DE4235637A1 - Prodn. of planetary supports for epicyclic gears for automobiles etc. - includes basic body produced by cold box process with inserted cores for openings in planetary support - Google Patents

Abstract

In the prodn. of a planetary support (esp. for hydraulic torsion dampers) consisting of a cast annular basic body, the novelty is that the basic body is produced by the cold box process with inserted cores for the openings (2,3) in the planetary support (1), the openings being adjusted to the precise final size in the subsequent fettling process. USE/ADVANTAGE - In the mfr. of planetary supports for epicyclic gears for automobiles (e.g. in the transmission between the engine and the clutch), water vehicles and general machine construction. The process involves few operations and few tools and is suitable for simple and inexpensive mass prodn.

Description

The invention relates to a method for manufacturing a planet carrier, especially for hydraulic torsion damper, from an annular, cast base.

Hydraulic torsion dampers are used in Motor vehicles and watercraft and in general Mechanical engineering used. One possible area of application is e.g. B. the arrangement in the drive train of a motor vehicle between the engine and that located in front of the transmission Clutch.

One of the components of a hydraulic torsion damper is a planet carrier, the recesses for tarpaulin possesses ten wheels, which are floating in the planet carrier are arranged. These recesses are over with valve pockets Grooves or recesses connected together, which in turn through overflow channels with the inner and outer circumference wall of the planet carrier.

From practice it is known to make the planet carrier to produce an annular, cast base body. The required recesses and valve pockets are on closing in several steps on one machining center machined with special drilling and milling units, accordingly by spindling, milling and subsequent Circular grinding the recesses and valve pockets be introduced into the base body.

A disadvantage of the known method, however, is that it very expensive, especially very machining intensive and therefore expensive.  

The present invention therefore has the object Basically, a method of making a planet carrier of the type mentioned at the outset, which is due to a rational production is suitable for large quantities, especially the inexpensive and easy to manufacture can.

According to the invention this object is achieved in that the basic body in the cold box process with inserted cores is produced for the recesses in the planet carrier, and that then the recesses in the clearing process on the precise gauge blocks are brought.

The method according to the invention becomes a planet carrier with few operations and few tools posed, which makes him particularly due to his price is suitable for large quantities.

One of the essential features is the cold Box method, through which a high dimensional accuracy of the reason body can be reached. In particular, the division Differences for arranging evenly over the circumference the recesses and valve pockets very precisely and you get a reproducible casting size of z. B. only 0.5 mm deviations. Because of this high accuracy of the body, it is possible the exact dimensional accuracy of the planet carrier or of the recesses and valve pockets of the planet carrier to achieve a broaching process with broaches.

Depending on the number of recesses and Valve pockets can all the same recesses Geometry can be cleared at the same time. Generally are two, four, six or eight recesses and valve bags evenly distributed over the circumference of the planet carrier provided.  

With the method according to the invention, With the help of the clearing process, very precise planet carriers achieve a high surface quality. In particular, e.g. B. by arranging calibration teeth on the broaches, Draw marks avoided.

Has proven to be particularly suitable in practice as a mate rial for the production of the planet carrier according to the invention Gray cast iron highlighted, especially gray cast iron GG 25.

This means that the broaches are easy to clear through the recesses and valve pockets can and their wear is kept as low as possible, can be provided that the pouring bevels less than 60 ° being held.

In practice, the values are particularly optimal a pouring slope of a maximum of 4%.

Another advantage of the method according to the invention is that practically with a single set of work witness all recesses and valve pockets of the same geometry can be cleared.

Below is based on one in the drawing presented embodiment a manufacturing process described in principle. Training a hydraulic Torsional dampers are generally known (see e.g. DE-OS 39 18 063), which is why only the planet carrier below of the hydraulic torsion damper on which the Her position process relates, is described in more detail.  

The planet carrier 1 is made of a ring body in cast iron GG 25. The production takes place in cold box Ver, with recesses 2 for receiving floating planet gears 3 (dashed line) and valve pockets 4 for valve bodies (not shown) are formed by cores. About grooves 5 in the end faces of the planet carrier 1 , the regularly distributed from the recesses 2 are connected to each other and via grooves 6 , the valve pockets 4 are each connected to the interior of the planet carrier 1 .

The base body is manufactured using the cold box process.

In the cold box process, core production is carried out in cold core boxes using synthetic quartz sands that are hardened directly in the core box guided.

The cold box binder consists of an organic two-component system that hardens quickly at room temperature in the presence of a catalyst. Component 1 of the binder is a phenolic resin and component 11 is a polyisocyanate. Both components are dissolved in solvents. In the presence of a catalyst (for this purpose, for example, triethylamine or dimethylethylamine is used), the hydroxyl (OH) groups of the phenolic resin combine with the isocyan (NCO) groups of the polyisocyanate, thus forming a solid polyurethane resin.

Quartz sand with the two binders is used for core production mixed liquids. This sand mixture is used for the core position, e.g. B. by stamping or using core blow or core shooters. The core must be hardened in core box still closed by gassing with an air Catalyst or carbonic acid-catalyst mixture take place.  

The core hardening in the cold box process takes only a few Seconds.

The shooting and curing pressure is 2 to 4 kp / cm ² . The duration of hardening with a core weight of 20 kp is approx. 10 to 30 seconds.

Cold box cores have an equally good strength and Surface quality like hot-box cores, they also do not need any Core reinforcements. Compared to the hot box process, the Heating the core boxes, so that synthetic resin core boxes can be used. The particular advantage is there too see that cold box cores immediately after emptying from the Core box can be inserted into the mold.

After the production of the basic body, in which I only have dimensional deviations of ± 0.5 mm, is in a first machining cycle in a first Step of the base body spanned on a turning center, with the inside diameter and a flat side turned to size become. In a second step, the outside diameter of the planet carrier and the second plane side rotated, being a quality of H 7 according to DIN / ISO should be maintained.

In a further process step, a corresponding number of broaching needles are pulled through the recesses 2 in a single operation in accordance with the number of the existing recesses 2 .

As the next step, the inner contour of the planet carrier 1 is also brought to the desired final dimension with a broach.

The last essential step also represents a broaching process with which all existing valve pockets 4 are also cleared to the exact gauge in one operation with a corresponding number of broaching needles.

If necessary, the three above can be used Clearance procedures in a different row, of course be carried out.

The end grooves 5 and 6 , which are used to connect the valve pockets 4 with the recesses 2 for the planet gears and with the inner and outer periphery of the planet carrier 1 , generally do not have to be machined.

Reference numerals

1 planet carrier
2 recesses
3 planet gear
4 valve pockets
5 grooves
6 grooves

Claims (8)

1. A method for producing a planet carrier , in particular for hydraulic torsion damper, from a ring-shaped, cast base body, characterized in that the base body in the cold box method with inserted cores for recesses ( 2 , 3 ) in the planet carrier ( 1 ) is produced, and that then the recesses ( 2 , 3 ) are brought to the precise gauge blocks in the broaching process. 2. The method according to claim 1, characterized in that the recesses ( 2 ) for the planet wheels ( 3 ) and the valve pockets ( 4 ) of the valve body are cleared. 3. The method according to claim 1 or 2, characterized characterized in that the base body is gray cast iron is used. 4. The method according to claim 1, 2 or 3, characterized characterized that the pouring bevels smaller be held as 60. 5. The method according to claim 4, characterized records that the casting bevels less than 4 ° being held. 6. The method according to claims 1 to 5, characterized characterized in that the base body after the Pour on its inside in a first process cycle diameter and turned on a plan side and then turned on the outside diameter and the second face becomes.   7. The method according to claim 6, characterized in that in a second process cycle, the recesses ( 2 ) are machined with broaches, after which the inner contour of the base body is machined in a broaching process in a further step. 8. The method according to claims 5 and 6, characterized in that in a further process step Ver the valve pockets ( 4 ) are cleared.