DE2821753A1 - CAMSHAFT GRINDING MACHINE - Google Patents

Description

No ckenu / ellen grinding machine

The invention relates to grinding machines for camshafts, namely those which have the following components: a frame, a clamping table for the contact strip that can be moved in a first direction on a straight slide rail of the frame, Jigs through which the contact strip is in the same Can be clamped in the direction and rotated around its axis, a support attached to the frame for the template with devices, in order to be able to clamp the original in such a way that its axis is parallel to the above-mentioned first direction and that it can be rotated about this axis, a slide for the grinding wheel and a slide for the scanning wheel which are movably attached to the frame, this second direction of movement being right-angled to the first and grinding wheel and scanning disc are rotatably arranged on axes parallel to the first direction so that they are with the grinding piece or the template can be brought into connection, devices to the carriage with the grinding wheel

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to push against the work table, a clutch won changeable Length between the support of the grinding wheel and the support of the scanner, a device to the grinding piece and template to set in synchronous rotary motion, as well as a drive for the grinding wheel.

While the workpiece and template rotate in synchronism. the grinding wheel grinds out a profile in the workpiece that corresponds to that of the template, v / eil the position of the grinding wheel is determined by the position of the scanner in relation to the original. For machines of this type, however, the template is mechanically connected directly to the workpiece in such a way that they are arranged on the same axis as an extension with the workpiece and is firmly connected to it. In general, however, engine camshafts have at least four cams to control the intake valves and four cams to control the exhaust valves, including very often an additional eccentric Cam to control the fuel pump comes. The template for grinding such shafts therefore has eight or nine cams. Come in addition, that the grinding wheel wears out relatively quickly, so that its diameter is steadily reduced, so that after a certain time the profile of the ground cams no longer lies within the permitted tolerances. To this disadvantage To compensate for this, you have to add a second set of cams on the template with a corresponding, slight change in diameter provided, to which the scanner is applied as soon as the grinding wheel reaches a predetermined degree of wear Has. However, after a further corresponding reduction in the diameter of the grinding wheel, it must be replaced. because it is practically no longer possible to use another set of cams to compensate for the wear on the template to attach. Just one more set of cams for compensation leads to the eight original cams in the

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In the example given above, eight more are added so that the template can be used without taking into account a possible control cam for the fuel pump already has 16 cams. Even in the best case, if the template does not have additional cams for Balance, it must in any case eight (bzu /. Nine with the eccentric cam) cams. However, in order for the grinding work to be carried out with the desired precision it is essential that the scanner is operated with a relatively strong force, e.g. B. 200 kg pressed against the template will. The template, on which eight or nine cams, under certain circumstances even 16 or 17, are arranged, however, is a problem as a result a predetermined minimum length. In order to withstand the bending stress on the part of the scanner, it must therefore be of a proportionate nature have a large diameter that is several times the mean diameter of the camshaft. Corresponding the scanner usually has a smaller diameter than the grinding wheel. Result from all of this that the template is a large piece, heavy, complicated and expensive to manufacture. In addition, that it is not possible to use the same template to produce camshafts that have the same profile but with the The cams for the intake valves have a slightly different angle than the cams for the exhaust valves in order to meet the requirements of engines with different properties.

Another disadvantage is that in the course of one revolution when grinding a cam, the profile of the master cam caused a change in the relative movement between the cam surface and the grinding wheel while the rotational speed remained the same of grinding wheel and workpiece fluctuates, so that the linear cutting speed of the Abrasive particles on the grinding wheel is subject to fluctuations. This fluctuation in the linear cutting speed results

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to the fact that the recut profile is not completely with the template matches. In order to eliminate this disadvantage, the rotation of the workpiece could be modulated accordingly and / or grounded without great difficulty would be possible. The rotation of the original would then have to be modulated in exactly the same way, which would lead to practically insurmountable difficulties because of the considerable average diameter of the template whose moment of inertia would oppose sudden changes in rotational speed, such as those needed to achieve a constant linear Cutting speed would be necessary.

The aim of the invention is a machine for grinding camshafts, which does not have these disadvantages of conventional machines.

According to the invention, the necessary number of cams on the template only corresponds to the number of different profiles of the camshaft to be produced regardless of the number of knobs to be produced. The profiles of the cams on the template have almost the same dimensions as those on the camshaft to be manufactured. Furthermore, the template and workpiece set in rotation by two separate, synchronizable electric motors with backlash-free reduction gears. Also owns the machine has several interchangeable tracer discs, the diameter of which is within the range of variation of the diameter of the Grinding wheel lasts with varying degrees of wear.

In the above-mentioned example of a camshaft, the template only has one cam for the intake valve, one cam for the Exhaust valve and also, if necessary, a third, eccentric cam. Under these conditions, the template is very short and can have a considerably smaller mean diameter, which in most cases corresponds to that of the

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can correspond exactly to the camshaft, so that the cams of the template have exactly the same dimensions and profiles of the corresponding Have cams of the shaft to be produced.

A first advantage of the invention therefore leads to a template which is smaller, lighter, simpler and cheaper. Since the interchangeable tracer discs continue to have the same diameter like the grinding wheels, it is possible with little effort to keep a larger number of scanners ready, so that in each case a tracer disk can be used, the diameter of which corresponds to the respective degree of wear of the grinding wheel, wherein the amount of wear and tear no longer plays a role. This leads to the workpieces being very faithful to the original.

With such a simplified template, it is essential that the template and workpiece are rotated by independent drives; because since the cams on the camshaft to be manufactured are shifted against each other by certain angles, grinding must be carried out one cam before grinding the next cam and the template be rotated relative to the workpiece by a corresponding angle. Once that is done, both engines will work for the actual grinding process operated synchronously again. This individual control of the drives for workpiece and template can can also be used to advantage to produce such shafts with the same template in which the cams for the intake valves compared to those for the exhaust valves somewhat different angle settings corresponding to the different Should have properties that the engines should have in which these camshafts are mounted; This is with conventional template grinding machines, where the templates have as many cams as the workpiece to be produced, not possible. It is even possible to provide only one template with a single cam, provided that the profiles of the

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-7575/01 Dr.W / L- - 9 - Augsburg, May 10, 1978 Inlet and outlet control cams are identical or symmetrical.

In an advantageous embodiment of the invention, the two are synchronizable electric drives of the workpiece and the template stepper motors, which without significant step loss can absorb positive or negative accelerations. This possibility is used in another feature of the invention, namely to slow down the rotational movement of the shaft when the abrasion power decreases and increases due to the shape of the cam accelerate when the abrasion performance increases due to the shape of the cam. By carefully selecting the scope and process of this Modulation of the two synchronous drive motors can be achieved that the linear cutting speed of the grinding particles remains constant on the grinding wheel. With conventional machines, where the template and workpiece remain the same Rotating speed, this is not possible because the original is much too heavy and has a mass of inertia that is much too high is equipped so that cyclical, suddenly acting changes in their rotational speed would be conceivable. However, this option is of great importance for processing and for the faithfulness of the reground profile to the original.

For a better understanding of the invention, reference is made to the following description and the accompanying drawings show by way of example and not exclusively an embodiment of a camshaft grinding machine according to the invention.

Figure 1 is a profile view of the machine in partial section.

Figure 2 shows a plan view also with partial sections.

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Figure 3 is a partial section along the line III-III according to Fig. 1 and shows the control device of the clamping table.

FIG. 4 shows in section an exchangeable clamping device for the template.

Figure 5 is a schematic of the electronic control for the drives of the template and the shaft.

Figure 6 is a plan view, partly in section, of a modification of the control for the movements of the original carrier.

FIG. 7 shows, in plan view, also with partial sections, a modification of the control for the movements of the scanner.

The camshaft grinding machine, as it is shown in its entirety in Figures 1 and 2, has essentially: One Frame 1, a clamping table 2 for clamping the to be ground Camshaft 3, a holder 4 for a group of pattern cams 5, a holder 6 for a grinding wheel 7 and a holder 0 for a scanner 9.

Table 2, i.e. the clamping table, is on two straight lines Rails 15, 16 of the frame mounted and in both directions of the double arrow f by means to be described below Movable devices. The workpiece 3 is clamped between a tip 17 and an opposing tip 10. The summit is fastened in a spindle 21, which in turn is rotatably mounted in a dock 22 which is firmly connected to the table 2 is. The counter center 18 is loaded in a tailstock 23

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that can be fixed on the table 2 at any length setting according to the length of the workpiece 3 can. The spindle 21 is set in rotary motion by a stepping motor 24, with the interposition of it a backlash-free reduction gear 25 with holier reduction, for example 50: 1 or 100: 1. The workpiece 3 is connected to the rotatable spindle 21 by any conventional device; this device is shown in FIG is shown schematically by a lathe chuck 26 with a bent pin inserted into a plate 27, the plate 27 is firmly attached to the spindle 21. The template carrier 4 is fixed and not exchangeable on the in this example Frame 1 attached. In this example 3 pattern cams 5 are provided, namely: A cam 5a, whose profile corresponds to the one the four control cams to be grinded for the intake valves 3a on the camshaft 3 coincide; a cam 5e whose profile coincides with that of the four control cams for the exhaust valves 3e; a cam 5p whose profile matches that of the eccentric cam 3p for controlling the engine's petrol pump. In other words, the template only has so many Cams on how different profiles are provided on the camshaft to be ground. The three master cams are fixed connected to a short shaft 31 which has the same diameter as the camshaft 3 and which in two on the bracket 4 mounted bearings 33 and 34 rotates. This shaft 31 can rotate in synchronism with the rotation of the camshaft 3 are offset, namely by a stepping motor 36 with the interposition of a backlash-free reduction gear 37, which has the same high reduction as the reduction gear 25, namely 50: 1 or 100: 1.

The holder 6 of the grinding wheel 7 is formed by a carriage that rests on two parallel rails 41 and 42 of the frame

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can uerden moved in the direction of the double arrow fl at right angles to the direction f of the axis dor camshaft 3. The movements of the slide are controlled by an oil pneumatic system, which has the following components: A hydraulic cylinder 45 acting in two directions, in which the connecting rod 46 is firmly connected to the slide and the cylinder body 47 is firmly connected to the frame 1 of the machine. 40 and 49 denote the openings through which the connection with a hydraulic source or the reservoir and optionally one of the two sides of the cylinder 47 can be established, depending on the direction in which the slide is to be moved. The axis of the hydraulic cylinder 45 runs parallel to the slide rails 41, 42 of the carriage 6. The grinding wheel 7 is cylindrical, it is mounted on a shaft 51 which rotates in the carriage 6, the axis direction being parallel to that of the camshaft. The grinding wheel shaft S1 is driven by an electric motor 52 which is also mounted on the slide 6 and whose i <ii'iimnncheilio 53 is connected by V-belt 54 to a gear 55 fixedly mounted on the shaft 51. In Fig. 2, the protective hood of the grinding wheel is also denoted by 57.

The carrier Π of the scanner is also formed by a carriage movable on the two slide rails 41, 42, which is connected to the grinding wheel carriage 6 by a length-adjustable connection, which in the example shown consists of a screw nut 61 and firmly connected to the grinding wheel carriage 6 consists of a screw 62 which is rotatably, but without axial play, mounted in a bore 63 of a hump 64 of the scanning carriage 8. The screw 62 runs parallel to the slide rails 41, 42 and is driven by a stepping motor 65. The scanner 9 consists of a round disk, the diameter of which corresponds exactly to that of the grinding wheel 7. Lr is mounted removable, both

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for example by means of a screw 72 on the shaft 71, which is movably rotatably mounted parallel to the axis JX of the template cam in a carriage 74, which can be moved on the carrier 8 in rails 75, IG . The direction of movement runs at right angles to that of the slide rails 41, 42. The movement is brought about by a hydraulic cylinder 78 acting on both sides, the cylinder of which is attached to the carrier 8 and the piston rod 82 of which is firmly connected to the slide 74. In this way, the slide 74 can be brought into any of the three axial positions which the scanner 9 is to assume with respect to the cam template. A resilient ball lock, identified as a whole by 84, ensures that the slide 74 is precisely positioned in each of the three positions mentioned. The longitudinal movements of the clamping table 2 are brought about by an electric motor 91 (FIGS. 1 and 3) firmly connected to the frame 1 of the machine, which drives a screw 92 running in the nut 93 attached to the table 2. The locking of the table in each of the positions , in which the grinding wheel and the cam to be machined face each other, η Tolgt via a bolt 95 connected to the piston 98 of a hydraulic cylinder 99, which optionally engages in one of the corresponding grooves 96 of an extension piece 97 connected to the table 2.

The template 5 is easily removable. One embodiment is shown in FIG. The model cams 5 A are seated here on an axis 31 A, which is connected to the output axis 35 of the reduction gear 37 is connected by a screwdriver connection without play. The axis 35 rotates in two bearings 39, 39 a, which are attached to the carrier 4. The axis 31 A rotates in two bearings 40, 40 A, which are mounted in a cylinder housing 43 are. The housing has a side opening 48 for the input of the scanner 9, which in turn is detachable in a bore

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44 of the carrier 4 is mounted coaxially to the output axis 35 of the reduction gear 37. In order to exchange the set of master _{cams 5A for} another, it is therefore sufficient to remove the carrier housing 43 and put on another housing with the desired corners in its place.

The stepping motor 24 of the workpiece 3 and the stepping motor 36 of the platen cams 5 are fed by a pulse generator 101 (FIG. 5), a pulse counter 102, a gate 103, an amplifier 104 for supplying the motor 24 and an amplifier 105 for supplying the motor 36. The axis 31 of the template cams also has a pointer 106 which, with each revolution, occurs when a scanning device connected to the counter 102 is passed; 107 a linpulr. gives. The spindle 21, which is firmly connected to the shaft 3, has at its end a further pointer 108 which successively emits one pulse per revolution to the scanners 109 a, 109 b, 109 c, 109 e, 109 η arranged around it in a star shape.

The machine works as follows: The camshaft 3 Ti ' 2) to be ground is clamped in a certain Ausqanqsbczuqsu / inkel zvi / ischen d Le! Tiller 17, 10, the corresponding cam template T> is in the holder 4 in the corresponding pulling angle brought, with the help of the motor 91, the clamping table 2 is brought into the Lacjr-, in which a first cam 3 a is located opposite the grinding wheel 7; with the aid of the hydraulic cylinder 78, the slide 74 is brought into the position in which the scanner 9 is located opposite the corresponding pattern cam 5 a. The motor 52 of the grinding wheel is switched on, the valve 40 (see also FIG. 1) in the hydraulic cylinder 45 is opened so that the scanner 9 qeqen the cam 5 a is pressed. The motor 65 is set in motion in the direction that the connection between the grinding slide 6 and the scanner carrier 8 is

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further that the grinding wheel can be inserted into the Cuts into workpiece. By supplying power to the two stepping motors 24 and 36, the shaft 3 and the cough cam 5 a set in synchronous rotary motion. The pulse generator 101 (FIG. 5) emits pulses with a frequency of 2, 3 or N values can be selected; it has facilities for accelerating and decelerating the pulse frequency, being the degree of acceleration can be adjusted. The transition from a preselected frequency F 1 to another preselected frequency F 2 takes place via this frequency accelerator on the basis of a signal emanating from the pulse counter. The characteristics of the signal give instructions to move from frequency 1 to frequency 2 as well as instructions to select the appropriate one Frequency accelerator. Every time the pulse generator 101 sends a signal to the gate 103, this signal is sent to the amplifiers 104 and 105 of the drive motors 24 for the shaft 3 and 36 for the pattern cams 5 a passed. The same signal will passed to the counter 102, which is automatically reset to zero each time it receives a pulse from the scanner 107 receives. Each time it is reset to zero, the pulse counter is incremented; every time he selected one has reached a certain value, it sends a signal to the pulse generator that triggers a change in frequency. The coincidences are selected depending on the change in the relative surface movement between the grinding wheel and workpiece, that the synchronous rotational speed of the workpiece 3 and the template 5 varies accordingly.

If the grinding of the first input cam 3 a with, as described above, constant linear cutting speed, is finished, all other input cams 3 a are ground in the same way. For this purpose, the clamping table is first used 2 moved so far that the second inlet cam 3 a of the

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Grinding wheel facing; since this is opposite to the first Cam 3 a has a different angle, the workpiece must

a corresponding angle with respect to the template cam 5 a like

be rotated. For this purpose, the gate 103 is tilted and now sends Pulses only to the amplifier 104 of the motor 24, the the workpiece rotates until a pulse indicates that said Angle is reached. The pulse is triggered by moving the pointer 108 past the scanner 109 b. Gate 103 is now fully opened again, so that a new operation for grinding a second inlet cam 3 a begin can.

In a corresponding manner, the control cams for the exhaust valves 3 e and the eccentric cam 3 ρ control of the gasoline pump ground, each of the scanner 9 opposite the corresponding pattern cams 5 e or 5 ρ is applied.

In the embodiment described above, the axial displacement between the scanner 9 and the pattern cams 5 caused by the fact that the scanner on the movable carriage 74 reindeer was. The same result can be achieved in that the document carrier 4 is moved axially and the scanner 9 is fixed is mounted. Such an embodiment is shown in FIG. The carrier 4 A of the pattern cam is here on Rails 121, 122 of the machine frame 1 attached, the rails running parallel to the axis of the shaft 31. The carrier 4 A is driven by a motor 123 mounted on the machine frame 1 via a parallel to the slide rails 122, 122 running grape spindle and a screw nut connected to the carrier 4 a moves. Through appropriate operation of the motor 123, the carrier can be displaced in such a way that one of the pattern cams 5a, 5e, or 5ρ is opposite the scanner 9 are located. Otherwise, the machine's workflow is un-

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In the embodiment of Figures 1 and 2 w; .rd the carrier of the scanner 8 is moved axially by a hydraulic cylinder 78. In Figure 7, a variant is shown in which the carriage 74 for the scanner 9 is moved in the slide rails 75, 76 with the aid of an electric motor 131, which on the carrier 8 is attached and a parallel to the slide rails rotating spindle 132 drives, which in an on Slide 74 attached nut runs. By rotating the motor in the desired direction, the carriage 74 and thus the Scanner 9 are moved in the axial direction.

The invention is of course not restricted to the exemplary embodiments described and shown in the drawings. In accordance with the area of application, it extends to numerous possible modifications that are accessible to a person skilled in the art are. For example, when grinding very small camshafts for small engines, one becomes somewhat larger sample cams that are slightly larger in size to ensure the strength required for normal functioning.

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Claims (6)

Claims [1.j Camshaft grinding machine, consisting of: A frame, a clamping table which can be moved on slide rails in a first direction, clamping devices for clamping of the workpiece in the same axial direction, wherein the workpiece is axially rotatably mounted, one on the frame attached carrier for the template, with facilities for attaching interchangeable abrasive templates that are in the same Axial direction as the workpiece are rotatably mounted, a carrier slide for the grinding wheel and a carrier slide for the scanner disc, both movable in slide rails running at right angles to the first direction, wherein the grinding wheel and the tracer wheel are rotatably mounted in axes running parallel to the first direction, and be pressed against the template or the shaft to be processed, devices to the grinding wheel against the grinding table to move, a connection between grinding wheel carrier and tracer carrier of adjustable length, a control device to change the length of this connection and devices to rotate workpiece and template in synchronous rotation to move, characterized in that the number of cams (5 a, 5 e, 5 p) on the template (5) is the same the number of different profiles of the cams (3 a, 3 e, .3 p) on the camshaft (3) and the profiles of the pattern cams 809848/0872 -7575/01 Dr.W / L- - 2 - Augsburg, May 10, 1978 (5 a, 5 e, 5 p) have approximately the same dimensions as those of the cams on the camshaft, since the devices for the synchronous rotation of the template (5) and the workpiece (3) from two separate, synchronizable electric motors (24, 36) with zero backlash reduction gear (25, 37) and that the machine has several interchangeable scanners has whose diameter is within the range of different diameters of the grinding wheel at different Degree of wear. 2. Machine according to claim 1, characterized in that the template (5) several side by side on the axis (31) arranged cams (5 a, 5 e, 5p) and either the carrier (G) of the scanner or the carrier (4) of the original a device can be moved axially so that the scanner is selectively pressed against each of the cams (5a, 5e, 5p) can. 3. Machine according to claim 1, characterized in that the drive motors (24, 36) for the shaft (3) and the template (5) are stepper motors. 4. Machine according to claim 3, characterized in that it has devices (1Ü2, 1Ü3, 106, 107, 108, 109), the speed of the two motors (24, 36) synchronously depending on the changes caused by the cam profile to modulate the relative movement between the grinding wheel and the cam surface. 5. Machine according to claim 4, characterized in that the means for modulating the speed of the Drive motors (24, 36) for the shaft (3) and the template (5) consist of a pulse counter (102) and a gate (103), the - 3 - 809848/0872 -7575/01 Dr.W / L- - 3 - Augsburg, May 10, 1978 both are connected to a pulse generator (101), a pointer (106) firmly connected to the template (5), one of the latter Pointer excited scanner (107), which is connected to the pulse counter (102), another, firmly connected to the IJelle (3) Pointer (108), which is star-shaped by scanners (109 a, 109 b, 109 n), which are excited by it and connected to the gate (103), as well as devices for decelerating and Slowing down the pulse frequency with a preselectable degree of acceleration within the pulse generator (101). 6. Machine according to claim 1, characterized in that the length-adjustable connection between the carrier (6) the grinding wheel and the carrier (8) of the scanner from one driven by an electric stepping motor (65) Screw spindle (62) which rotates in a nut (61). 809848/0872