WO2007138029A1

WO2007138029A1 - Method for securing ball bearings, and a module component as an example of a food processor with a shaft

Info

Publication number: WO2007138029A1
Application number: PCT/EP2007/055148
Authority: WO
Inventors: Oliver Brech; Michael Schmidt
Original assignee: Vorwerk & Co. Interholding Gmbh
Priority date: 2006-05-31
Filing date: 2007-05-29
Publication date: 2007-12-06
Also published as: TW200819660A; DE102006025307A1

Abstract

The invention relates to a method for securing ball bearings (15, 16) supporting a shaft (10), each of which features an inner ring (21) and an outer ring (20), with a module component (14) guiding the shaft (10), wherein the ball bearings (15, 16) are positioned consecutively axially, as well as such a module component, for example, a food processor. In order further to improve a method of this type, it is suggested that the ball bearings (15, 16) are at first positioned facing each other by means of an attached sleeve (18), and that they are subsequently coated with plastic, at least in the area where the outer rings (20) are located and also covered by the sleeve (18). Thus, the problem addressed, that of further improving a module component, in particular with regard to the anti-twist stop of the ball bearings, is solved first by positioning the ball bearings (15, 16) in an axial direction by means of a first sleeve (18), wherein the first sleeve (18) is merely connected via plug-in to the bearing ring with which it engages, and by providing a second sleeve (22) which is produced by coating the first sleeve (18).

Description

Method for fixing ball bearings and built-in part, for example, a food processor with a shaft

The invention relates first to a method for fixing, a shaft bearing ball bearings, each having an inner ring and an outer ring, with a shaft leading insert, wherein the ball bearings are axially positioned one behind the other.

Methods of the type in question are known. In this case, the outer rings of the ball bearings are injected in compliance with the axial distance, for example. In plastic. Balls, cage and inner rings are then mounted. Finally, a built-in fixture is mounted on the shaft leading to.

Greasing of the bearing balls is only possible after the outer rings have been overmoulded, since the quite high processing temperatures in the injection molding process would damage many of the lubricants, in particular the lubricant intended for use in food processing equipment. In addition, the axial alignment during injection of the bearings in plastic is complex. In addition, there may be a delay in the plastic part. Also, the practice shows that an outer ring of a standard bearing can be deformed during encapsulation.

With regard to the prior art described above, a technical problem of the invention is seen in further improving a method of the type in question.

This problem is solved initially and essentially by the subject matter of claim 1, wherein it is pointed out that the ball bearings are initially distanced in the direction of each other by a plugged sleeve and at least in the area of their outer rings under overlap and the sleeve are molded with plastic. According to this proposed method, a determination of axially spaced ball bearings is achieved, which need not have a separate anti-rotation in the region of the bearing outer ring. According to the proposed method, the ball bearings can be filled with any desired lubricant, since plastic encapsulation does not take place in the immediate, large-area contact area with the respective ball bearing. The ball bearings are initially spaced apart by an attached sleeve, so further preferably due to a press fit between the ball bearing outer ring and associated, more preferably stepped wall of the spacer sleeve. Consequently, one of temperature fluctuations during operation / when using independent safeguard against rotation of the outer ring is created. Such temperature fluctuations can cause disturbances in particular with different coefficients of expansion of the ball bearing outer ring and the receiving region. The sleeve more preferably extends beyond the outer wall region of the outer ring in the context of the proposed method to form an axial inner shoulder, according to which no deformation of the bearing, in particular of the outer ring as a result of the injection pressure can take place in the further encapsulation with plastic. Rather, the distancerbringende sleeve is overmolded with plastic, wherein further the injection mold can be chosen so that the applied plastic at the same time provides a further axial securing of the ball bearings after cooling so namely in particular the backup to the outside axially, while the sleeve the opposite axial securing after inside takes over. In a preferred embodiment, the sleeve is completely surrounded by the plastic material.

The invention further relates to a method according to the features of the preamble of claim 1. In order to further improve a method of the type in question, it is proposed that a ball bearing be received. mende sleeve is overmolded with plastic and then the ball bearings are inserted into the sleeve. Also, according to this method, ball bearings can be filled with any lubricant, since there is no immediate encapsulation with plastic. In addition, no separate anti-rotation device in the region of the bearing outer ring is necessary since, as is preferably provided, at least the area of the sleeve which receives the ball-bearing outer rings is adapted in terms of material to the expansion coefficients of the outer rings. The preferred interference fit, which is taken after encapsulation of the sleeve introduced ball bearing is maintained even during operation or when using the built-in component.

The subjects of the further claims are explained below in relation to the subject-matter of claim 1 and / or in relation to the subject-matter of claim 2, but may also be significant in their independent formulation.

Thus, it is further preferred that the insert is produced by molding. The latter is adapted, for example, to a receiving area receiving the mounting part. Thus, for example, the built-in part may have a collar protruding radially from a cylindrical portion which engages over the sleeve and forms a support surface. Further, the mounting member radially projecting rear grip portions may be formed so as to form a bayonet closure. In a further preferred embodiment, the built-in part and depending on the size of the ball bearing is selected for placement in a household appliance, such as in a food processor, for example, in a mixing vessel of a food processor, wherein the guided through the insert shaft is used to drive a stirrer. In a further preferred embodiment, the sleeve engages only on the outer rings of the ball bearings, so further preferably radially outside, the outer ring covering overlapping. To comply with the axial distance of Ball bearing to each other shaped stage of the sleeve is preferably dimensioned in the radial direction so that this radial dimension is smaller than the radial width of the outer ring, so for example. Approximately half the radial thickness of the ball bearing outer ring corresponds. The radial overlap of the molded plastic part on the axially outer end ring portion of the outer ring also preferably corresponds to a maximum of half the radial dimension of the outer ring, consequently only a relatively small thermal bridge in the course of injection of the plastic is given. The cooled plastic does not work negatively, especially in the radial direction on the outer ring. On the contrary, as a result of the purely axial overlapping of the outer ring in the course of the cooling, an action on the outer ring in the press fit of the sleeve is supported.

In a further preferred embodiment, the sleeve and the molded plastic part are secured against rotation to each other, so on, in particular by constructive measures. In this regard, it is further proposed that the rotation is achieved by a flattening and / or by form-fitting engagement.

The invention also relates to a built-in part of a kitchen machine, for example, with a shaft, wherein the shaft is mounted by means of two ball bearings positioned axially one behind the other, each having an inner ring and an outer ring.

Such built-in components are known, for example as an exchangeable component of a mixing vessel of a food processor, which mounting part supports an agitator in the mixing vessel via the guided shaft. Such a built-in part is further removable in a known manner, for example by forming a bayonet closure or the like, removable, so on, for example, for cleaning or replacement purposes. In order to further improve a built-in part of the type in question, in particular with regard to a rotation of the ball bearings in the fixture with further consideration of a filling of the ball bearings with any lubricant, it is proposed that the ball bearings are positioned by a first sleeve in the axial direction, wherein the first Sleeve with the bearing rings on which it engages only plug-connected, preferably press-connected and that a second sleeve is provided, which is generated by extrusion coating of the first sleeve. According to this embodiment, a built-in part is provided which can be provided with standard bearings without rotation lock on the bearing outer ring, which ball bearings can be further filled with any lubricant. The bearing outer rings are independent of temperature influences, which can cause disturbances, in particular with different coefficients of expansion, secured against rotation and in the axial alignment in the insert in the direction of each other safely danced. As a result, that the first sleeve is initially present as a finished part and the ball bearings are plugged into this sleeve, so for example under formation of press fits and further the second sleeve is made so that it overmoulds the first sleeve, deformations of the bearings are avoided, such as it can be done by direct injection molding by injection pressure. Also, the heat in the course of the injection process is reduced to the ball bearings to a minimum, which allows the use of any type of grease without regard to the processing temperatures of the plastic. Also, any plastics can be used without restrictions with regard to the processing temperature in view of the permissible limit temperature of the lubricant used. The ball bearings are positioned exactly to one another by the first sleeve, as a result of which this exact axial alignment of the ball bearings is independent of the plastics processing and the plastic properties. Furthermore, the area between the ball bearings, which is sealed by the first sleeve, can be used as a bearing for an additional fat depot, which grease for example se may be introduced into the sleeve before driving the second ball bearing. It may be prepared in accordance with a created from ball bearings and first sleeve unit, which is finally encapsulated with plastic to form the second, radially outer sleeve. Alternatively, only the bare first sleeve with plastic can be encapsulated, after which only the ball bearings are pressed into the first sleeve.

The created by the second sleeve backup in the direction of axially outward can be achieved by a complete encapsulation of the circular area, in particular the circular area of the associated outer rings. It is also conceivable in this regard, a partial over-molding of the corresponding annular surfaces, so as to further reduce the thermal bridges during the injection process.

The subjects of the further claims are explained below in relation to the subject matter of claim 7, but may also be significant in their independent formulation.

In a development of the subject invention it is provided that the first and / or second sleeve engages only on the outer rings of the ball bearings. The first, ie radially inner sleeve into which the ball bearings are pressed, can form stop surfaces which extend radially inward, so as to provide an axial securing of the ball bearings in the direction towards each other. With regard to the second, molded or molded sleeve is due to the strong temperature effect in the course of the injection process, no contact with the ball bearings, possibly provided only a smaller area contact with the outer rings of the ball bearings. Thus, further, the second sleeve support the ball bearings axially in the direction away from each other, so in particular by encroachment on the outer rings in the axial direction. The second sleeve also forms at least partially the outer contour of the built-in part; serves accordingly not only the axial securing of the ball bearing in the direction away from each other, but also the formation of example Halterungsausformungen with which the shaft to be guided on the mounting part can be fixed.

The first and the second sleeve are secured against rotation to each other. This can be achieved in the simplest way by welding or gluing the two sleeves to each other. Preferred is an embodiment in which the rotation is achieved by a flattening and / or by positive engagement. Thus, for example, the inner, that is, the first sleeve in plan view have a shape deviating from a circular shape. Also, this first sleeve may have grooves or radial projections, which are correspondingly covered or filled by the plastic material of the second sleeve.

The attack of the second sleeve via a ball bearing is preferably less than half of the radial extent of the outer ring, that is less than half of the ring thickness, further provided the encroachment of the second sleeve on a ball bearing circumferentially or even partially distributed over the circumference can be. Both the first sleeve and the second sleeve are not directly in contact with the shaft. Thus, in particular axially outward, the ball bearing overlapping sealing washers are provided, which are plug-in and / or adhesive in axially projecting beyond the first sleeve, cylindrical portions of the second sleeve.

The first sleeve is adapted to the coefficient of expansion of the ball bearing outer ring, preferably consists of a metal material. The created by encapsulation of the first sleeve second sleeve is made of a plastic material, in particular polyamide. The invention with reference to the accompanying drawings, which is merely an embodiment, explained in more detail. It shows:

1 is a side view of a food processor with a mixing vessel, in which mixing vessel a shaft for a stirrer by means of a

Built-in part is held;

2 shows the base area of the mixing vessel and the receptacle of the food processor receiving the mixing vessel in a sectional view;

Fig. 3 in a perspective, partially sectional view of the mounting part with the guided through this shaft.

First, with reference to FIG. 1, a food processor 1 having a mixing vessel 3 received in a receptacle 2 is shown and described.

Bottom side of the mixing vessel 3, a stirrer 4 is provided. This is driven by an electric motor 5 provided in the food processor 1.

The electric motor 5 and optionally a heating provided are controlled by switches 6, which are integrated in a control panel 7. The mixing vessel 3 together with the agitator 4 can be removed from the receptacle 2 of the food processor 1, to which end the power transmission of the electric motor 5 to the agitator 4 is designed as a plug-in coupling 8.

The stirring vessel-side agitator 4 is mounted on a shaft 9 passing centrally through the bottom 9 of the mixing vessel 3. This shaft 10 forms on the underside of the bottom 9 a non-rotatable coupling end 11, for engaging in a correspondingly shaped molded-on clutch 12 of the motor shaft 13. The shaft 10 is fixed to the mixing vessel 3 or to the dome-like retracted bottom 9 by means of a built-in part 14. This built-in part 14 is centrally penetrated by the shaft 10, which in turn is guided in the mounting part 14 by means of two ball bearings 15, 16 which are spaced apart from one another in the axial direction.

The axial, that is measured in axial extent of the shaft 10 distance between the ball bearings 15 and 16 to each other is essentially defined by a radially enlarged enlarged portion 17 of the shaft 10. At the transition from this radially expanded portion 17 to the adjacent shaft sections Ring stages close in the assembled state, the ball bearings 15 and 16 at.

The determination of the shaft 10 via the ball bearings 15 and 16 is carried out by first mounting a first ball bearing 15 on a shaft portion to the annular stop surface of the radially expanded portion 17. Hereinafter, the shaft / ball bearing unit in one of the same metal material as the ball bearing outer rings existing sleeve 18 is pressed, whose inner diameter corresponds approximately to 1.5 to 2 times the shaft diameter. At the end of each case, the sleeve 18 forms a receptacle 19 which widens radially on the inside. The axial depth of these receptacles 19 substantially corresponds to the thickness of the ball bearings 15, 16 measured in the same axial direction or, more specifically, the thickness of the respective outer rings 20 of the ball bearings 15, 16 measured in this direction.

The radial strength of the annular step formed by the receptacle 19, that is to say the difference in the inner radii in the region of a receptacle 19 and in the middle region between the receptacles 19, amounts to approximately half of the measurements in the radial direction in the illustrated embodiment Thickness of an outer ring 20, so that the axially inwardly facing annular surface of an outer ring 20 is partially covered by the material of the sleeve 18.

The inner ring 21 of the ball bearing 15, which is pushed onto the shaft 10, is mounted in a rotatably fixed manner on the shaft 10 in the usual way. Also, the outer ring 20 is rotatably supported, including this in the manner of a press fit in the associated receptacle 19 of the sleeve 18 is seated.

The space created by the sleeve 18 and axially limited by the ball bearings 15 and 16 in the assembled state is filled with a lubricant.

About the protruding through the sleeve 18 and the other end of the sleeve 18 shaft end, the second ball bearing 16 is reared thereafter, after which this stop limited on the one hand to the radially expanded portion 17 of the shaft 10 and on the other hand formed by the associated receptacle 19 of the sleeve 18 Ring support surface is applied. Also, this ball bearing 16 is both outer ring and inner ring side rotatably supported on the respectively associated fixing part (shaft or sleeve).

By the end-side receptacles 19 of the sleeve 18, the ball bearings 15 and 16 are set apart in the axial direction to each other.

The shaft / sleeve unit is overmolded with plastic, in particular with polyamide or the like, for shaping the built-in part 14. In this way, a second, radially outer sleeve 22 is created, which is initially formed hollow cylindrical with a circular plan. This second sleeve 22 is provided approximately centrally in the axial extent with a radially outwardly projecting collar 23. Radially inwardly protrude from the cylindrical portion of the sleeve 22, starting two axially spaced apart annular collar 24, whose axial distance from each other is defined by the axial length of the molded sleeve 18, so that the annular collar 24 each set over the annular end faces of the sleeve 18 , The radial extent of this annular collar 24 is chosen so that they partially cover the associated end face of the outer rings 20 of the ball bearings 15, 16, and the stop step surface of the sleeve-side receptacles 19, whereby an axial securing of the ball bearings 15, 16 is reached away from each other. The inner sleeve 18 is thereby determined.

The Übergriffmaß the annular collar 24 of the second sleeve 22 via the outer ring 20 of the respective ball bearing corresponds to less than the thickness of the outer ring 20, so in the illustrated embodiment about one fifth of the radial thickness gauge.

The injection pressure and the injection temperature does not act directly on the ball bearings 15, 16, according to the ball bearings 15, 16 at least radially overlapping sleeve 18, whereby a deformation of the ball bearings 15, 16 is counteracted and thus further in the ball bearings and beyond given if also in the created between the ball bearings 15, 16 annular space 25, a grease deposit can be provided.

Turning away from the ball bearings 15, 16, the cylindrical portion of the second sleeve 22 extends in the axial direction beyond the respective annular collar 24, to form a respective end-side receiving portion 26, in each of which a seal 27, which is centrally penetrated by the shaft 10, is inserted - fits.

The two sleeves 18 and 22 are secured against rotation to each other, including a positive connection of the two parts is provided to each other. For this has the ball bearings 15, 16 frictionally receiving radially inner sleeve 18 on the outer circumferential surface a helically extending around the shaft axis x groove 28, in which the plastic material of the sleeve 22 engages.

As an alternative to the described assembly, the sleeve 18 may be encapsulated with plastic unfitted, after which the ball bearings 15 and 16 thereafter are pressed together with the shaft.

The built-in part 14 thus created is inserted from above, that is to say from the interior of the vessel through the bottom 9 of the vessel, for which purpose the bottom 9 has a correspondingly designed central opening 29. On the side of the vessel, the installation part 14 sits flat with its collar 23 on the floor 9.

On the bottom side, a clamping of the built-in part 14 and thus of the entire agitator 4 is provided with clamping of a further contiguous to the axis x arranged vessel foot 30, including a bayonet-type closure is formed. The locking lugs 32 which cooperate with a corresponding coupling part 31 are formed on the fitting part 14, specifically on the outer sleeve 22, and are formed by projections projecting radially outwards and formed in the region of the lower end portion assigned to the coupling end 11.

The agitator 4 is for cleaning or replacement purposes of the bottom 9 of the mixing vessel 3 solvable.

All disclosed features are essential to the invention. The disclosure of the associated / attached priority documents (copy of the prior application) is hereby also incorporated in full in the disclosure of the application, also for the purpose of including features of these documents in claims of the present application.

Claims

1. A method for fixing a shaft (10) superimposed ball bearings (15, 16) each having an inner ring (21) and an outer ring (20), with a shaft (10) leading fitting (14), wherein the ball bearings ( 15, 16) are positioned axially behind one another, characterized in that the ball bearings (15, 16) are initially positioned in the direction of each other by an attached sleeve (18) and then at least in the region of their outer rings (20) under cover and the sleeve (18 ) with plastic.

2. Method according to the features of the preamble of claim 1, characterized in that a ball bearing (15, 16) receiving sleeve (18) is encapsulated in plastic and then the ball bearings (15, 16) are introduced into the sleeve (18) ,

3. The method according to one or more of the preceding claims or in particular according thereto, characterized in that at the same time the insert part (14) is produced by the Umsprit-.

4. The method according to one or more of the preceding claims or in particular according thereto, characterized in that the sleeve (18) engages only on the outer rings (20) of the ball bearing (15, 16).

5. The method according to one or more of the preceding claims or in particular according thereto, characterized in that the sleeve (18) and the overmolded plastic part (22) are secured against rotation to each other.

6. The method according to one or more of the preceding claims or in particular according thereto, characterized in that the Verdrehsiche- tion is achieved by a flattening and / or by positive engagement.

7. built-in part (14), for example, a food processor (1) with a shaft (10), wherein the shaft (10) by means of two axially successively positioned ball bearings (15, 16) each having an inner ring (21) and an outer ring (20) characterized in that the ball bearings (15, 16) by a first sleeve (18) are positioned in the axial direction, wherein the first sleeve (18) with the bearing rings on which it acts only plug is connected and that a second sleeve ( 22) is provided, which is produced by encapsulation of the first sleeve (18).

8. Fitting according to claim 7 or in particular according thereto, characterized in that the first sleeve (18) and / or second sleeve (22) only on the outer rings (20) of the ball bearings (15, 16) engage.

9. Fitting according to one or more of claims 7 to 8 or in particular according thereto, characterized in that the second sleeve (22), the ball bearings (15, 16) axially supports in the direction away from each other.

10. Fitting according to one or more of claims 7 to 9 or in particular according thereto, characterized in that the second sleeve (22) at least partially also forms the outer contour of the mounting part (14).

11. Fitting according to one or more of claims 7 to 10 or in particular according thereto, characterized in that the first sleeve (18) and the second sleeve (22) are secured against rotation to each other.

12. Fitting according to one or more of claims 7 to 11 or in particular according thereto, characterized in that the rotation achieved by a flattening and / or by form-fitting engagement.

13. Fitting according to one or more of claims 7 to 12 or in particular according thereto, characterized in that the encroachment of the second sleeve (22) via a ball bearing (15, 16) is less than half the radial extent of the outer ring (20).

14. Fitting according to one or more of claims 7 to 13 or in particular according thereto, characterized in that the first sleeve (18) and / or the second sleeve (22) not directly with the shaft (10) in

Standing in contact.

15. Fitting according to one or more of claims 7 to 14 or in particular according thereto, characterized in that the first sleeve (18) consists of a metal material.

16. Fitting according to one or more of claims 7 to 15 or in particular according thereto, characterized in that the second sleeve (22) consists of polyamide.