate is displaced on the friction-reducing object-guiding structure.
  • this particular embodiment has been described using the lips 50 but the contribution of the surface recesses 52 to reducing friction is not limited to the particular substrate shown in Figure 7.
  • the surface recesses 52 may also contribute to reducing friction of substantially flat substrate members, particularly when uneven forces are applied to the substrate to displace it on the friction-reducing object- guiding structure.
  • the recesses 52 also provide additional flexibility in the design of the friction-reducing object-guiding structure 5. For example, the additional friction reduction created by the recesses 52 may enable a design in which the height rolling elements 9 protruding above the surface 24 or their size or their number are reduced since the loss of friction reducing effect of the rolling elements may be compensated by the recesses 52.
  • the friction-reducing object- guiding structure can have a width (width of the edge) requirement of less than about 5.0 mm and in some instances less than about 2.5 mm to avoid deformation of the strip.
  • the blade has a width of about 2.5 mm
  • the spheres have a diameter of about 2.3 mm of which about 0.5 mm protrudes from the surface 24 and about 1.8 mm is below the surface. That is to say, the cavities 12 have a depth of about 1.7 mm.
  • the width or diameter of the cavity is between about 2.3254 and 2.35 mm providing an average gap between the rolling element 9, at its greatest cross-section, and the wall 14 of between about 0.0127 to 0.025 mm.
  • the flange 20 as a length (wall 14 to tip of flange) of about 0.013 and 0.03 mm after the rolling element has been inserted in the cavity 12.
  • the dimensions can be different from this example depending on the specific resilient object and manufacturing process.
  • the rolling elements 9 when the substrate is in contact with the rolling elements 9 and displaced on the friction-reducing object-guiding structure, the rolling elements may be pushed against the flange 20 and/or the wall 14 on one side or one section of the cavities 12 while still retaining their ability to roll.
  • the friction-reducing object-guiding structure 5 may comprise one or more stoppers configured to prevent the substrate from moving on the friction-reducing object-guiding structure once positioned inside the mold and during injection.
  • a stopper in the form of a projecting edge 55 is provided on the friction-reducing object-guiding structure and on which the back of the substrate 43 rests to prevent the substrate from recoiling during injection.
  • the one or more stoppers may be moveable to adjust their position as required.
  • the friction-reducing object-guiding structure may be in the mold when the substrate is inserted therein, in one embodiment it is located externally to the mold to allow positioning of the substrate thereon and subsequently sliding or inserting the friction- reducing object-guiding structure with the object thereon into the mold.
  • the mold may comprise coupling members such as a rail or recess or track 58 for sliding or inserting the friction-reducing object-guiding structure, such as a blade, in the mold.
  • External tracks 60 may also be provided. This facilitates the handling of the substrate by allowing the operator to mount the substrate on the friction-reducing object-guiding structure
  • the one or more stoppers can also be used to guide the positioning of the substrate which can be difficult in the context of molds with complex mold cavities.
  • a stopper abutment(s) may be positioned at
  • a part of the friction-reducing object-guiding structure is located externally while another part is in the mold and the substrate can be mounted externally and subsequently slid in and out the mold by transferring from the external part to the internal part inside the mold (and vice versa to remove the substrate from the mold).
  • the external and internal parts may also be separate parts that are coupled, for example mechanically coupled, after the substrate has been mounted externally.
  • the friction-reducing object-guiding structure may comprise several parts.
  • the friction-reducing object-guiding structure may comprise two plates creating a corridor or channel through which an elongated object can be inserted and pushed or slid into its manufacturing position.
  • the rolling elements 9 such as spheres can be positioned only on the side of the plates facing the object.
  • the friction-reducing object-guiding structure may be mounted on a stationary support and slid on that support into position inside the mold.
  • the friction-reducing object-guiding structure may be a blade as shown in Figure 1 further comprising a recess and slideably engageable on another blade.
  • the sliding may be enabled by sliding tracks such as a drawer sliding mechanism.
  • the friction-reducing object-guiding structure can be part of the mold itself. That is to say the friction-reducing object-guiding structure may form an integral part of a mold wall, for example.
  • body 10 of the friction-reducing object-guiding structure 5 may be the mold walls/cavities themselves.
  • the rolling elements 9 may protrude from the faces of the mold that engage the resilient object as it is inserted into position.
  • the invention thereby provides multidimensional friction-reduction geometries through a combination of guide member shape and distribution of rolling elements.
  • an injection mold system comprising a friction-reducing object-guiding structure and a position detector. It is often difficult to determine the exact position of the substrate(s) especially when parts of the substrate are hidden from view in the mold.
  • the control of the force exerted on the substrate to displace the substrate, even with a friction-reducing object-guiding structure, is not necessarily perfect and may render precise positioning, as required in injection overmolding, difficult.
  • a position detector 62 such as a laser position detector emitting a laser beam, may be used to detect the position of the substrate inside the mold and to provide a signal indicative of the position to the operator to make manual adjustments or to a
  • the microcontroller to automatically trigger a stop when the substrate has reached the desired position within the mold.
  • the position detector 62 may therefore be coupled to a signal processor 64 and/or microcontroller to generate appropriate signals or automated actions.
  • the friction-reducing object-guiding structure may also be used to mount resilient objects or substrates onto other object supports or bases for further processing or
  • the friction-reducing object-guiding structure may be incorporated into the tape laying system described in WO2017049390.
  • a method for positioning a resilient object into a manufacturing position within a manufacturing device such as an injection mold.
  • the method comprises steps of providing a friction-reducing object-guiding structure as described above, engaging the object on the friction-reducing object-guiding structure to allow displacement of the object on the friction-reducing object-guiding structure while contacting the plurality of rolling elements and displacing the object on the friction-reducing object-guiding structure to reach the manufacturing position.
  • an injection mold is shown in the open position (prior to injection) and rubber extrusions 43 (a rubber part such as an automotive sealing part) to be overmolded to manufacture a finished part are inserted in the mold prior to injection using friction-reducing object-guiding structures 5 in accordance with an embodiment of the invention.
  • the friction-reducing object-guiding structure can be an intrinsic (or integral) part of the mold or can be a separate part that is placed in the open mold prior to inserting the rubber extrusion 43 or with the rubber extrusion already on the friction-reducing object-guiding structure.
  • the friction-reducing object-guiding structure is a guide member in the form of a plate or blade with ball bearings rollingly retained in the blade on each side of the blade and on the edge of the friction-reducing object-guiding structure 5.
  • the rubber extrusions 43 having a recess, are slid on the friction-reducing object-guiding structure into position within the open mold.
  • the insertion can be done manually or by an automated process, e.g. by a robot.
  • the blade length spans substantially the length of the mold but this needs not be the case. It will be appreciated that the size, shape and position within the mold of the friction-reducing object-guiding structure will depend on the nature of the finished product and the part being overmolded.
  • the mold is closed and injection is performed to overmold the rubber extrusions. Then, after a cooling period, the mold is opened and the finished product is removed.
  • the guide member because of its friction-reducing object-guiding properties, also facilitates the removal of the finished product from the mold.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)

Abstract

On décrit une structure de guidage d'objets et de réduction du frottement qui peut réduire le frottement d'objets élastiques se déplaçant sur une surface non élastique, tels que du caoutchouc sur du métal. Cette structure comprend une pluralité de cavités formées d'une seule pièce pour recevoir un élément roulant saillant partiellement de la surface.
PCT/CA2018/050942 2017-08-01 2018-08-01 Dispositif et procédé de réduction du frottement entre des objets élastiques et des surfaces WO2019023802A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201762539669P 2017-08-01 2017-08-01
US62/539,669 2017-08-01

Publications (1)

Publication Number Publication Date
WO2019023802A1 true WO2019023802A1 (fr) 2019-02-07

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4858293A (en) * 1986-11-12 1989-08-22 Raychem Corporation Method of forming a bearing by dimensional recovery of a race or rolling element
DE4004160A1 (de) * 1989-03-01 1990-09-06 Bluemle Blueco Technik Manuell betaetigbare flexible transport- oder montageeinrichtung fuer paletten
US6478466B1 (en) * 2000-11-20 2002-11-12 Inventec Appliances Corp. Sliding mechanism
US7650979B2 (en) * 2004-12-08 2010-01-26 Portec, Inc. Ball transfer device
US8052326B2 (en) * 2002-10-14 2011-11-08 Apa Parafricta, Ltd. Linear bearing
US20130264174A1 (en) * 2012-04-10 2013-10-10 Krones Ag Roller-type conveyor for plastics material pre-forms

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4858293A (en) * 1986-11-12 1989-08-22 Raychem Corporation Method of forming a bearing by dimensional recovery of a race or rolling element
DE4004160A1 (de) * 1989-03-01 1990-09-06 Bluemle Blueco Technik Manuell betaetigbare flexible transport- oder montageeinrichtung fuer paletten
US6478466B1 (en) * 2000-11-20 2002-11-12 Inventec Appliances Corp. Sliding mechanism
US8052326B2 (en) * 2002-10-14 2011-11-08 Apa Parafricta, Ltd. Linear bearing
US7650979B2 (en) * 2004-12-08 2010-01-26 Portec, Inc. Ball transfer device
US20130264174A1 (en) * 2012-04-10 2013-10-10 Krones Ag Roller-type conveyor for plastics material pre-forms

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