DE3737694C1 - Method for operating an induction hardening device for crankshafts and such a device - Google Patents

Abstract

Apparatus for the low-distortion hardening of crankshafts includes a system (1) for heating and quenching a crankshaft (2), clamping heads (3,4), and a drive (8) for rotating the crankshaft around its longitudinal axis. Actuators (17) provided with pistons (16) are located at one end in a casing (10) and cooperate with stops (18) on a square spindle sleeve (12) freely mounted in needle bearings (14) to move the casing (10). A hollow spindle (11) carrying one of the clamping heads (3) is rotatably mounted in the casing (10). Thus during heating and quenching the crankshaft which is fixed at one end (9) can move freely in the axial direction so that no harding distortion takes place. <IMAGE>

Description

The invention relates to a method for operating a Induction hardening device for crankshafts, in which the Crankshaft at both ends in radially rigid axially displaceable rotatable clamping heads clamped and around their axis is rotated.

It is well known that distortion-free hardening of workpieces of whatever profile or shape is almost impossible. The cause is the result of heating Expansion occurring expansion and contraction of the Workpiece when quenching, resulting in a permanent Deformation, the default. The low warpage hardening flat workpieces, such as flat strips, succeed z. B. by Pressing the heated workpiece when quenching. A saw such firm clamping of the workpiece to be hardened experts generally see it as the optimal solution. The The dominant idea was to heat the workpiece and not giving deterrence an opportunity to Yield to deformation efforts. The fixed appeared for this Clamping the workpiece to be hardened the optimal solution, such as those used for hardening camshafts DE-OS 35 08 131 was known. The camshaft will rotatably held at both ends, of which one for clamping in the axial direction of the camshaft is movable. With this method it was not possible to the final straightening of the hardened workpiece to be able to do without. Special difficulties  prepare irregularly shaped elongated elongate during hardening Workpieces such as crankshafts, camshafts and racks, where the delay in hardness is very different, the Size of the delay in hardness is difficult to predict and for which clamping is not a useful remedy for delay in hardness creates. This is useful for crankshafts, their crank bearings should be hardened, only clamping on the pivot bearings little, because one can on the exposed crank bearings Delay in hardness occurs unhindered.

The invention is based on the task with little Effort the hardness delay of hardened in the circulation process To minimize crankshafts, so on a complex Straightening can be dispensed with.

Surprisingly, it has now been found that a Hardening that is largely free from warpage can be achieved if you have one the clamping heads of its sliding drive during the Decoupled hardening process, in one with the outside Non-contact sealing air or low inhibition via bellows sealed and against axial expansion of the Crankshaft with a coefficient of friction of less than 0.01 is stored hydrostatically or roller-guided. If then elongation of the workpiece occurs during heating, the workpiece can follow this endeavor and can as well shrink it freely when quenched, so that hardly any delay occurs.

The teaching of the invention represents a complete departure from the prevailing technical opinion so far that Avoiding hardness distortion in the workpiece To clamp in the direction. After this Proposed invention is just the opportunity for the workpiece required, the tendency to deform when heated and Giving in to deterrence.  

The practically sensible realization of the invention The solution is to turn the crankshaft around at least one of its ends with a coefficient of friction of less than 0.01 to store so low friction that they even with the occurrence of very low axial forces, like them arise from thermal expansion, move freely in the axial direction can.

In a device for the rotary hardening of crankshafts, the according to DE-AS 23 43 684 at both ends in each other opposite clamping heads rotatable about their axis are clamped, a heating and quenching device, a Drive on one of the two clamping heads for turning the clamped crankshaft around its axis, one each Clamping drive on both clamping heads and with one Sliding drive for the clamping heads compared to the Includes crankshaft for receiving the same for clamping, According to the invention, the shift drive pneumatic or hydraulic piston cylinder units exist, which are fixed at one end in a housing and at the other end with stops on one in needle bearings floating in another housing Square quill interact, in one the clamping head supporting hollow spindle is rotatably supported by the a control device actuable clamping drive means are passed coaxially. The crankshaft to be hardened becomes solid at one end, i.e. H. axially immobile clamped while the clamping head on the opposite End of the rotatably mounted crankshaft in its Is movable axially after the sliding drive is released from the clamping head.

According to a preferred embodiment of the invention the housing has little outward inhibition due to bellows be sealed.  

In the drawing, an embodiment of the Device according to the invention shown. It shows

Fig. 1 is a view of the hardening device,

Fig. 2 shows a longitudinal section of the axially movable clamping head and

Fig. 3 shows a cross section of the clamping head.

The same parts are in the different figures provided the same reference numerals.

Fig. 1 shows the entire hardening device with dash-dotted device 1 for heating and quenching the crankshaft 2 to be hardened with clamping heads 3, 4 for clamping the crankshaft 2 at opposite ends and central support 5 for the central bearing of the crankshaft 2nd The clamping of the crankshaft 2 in the clamping heads 3 and 4 is effected by controls 6 and 7 .

The crankshaft 2 rotating about its longitudinal axis during the hardening process is clamped on one side (right side in FIG. 1) in the clamping head 3 , on which the drive 8 for rotating the crankshaft 2 engages around its axis and in a housing 9 is axially fixed. The clamping head 3 , which clamps the other end of the crankshaft 2 (left side in FIG. 1), is floating in the housing 10 , that is to say axially displaceably, as can be seen in detail from FIGS. 2 and 3.

The clamping head 3 sits at the end of a tubular spindle 11 which is rotatable in a roller bearing 13 mounted in a square spindle sleeve 12 . The square quill 12 is in turn mounted axially displaceably in opposite directions in a needle bearing 14 in the housing 10 . The pull rod 15 for actuating the clamping head 3 when clamping the crankshaft 2 is guided coaxially through the spindle 11 .

Pneumatic or hydraulic piston-cylinder units 17 are mounted on one side of the rigid in the housing 10 blocks 19th The pistons 16 can be extended in the axial direction of the pivot bearing 2 until they abut stops 18 which are fastened to the square sleeve 12 .

Low-inhibition bellows 20 secure the interior of the housing 10 from contamination. Alternatively, the housing 10 can be sealed from the outside in a contactless manner by means of sealing air.

To clamp the crankshaft 2 , the clamping heads 3, 4 are fed towards the ends of the crankshaft 2 , and these are then clamped by actuating the chuck on the clamping heads 3, 4 by means of the controls 6, 7 . The adjustment of the clamping heads is effected by piston 16 of the piston-cylinder unit 17 , which exerts pressure against the stops 18 attached to the square sleeve 12 and thereby axially displaces the square sleeve 12 and with it the spindle 11 and the clamping head 3 in the housing 10 . When the crankshaft 2 is unclamped, the piston-cylinder unit 17 is actuated, which pushes the clamping head 3 away from the crankshaft 2 . By uncoupling the displacement drive for the clamping heads 3, 4 formed from the piston-cylinder units 17 after the clamping process, the prerequisite for the low-friction axial displaceability of the clamping heads 3, 4 is created.

• 1 heating and quenching device
  2 crankshaft
  3 clamping head
  4 clamping head
  5 support
  6 control
  7 control
  8 rotary drive
  9 housing
  10 housing
  11 spindle
  12 square quill
  13 rolling bearings
  14 needle bearings
  15 tie rod
  16 pistons
  17 piston-cylinder unit
  18 stop
  19 buck
  20 bellows

Claims (3)

1. A method of operating an induction hardening device for crankshafts, in which the crankshaft is clamped at both ends in radially rigid axially displaceable rotatable clamping heads and rotated about its axis, characterized in that one of the clamping heads is uncoupled from its displacement drive during the hardening process, in one after externally sealed by means of sealing air without contact or by means of bellows with little inhibition and is supported hydrostatically or roller-guided against axial expansion of the crankshaft with a coefficient of friction of less than 0.01. 2. Device for hardening crankshafts, which are clamped at both ends in mutually opposed clamping heads about their axis, with a heating and quenching device and a drive on one of the two clamping heads for rotating the clamped crankshaft about its axis, one clamping drive each two clamping heads and with a displacement drive for the clamping heads with respect to the crankshaft when receiving the same for clamping, characterized in that the displacement drive consists of pneumatic or hydraulic piston-cylinder units ( 17 ) which are fixed at one end in a housing ( 9 ) and at the other end interact with stops ( 18 ) on a square spindle sleeve ( 12 ) floating in a further housing ( 10 ) floating in needle bearings ( 14 ), in which a hollow spindle ( 11 ) carrying the clamping head ( 3 ) is rotatably supported, by a control device ( 6 ) actuatable clamping drive means ( 15 ) coaxial hi are carried out. 3. Apparatus according to claim 2, characterized in that the housing ( 10 ) is sealed by bellows ( 20 ) to the outside with little inhibition.