EP2452006B1

EP2452006B1 - Support spider for the drum of a washing machine

Info

Publication number: EP2452006B1
Application number: EP10744730.2A
Authority: EP
Inventors: Marco Angelini; Alberto Vitali
Original assignee: Whirlpool EMEA SpA
Current assignee: Whirlpool EMEA SpA
Priority date: 2009-07-10
Filing date: 2010-07-05
Publication date: 2017-08-23
Anticipated expiration: 2030-07-05
Also published as: EP2452006A1; ITTO20090520A1; WO2011004313A1

Description

The present invention relates to a spider for laundry treating machines equipped with a rotary drum according to the preamble of claim 1.
Laundry treating machines, such as washing machines, washing/drying machines and clothes dryers, are typically equipped with a rotary drum.
Motion is generated by a motor, usually an electric one, and is then transmitted to the drum, which is free to rotate about an axis, whether vertical, horizontal or inclined (depending on the type of laundry treating machine).
In the following description and in the appended claims, the term "spider" will refer to the transmission unit that transmits the motion from the motor shaft to the drum while also acting as a support for the latter.
Known spiders normally comprise three arms spaced at 120° apart and extending from a common hub, which is coupled to a transmission shaft driven by the motor.
At its outermost end, each spider arm has one or more seats for one or more screws, e.g. one pair of screws, for coupling it to the drum edge; the seat is typically cylindrical and threaded, and its axis is perpendicular to that of the motor shaft.
Said threaded seat is very important because this is the point where the strains originating from the exchange of forces between the drum and the spider concentrate; it is therefore of primary importance that said threaded seat is strong and manufactured with the utmost care.
Prior-art spiders (like the ones described in the European patent application EP 1 798 322 A1 by Samsung Electronics and in the UK Patent specification GB 2 006 836 A by Fisher & Paykel) are typically made of metal (because of the loads that they must withstand in operation) and are manufactured by die casting; the aforementioned threaded seats can be obtained on such spiders in two ways: by starting from a solid piece, which is then machined through chip removal machining, or by designing the die appropriately to include such seats.
In the former case, the cylindrical seat for the drum edge coupling screw is first drilled (by using a drilling machine) and then tapped internally. This implies a certain production cost for manufacturing the part, due to the fact that mechanical machining is required in addition to the die casting process.
In the latter case, on the other hand, the threaded seat for the drum edge coupling screw is obtained in the die by using suitable pins.
Moving said pins in a direction orthogonal to that of the main pressing action requires hydraulic or mechanic kinematic systems which increase the overall plan dimensions of the die, resulting in a larger press and a higher hourly cost; along with a longer die casting time, this leads to a higher transformation cost of the part.
It must be stressed that with these solutions the internal metric thread of the cylindrical seat cannot conceivably be made by using a metric self-tapping screw, also known as Spiralform, in order to simplify the production process or reduce the number of steps thereof: in fact, tests carried out have shown that when such a self-tapping screw is used the screw extraction step is extremely difficult, with the result that once the self-tapping screw has been inserted it cannot be extracted without damaging the spider, thus jeopardizing any necessary maintenance steps.
This presumably also derives from the fact that very small fragments of the chip which is formed when making the thread in the cylindrical seat (by the self-tapping screw) are not evacuated and remain trapped between the seat thread and the screw thread.
It is the object of the present invention to provide a spider for laundry treating machines equipped with a rotary drum which can overcome such drawbacks.
It is a further object of the present invention to provide a less costly method for manufacturing such a spider.
Said objects are achieved through a spider for laundry treating machines equipped with a rotary drum according to the first claim and through a method for manufacturing a spider according to claim 7.
The present invention relates to a spider for laundry treating machines equipped with a rotary drum, wherein the seat for the screw used for coupling the spider to the machine drum is defined by at least a first and a second perimetric wall portions, said portions extending on a semicylindrical profile and being arranged at different heights.
The present invention also relates to a method for manufacturing such a spider.
The present invention further relates to a laundry treating machine, such as a washing machine, a washing/drying machine, a clothes dryer or the like, equipped with a rotary drum supported by a spider according to the present invention.
The present invention is based on the idea of simplifying the seat creation step by using a single-movement die and by allowing the use of a metric self-tapping screw for tapping the seat, since the chip formed when inserting the screw is easily evacuated and the spider is thus prevented from being damaged during the removal of the screw.
To this end, the screw seat is defined by opposite and alternated portions which can be obtained through a pressing operation by using a single-movement die, which is beneficial in terms of costs and production times.
Further advantageous features will be set out in the appended claims, which are intended as an integral part of the present description.
These features as well as further advantages of the present invention will become apparent from the following description of an embodiment thereof as shown in the annexed drawings, which are supplied by way of non-limiting example, wherein:

Fig. 1 is a perspective view of a spider according to the present invention;
Fig. 2 is a sectional view of one of the arms of the spider of Fig. 1;
Fig. 3 is a sectional view of the end portion of the spider of Fig. 2;
Fig. 4 is a sectional view of the end portion of the spider of Fig. 3 when mounted on the drum;
Fig. 5 is a perspective view of the end portion of the spider of Fig. 3;
Fig. 6 is a different perspective view of the end portion of the spider of Fig. 3;
Fig. 7 shows a step for in-die production of the spider of the present invention.

Referring now to Fig. 1, there is shown a spider 1 according to the present invention.
In the example shown, it comprises three arms 2, 2A and 2B extending from a common central hub 3 associated with the shaft 4.
The spider 1 acts as a unit for transmitting the motion generated by the motor (through the drive shaft 4) to the drum, as well as a support for the drum itself.
The drum and the spider 1 are secured to each other through fastening screws, for which suitable seats are provided on the free end portion of each arm 2, 2A and 2B.
In particular, the spider is secured to the perimetric edge of the drum by means of one screw per arm, which screw is substantially perpendicular to the axis of the shaft 4.
As can be seen in Fig. 1, the screws are housed in the seats 6, 6A and 6B, which are also visible in Figs. 5 and 6.
The latter are threaded seats for the screw 7 that engages the drum C, and are illustrated more in detail in Figs. 2, 3 and 4.
The holes 5, 5A and 5B are installation reference holes.
The drum C, as shown in Fig. 4, has a cupped edge C1 which is engaged by the screw 7 tightened into the housing seat 6.
As can be seen in Fig. 3, the housing seat 6 is defined by three perimetric wall portions 16, 26, 36, each extending on a semicylindrical profile for a portion of the respective semicylinder, which are arranged at different heights.
In the non-limiting example illustrated herein, each arm is provided with a screw and a respective seat, but more in general the teachings of the present invention are also applicable to two or more seats for a corresponding number of screws.
It is worth mentioning right away that in this non-limiting example the perimetric wall portions 16, 26, 36 are three, but more in general there may be two, four or five of them without departing from the teachings and scope of the present invention.
Said perimetric wall portions 16, 26, 36 that define the housing seat 6 are arranged in such a way as to be opposed to each other in an alternate fashion.
The term "opposed" means herein that there is at least one plane passing through the axis of the cylindrical seat which does not intersects said regions and which separates the cylindrical surface into two semicylindrical surfaces, said portions 16, 26, 36 being arranged in an alternate fashion on said semicylindrical surface; the phrase "in an alternate fashion" means herein that, being said portions arranged at different heights measured along the axis of said cylindrical seat starting from any point of origin, when arranging the portions according to a criterion of increasing height, successive portions will lie on different semicylindrical surfaces.
In short, a discontinuous helicoidal path is defined (resulting in a discontinuous thread).
The arm 2 is produced by pressing, simply by obtaining the housing seat 6, as will be described below, by tapping the initially unthreaded perimetric wall portions 16, 26, 36.
The thread is obtained by using a self-tapping screw 7 which is screwed into the seat 6, thereby removing the necessary chip from the perimetric wall portions 16, 26, 36.
The removed chip is easily evacuated because the thread does not follow a continuous helicoidal path, but features interruptions due to the alternation between the perimetric walls 16, 26, 36, which are arranged opposite to each other in at least one section and in an alternate fashion.
The seat 6 ends towards the edge C1 with an open countersink 46 which is entered into and seized by the widened head of the screw 7, as shown in Fig. 4.
As far as the step of manufacturing the spider 1 is concerned, it is obtained by pressing. Referring now to Fig. 7, there is shown a detail of the step of pressing the free end of the arm 2 of the spider 1.
More specifically, S2 is the matrix of the die and S1 is the punch, and they are made in such a way as to define the housing seat 6 by creating the perimetric wall portions 16, 26, 36 and the open countersink 46.
The arrows in Fig. 7 also highlight the directions of the main movement, by which the die provided by the matrix S2 and the punch S1 is opened.
From the analysis of Fig. 7 it can be immediately deduced that, unlike the die casting process according to the prior art, for creating the seat 6 no additional movement is required (e.g. by using a pin as in the prior art); as a matter of fact, all the best draft angles are preserved for making the arm 2 and the seat 6 in a single step, thereby avoiding any undercuts.

Claims

Spider (1) for laundry treating machines equipped with a rotary drum (C), said spider (1) being fitted with multiple arms (2,2A,2B) extending radially from a common hub (4), wherein the free end of the arms comprises a seat (6,6A,6B) adapted to house a screw (7) for coupling the spider (1) to the drum (C) and engaging said drum (C), characterized in that
said housing seat (6,6A,6B) is defined by perimetric wall portions (16,26,36), each extending on a semicylindrical profile and arranged in such a way as to be opposed to each other in alternate fashion, wherein said perimetric wall portions (16,26,36) define a discontinuous helicoidal path.
Spider (1) according to claim 1, wherein said perimetric wall portions (16,26,36) are arranged at different heights relative to the base of a cylinder being internally tangent to said seat (6, 6A, 6B).
Spider (1) according to any of the preceding claims, wherein each perimetric wall portion (16, 26, 36) extends for approximately 180°.
Spider (1) according to any of the preceding claims, wherein the spider (1) comprises three arms (2,2A,2B) extending from a common central hub (3) associated with a shaft (4), and wherein the axis of said seat (6,6A,6B) is substantially perpendicular to said shaft (4).
Laundry treating machine of the type comprising at least one rotary drum (C) having a cupped edge (C1) adapted to be engaged by a screw (7) tightened into a housing seat (6,6A,6B) of a spider (1) according to one or more of the preceding claims.
Method for manufacturing a spider (1) according to one or more of claims 1 to 4, characterized by comprising the step of making the perimetric wall portions (16,26,36) by pressing.