EP1464711A1 - Method and apparatus for hardening of annular workpieces - Google Patents

Abstract

A hardening process for hardening a ring-shaped workpiece, e.g. a sliding sleeve with a cooling agent, where the workpiece is put on a solid mandrel, subjected to the action of the cooling agent, the workpiece is removed from the mandrel, impacted with a cold gas in a cooling chamber, and the mandrel is removed. An independent claim is included for a hardening device having a device for feeding the hot workpiece and slipping it over a fixed mandrel (30,130), and cooling device-mandrel (40,45), outside the cooling chamber (20), where the mandrel is prepared in the cooling chamber (20) filled with cold gas ready for slipping the workpiece over it.

Description

The invention relates to a method and an apparatus for quenching ring-shaped, metallic workpieces, for example of sliding sleeves for Vehicle transmissions.

From the document EP-A-45 881 is a device for hardening internally toothed Known gears in which a pre-centering dome with an externally toothed Härtedom inserted into the interior of the gear to be hardened, the hardening medium applied to the surface of the gear and then the pre-centering mandrel with hardness is removed from the gear by a press.

The German utility model DE-U-296 08 569 explains a hardening device for ring-shaped workpieces placed in a carrier plate Magazines are stacked on top of each other. For quenching hot workpieces the carrier plate with the magazines are firmly mounted in an oil bath Dome lowered into the openings of the stacked during lowering Penetrate workpieces. A squeezing device is also provided, which After hardening, press the mandrel out of the workpieces in the hardening oil bath.

If a cold gas stream is used as the quenching medium, one is required gas-tight chamber, roughly of the type described in German patent 100 05 969 for a shaft straightening and hardening machine completely enclosed by the chamber is known.

For cold gas quenching of relatively small workpieces, such as those used as sliding sleeves a chamber is required, the size of which is much smaller in itself can be as such in which waves can be quenched. On the other hand, the dome squeezing device requires a considerable chamber size and special measures on the squeezing device, which corresponding effort means and is therefore disadvantageous. Quenching chambers are known in which hot gear wheels brought up from a carburizing furnace are freely deposited and cold gas can be exposed to high pressure. A significant proportion of Components quenched in this way shows a distortion that is a predetermined Tolerance exceeds.

The invention is therefore based on the object, the hardening of the beginning to improve the workpieces mentioned by cold gas quenching.

To this end, the invention provides a method according to claim 1 and a Device according to claim 7 before. The invention has the advantage that ring-shaped workpieces with high precision due to the fact that compared to oil hardened cold gas quenching which is more environmentally friendly and easier to use can be, with a post-treatment in the form of a compensation unwanted distortion of the workpieces can be eliminated. In addition, the Cold gas chamber to be only as large as the size of the or Workpieces is specified because the extensive mandrel pressing and the Preparation of the pressed mandrels for the reception of hot workpieces be carried out outside the cold gas chamber, the mandrel squeezing device unaffected by damaging influences of the cold gas pressure remains. The number of workpieces that can be quenched per unit of time is determined by the Invention does not affect the mandrel squeezing and preparation of new mandrels takes less time than is required to quench the workpieces.

Figur 1 und 3 eine schematische Darstellung zur Erläuterung des Härteverfahrens mit einem Kaltgasstrom;

Figur 3 eine schematische Draufsicht auf einen Riegel;

Figur 4 einen Vertikalschnitt durch sowie eine Draufsicht auf ein zu härtendes Werkstück;

Figur 5 eine Seitenansicht sowie eine Draufsicht auf einen zur Aufnahme von übereinander gestapelten Werkstücken geeigneten Korb;

Figur 6 eine Draufsicht auf einen Rost, auf welchem Körbe abgestellt werden können; und

Figuren 7 und 8 schematische Vertikalschnitte durch eine andere Ausführungsform der Erfindung.

Further advantageous embodiments of the invention are specified in the subclaims and are apparent from the following description of an embodiment of the invention with reference to the accompanying drawings. Show it:

Figures 1 and 3 is a schematic representation for explaining the hardening process with a cold gas stream;

Figure 3 is a schematic plan view of a latch;

FIG. 4 shows a vertical section through and a top view of a workpiece to be hardened;

FIG. 5 shows a side view and a top view of a basket suitable for receiving workpieces stacked one above the other;

Figure 6 is a plan view of a grate on which baskets can be placed; and

Figures 7 and 8 are schematic vertical sections through another embodiment of the invention.

With the hardening device explained in FIGS. 1 and 2, hot, annular workpieces 10 (Figure 5) are quenched, the present Example sliding sleeves with an internal toothing 2 and an outer circumferential Ring groove 4 and an outer and inner circular periphery for vehicle transmissions are.

The hardening device essentially has a quenching chamber 20 with a upper loading door 22 and an opposite lower removal door 24, a plurality of domes 30 standing on a carrier plate 35 and an ejection device 40, 45, the latter outside the quench chamber 20 next to the Removal door 24 is arranged. Of course, the removal door 24 can also be located on the same side of the quench chamber 20 as that Loading door 22, but below it in the example shown. Further comes into consideration, the removal door 24 at the same height as the loading door 22 and compared to the same at the quench chamber 20 from below to provide explanatory reasons. A first transfer unit is not shown, which each place a set of several workpieces 10 in the quenching chamber 20 introduces through the loading door 22. Another is not shown second transfer unit, the quenched workpieces 10 from the Quenching chamber 20 is removed through the removal door 24 into the work area the ejector 40, 45 brings and a new set of domes 30 into the Quench chamber enters through the removal door 24. The first and the second Transfer units can each have a manipulator with the required degrees of freedom for the respective manipulator arm.

A group of nine similar workpieces 10, 11, 12, 13, 14, 15, 16, 17, 18 are in a different location, not shown here, concentrically one above the other in one Basket 60 (Figure 6) stacked, the bottom flange 62 of which is circular in plan view the concentric, similar top chord 64 over four vertical, circumferential directions narrow posts 61, 63, 65, 67 is firmly connected. The vertical Inner edges 66, 68, 69, 70 of the posts 61, 63, 65, 67 affect an imaginary one horizontal circle, the radius of which is only slightly larger than the largest outer radius of each workpiece 10. Furthermore, on each post in the vicinity of the lower flange 62 formed a radially inwardly projecting nose that for the posts 61 and 65th are denoted by 71 and 75. Therefore, the cold workpieces 10 from the Side of the upper belt 64 are introduced into the basket 60 so that they according Figure 1 are concentric and horizontal and spaced one above the other and to be held by the noses.

A grate 50 is used for the joint transfer of several baskets 72, 73, 74 (Figure 6), which in a framework eight similar recordings 52 for each has a basket. It is understood that each basket 60 is near the bottom End of each post 61, 63, 65, 67 pointing radially outward, not shown Has protrusions, the vertical insertion of the baskets 60 in one of the receptacles 52 allow such that the baskets 60 flush with the bottom of the bottom Rust 50 ends, as shown in Figures 1 and 2.

Each of the three cylindrical domes 31, 32, 33 shown sits with its lower one End in a through hole 36, 37, 38 of the support plate 35 and rests according to Figure 1 on a bolt 39, which is not shown under the support plate 35 is slidably mounted between two positions. The closed position, in which the through holes 36, 37, 38 of the bolt 39 at least 1 and 3 and the open position, in FIG. 2 shows which latch 39 releases through holes 36, 37, 38. The one protruding from the through bores 36, 37, 38 immediately upwards Section of each dome 31, 32, 33 is narrow of four in the circumferential direction equally spaced, equally high and upright trestles surrounded, which are designated for the mandrel 31 with 81, 82. The trestles rise from a flat ring flange surrounding the associated mandrel, which is screwed onto the top of the carrier plate 35.

The ejection device 40, 45 shown schematically in FIG. 2 is located outside the quench chamber 20 next to the removal door 24 and has one upper part 40 and a lower part 45, which are spaced vertically in such a way that carrier plate 35 with bars 39, domes 30 and baskets 60 place between them can find. The upper part 40 has three drives, not shown, vertically movable upper punch 41, 42, 43 and the lower part 45 includes correspondingly aligned with the upper punches 41, 42, 43 and not Drives shown vertically movable lower punch 46, 47, 48. In the by Stops not shown defined target position shown in Figure 2 Carrier plate 35 aligns an upper punch and a lower punch with each mandrel Stamp and the associated through opening in the carrier plate 35.

After the arrangement of the receptacles 52 in the grate 50, the three are in the Figures side by side spines and associated through holes and stamp not in the same plane, rather the middle thorn lies with related components behind the paper plane.

The method for hardening or quenching the workpieces 10 with the one described Hardening is carried out as follows. The hardening device is For example, assigned a carburizing furnace, which is a rotary hearth furnace or can generally be a heat treatment furnace. There may be rust in the oven 50 with a number of baskets loaded with workpieces 10. Is the Carburization time has elapsed, the first transfer unit pulls the grate 50 out of the Carburizing furnace and sets it through the open feed door 22 in the Quenching chamber 20 holding arms of the first transfer unit are controlled so that the grate 50 is guided over the mandrels 31, 32, 33 and placed on the carrier plate 35, for example, the mandrel 31 is centered in the stack accommodated by the basket 72 of workpieces 10 .. 18 penetrates. There are several for this weaning Possibilities: In the quenching chamber 20, the carrier plate with a Be coupled lifting device, which lifts the carrier plate so far that the Insert the mandrels into the baskets 60 on the grid 50 from below until the carrier plate 35 frames the grate 50 from below. The removal door 24 is then opposite at the top the loading door 22 on the quench chamber 20. Alternatively, be provided that the loading door 24 instead of on one side of the Quench chamber 20 is formed on its top 25. A not shown The crane can remove the grate from the transfer unit and move it through the open one Lower the loading door into the interior of the quenching chamber until the Grate 50 is seated on the carrier plate 35.

The position of the mandrels 30 on the carrier plate 35 corresponds exactly to the position of the Recordings 52 of the grate 50 so that when lowering or lowering the grate 50 or raising the carrier plate 35 by the lifting device of each mandrel 30 aligned with exactly one basket 60. Because the outside diameter of the mandrels 30 is somewhat is smaller than the smallest inside diameter of the hot workpieces 10, specifically by an amount that was expected during the quenching of the workpieces 10 corresponds to radial shrinkage of the workpieces, all hot workpieces one basket each over the associated mandrel until the bottom Workpiece of each basket rests on the support blocks 81, 82. The trestles 81, 82 are axially higher than the lugs 71, 75 around the bottom workpiece 10 to raise the area of the lower flange 62. Are the lugs 71, 75 corresponding Formed high on the post 61, the support blocks can be omitted without replacement.

Then the loading door 22 and the removal door 24 are closed and in the quench chamber 20 becomes an inert gas such as nitrogen high pressure of about 20 bar initiated. That in the quenching chamber 20, for example Cold gas circulated according to arrows 83, 84 (FIG. 8), which approximately before the introduction Has room temperature, the hot baskets 60 and those in them stacked workpieces 10 from the outside. The heated gas from the quenching chamber the heat carried by the gas is transferred via a heat exchanger withdrawn, after which the gas is returned to the quenching chamber. The hot workpieces are quenched in this way and shrink onto the Thorn 30 on. Due to this shrinking, the dimensional accuracy of the cold Workpieces 10 ensured.

If the workpieces 10 have cooled, the removal door 24 is opened and the Carrier plate 35 with latch 39 and the domes and baskets with workpieces from the second transfer unit from the quenching chamber 20 laterally and in the position shown in Figure 2 between the upper part 40 and the brought lower part 45 of the ejector. The latch 39 is in his 2 moved relative to the support plate 35, the Mandrels 31, 32, 33 through the shrunk-on workpieces in the left in Figure 2 shown unchanged position are held. Then the drives for the upper punches 41, 42, 43 and the drives for the lower punches 46, 47, 48 accordingly, that is activated in opposite directions, so that the upper stamp Can eject domes from the workpieces downwards, as in Figure 2 on the right Hand is indicated. Of course, everyone has the upper and lower stamps a smaller outside diameter than the mandrels.

After reversing the drives for the upper punches, these are turned upwards pulled out the workpieces so that the resting on the support plate 35 Grate 50 is lifted off by a manipulator, crane or the like and becomes one can be brought to another job where the quenched Workpieces 10 can be removed from the baskets 60. After removal the grate 50, the drives of the lower punch 46, 47, 48 are activated so that these stamp the domes 31, 32, 33 resting on them back into the Drive through holes in the carrier plate 35. Afterwards Moving the bolt 39 into the closed position will be the lower stamp moved down by the strength of the bolt 39 so that the support plate 35 with their domes for insertion into the quenching chamber 20 through the second Transfer unit is ready.

FIGS. 7 and 8, in which the quenching chamber 20 is only indicated, illustrate a quenching process that is relative to that described above something is changed. The domes 31, 32, 33 are by hollow domes 131, 132, 133 and the carrier plate 35 which is closed except for the through bores 36, 37, 38 is replaced by a grate carrier 135.

Since all mandrels 130 are structurally the same, only dome 131 is described in more detail. The mandrel 131 has a central axial inner channel 134, which not only how shown, is open at the top but can also be open at the bottom. The cold compressed gas therefore flows through the mandrel 131 inside and not only ensures its cooling, but also indirectly for quenching the workpieces on their inner edge, So, for example, on the internal toothing 2, if there is one. Quenching the workpieces on their inner edges becomes even more effective if the jacket 136 of the mandrel 131 with several, with the inner channel 134 communicating radial bores, two of which are provided with 137, 138 are designated. Especially if, as shown, the inner channel 134 below is closed or at least narrowed, cold compressed gas flows through the Radial bores 137, 138, which act as nozzles, directly against the inner edge of the workpieces. The radial bores are circumferential over the jacket 136 equally distributed and vertically spaced in several rows. each Row of radial holes is designed so that the associated radial holes aim approximately at the center of the respective workpiece.

The grate carrier 135 has in addition to the through opening 139 for receiving the lower end of the cathedral 131 several openings 141, 142, 143, their number and shape of the design of the grate 50 is the same. This will make a better one Vertical flow of the cold gas on the baskets and the outside of the Workpieces reached. Not shown is a grate bar, which the function of Riegel's 39 takes over and like the latter between an open position and one Closed position is slidable below the grate support. The rust bar has several openings, their arrangement and shape of the openings 141, 142, 143 of the grate carrier 135 are the same and in their closed position they are the same aligned.

The invention is not based on the numbers mentioned above one another in each Basket stacked workpieces, on the number of baskets provided, on the explained design and number of receptacles 52 in the grate 50 limited. The invention is also applicable to the quenching of a single one Workpiece that is held in a basket and is placed over a mandrel.

Claims (15)

Hardening process for hot annular workpieces such as sliding sleeves, with a cold quenching agent, in which the workpieces are placed over at least one fixed mandrel and exposed to the quenching agent and the mandrel is ejected from the workpieces after quenching, characterized in that the workpieces are in a quenching chamber be charged with cold gas and the dome is expelled outside the quenching chamber. A method according to claim 1, characterized in that the cold gas is supplied to the quenching chamber under high pressure. Method according to Claim 1 or 2, characterized in that cold gas is applied to the inner edge of the workpieces in the quenching chamber. A method according to claim 3, characterized in that heat is removed from the workpieces by the hollow mandrel through which the cold gas flows. Method according to Claim 3 or 4, characterized in that cold gas is applied to the inner edge of the workpiece from perforations in the mandrel wall. Method according to one of the preceding claims, characterized in that the mandrel is returned to the quenching chamber after it has been ejected from the workpieces. Device for carrying out the method according to one of the preceding claims with a device for feeding and fitting the hot workpieces (10) over a temporarily stationary mandrel (30; 130), and with a mandrel ejection device (40, 45), characterized in that in a quenching chamber (20) which can be filled with cold gas, the mandrel is kept ready for fitting the workpieces and the mandrel ejection device (40, 45) is arranged outside the quenching chamber (20). Apparatus according to claim 7, characterized in that several workpieces (10, ..., 18) are stacked one above the other in at least one basket (72, 73, 74) in axial alignment. Apparatus according to claim 8, characterized in that each basket is held in a receptacle (52) of a grate (50). Apparatus according to claim 8 or 9, characterized in that for each basket one mandrel (31, 32, 33; 131, 132, 133) is arranged on a carrier plate (35, 135) in such a way that each mandrel is pushed through the ejection device (40 , 45) can be ejected from the cold shrunk workpieces. Device according to one of claims 7 to 10, characterized in that the mandrels are hollow mandrels (131, 132, 133) each with a central axial channel (134) for the cold gas. Device according to Claim 11, characterized in that the carrier plate (135) has openings (141, 142, 143) which correspond to openings in the grate (50). Apparatus according to claim 11 or 12, characterized in that the jacket (136) of each hollow mandrel (131) has a plurality of radial bores (137, 138) communicating with the axial channel at the level of each of the workpieces. Apparatus according to claim 13, characterized in that the perforations are arranged in a number of rows corresponding to the number of workpieces stacked in a basket. Device according to one of claims 7 to 14, characterized in that the ejection device has an upper part (40) with a plurality of upper stamps (41, 42, 43) and associated drive and a lower part (45) with a plurality of lower stamps (46, 47 , 48), the upper and lower punches being axially aligned with one another.

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