EP0570605B1 - Guard for planing machine - Google Patents

Abstract

The invention relates to a guard for planing machines for the jointing and surfacing of workpieces (48) made of wood, with a member for covering the cutter block (34), which member is attached to one side of the machine bed in a vertically movable manner. The cover member consists of a cover strip (30) which is mounted in a guide member in such a way as to be horizontally displaceable against a pressing force acting in the direction of a jointing stop (36). Here, the cover strip (30) has the double function of covering the cutter block in every position during jointing as well as during surfacing and at the same time of exerting a certain applied pressure to the workpiece (48) during jointing. <IMAGE>

Description

The invention relates to a protective device for planing machines for joining and dressing wooden workpieces with an organ for covering the knife shaft, which is attached to one side of the machine bed and is made of a cover strip, which acts on a support plate against one acting in the direction of a joining stop Pressure force is horizontally displaceable.

Planer protection devices are known in which the organ for covering the knife shaft is attached to a support head which is pivotally attached to one side of the machine bed via a lever linkage. For dressing workpieces, the cover element can be raised so that the workpiece can be pushed through. For joining work, the covering member is removed from the joining stop via the lever linkage, so that the workpiece can be carried out between the end of the covering member and the joining stop; a pressing force of the covering member on the workpiece is applied by hand. After the workpiece has been pushed through between the joining stop and the end of the covering member, it remains in its position remote from the joining stop, so that the part of the knife shaft which is exposed there is not covered.

A protective device of the type described at the outset is described and illustrated in US-A 1 630 671. In this known device, the cover strip is moved in the direction of the joining stop with the aid of a weight via a deflection chain. The cover strip must be set vertically so that the workpiece can be pushed through for dressing. For this purpose, an adjusting screw is provided, which clamps a vertical rod, which projects downward from the support plate, at the required height. This construction has two major disadvantages, one of which is that, depending on the distance of the cover strip above the working level, there is a risk that the operator's fingers can get between the cover strip and the knife shaft, which leads to serious cuts. In addition, a minimum height must be set before each dressing process, which is slightly larger than the height of the workpiece, which is cumbersome and time-consuming for different workpieces to be machined one after the other. In addition, due to the height difference between the top of the workpiece and the underside of the stop bar, the latter does not exert any pressure on the workpiece from above.

The subject of EP-A 85 636 is a planer protection device with a cover strip which is attached to a telescopic device with a compression spring. After each downward movement, the spring presses the cover strip back into a rest position, which is defined by the angular setting of a cam, against which a lever hinged to the cover strip strikes. The cover strip can only be raised above the set rest position, for example for dressing thicker workpieces, by rotating the stop cam. Since a free lifting of the stop bar beyond the set stop is not possible, it cannot exert any vertical pressure on the workpiece to be dressed.

The invention has for its object to provide a planer protection device in which the cover strip ensures perfect coverage of the knife shaft in any position and exerts the contact pressure required for machining in both the horizontal and vertical directions.

To solve this problem it is provided that the support plate is attached to a lifting device, which is connected to a tracking device for automatic return of the cover strip both from above and from below into an adjustable rest position above the knife shaft.

The cover strip can thus be set in a vertical rest position from which it can be freely lifted upwards in order to press its weight vertically onto the workpiece during the subsequent dressing or to offer the possibility of dressing a thicker workpiece. In addition, the cover strip can be pressed down from the selected rest position, for example by a workpiece that is pulled back over the cover strip after dressing; then it automatically returns to its rest position.

The tracking device for the vertical adjustment upwards can have, for example, a gas spring or a helical spring.

According to a further feature of the invention, four guide rollers lying opposite one another in pairs are mounted on the support plate, between which the cover strip is held displaceably in the direction of its longitudinal axis. The guide rollers ensure a tilt-free longitudinal displacement of the cover strip.

In a further development of the invention it is provided that the lifting device is connected to a weight relief device for the cover strip, so that only a fraction of the total weight has to be moved by hand when the cover strip is raised. The weight relief device can have a mainspring with adjustable preload, but it can also consist of a gas spring.

In a preferred embodiment of the invention, the lifting device has two vertical rods which are mounted in ball guide bushes attached to the carrier and are connected via a cable to the mainspring attached to the carrier for weight relief. With this solution, the ball guide bushes ensure trouble-free height adjustment of the cover strip without the risk of jamming or jamming. The mainspring for the weight relief is attached to the carrier and can be accommodated in a housing that takes up little space and enables a compact design.

In one variant, the lifting device has a slide which is mounted on guide rails attached to the carrier via guide rollers, the gas spring acting on the carrier on the one hand and on the slide on the other hand to relieve weight.

In both cases, there is the possibility of connecting the lifting device to the tracking device, which has a height-adjustable gas spring which is supported on the carrier.

In this case, the cylinder housing of the height-adjustable gas spring can be connected in an articulated manner with its upper end to a lifting lever which is pivotably mounted on the carrier and on whose free end the support plate is supported. The piston rod of this gas spring is articulated with its downward-facing end on a slide plate which is arranged in a guide rail of the carrier so as to be vertically displaceable and lockable. Such a solution makes it possible in a simple manner to adjust the rest position of the cover strip above the knife shaft, so that the required gap height remains free when dressing workpieces. After a workpiece has been pushed through, it can be pulled back by hand over the cover strip, which, in the case of heavy workpieces, is pressed down towards the knife shaft. Subsequently, the cover strip automatically returns to its previously set rest position, so that the next workpiece can be pushed through for dressing.

In a variant for the tracking device, the piston rod of the height-adjustable gas spring is supported with its downward-pointing end on the carrier, while the housing of the gas spring is displaceable relative to the carriage and can be fixed thereon.

Characterized in that according to the invention a support plate is provided for the guide member of the cover strip, it is possible to attach it to a swivel arm which serves as a lifting device and is attached to one side of the machine bed. This simplifies the conversion of planing machines already in use that are already equipped with a swivel arm.

In this solution, it is advantageous if the swivel arm receives the gas spring for generating the pressing force, which has a deflecting roller for a cable at the free end of its piston rod, which is guided over other deflecting pulleys in the manner of a pulley block and fastened on the one hand to the swivel arm and on the other hand to the cover strip is. With this measure, it is possible to use a gas spring, the relatively small stroke of which generates a multiple of the displacement path for the cover strip due to the translation of the pulley block.

In a further development of the invention it is provided that the free end of the cover strip pointing towards the joining stop carries a pressure shoe from which an inlet beak protrudes which lies in a plane running parallel to the work table and forms an acute angle with the joining stop. The inlet beak facilitates the feeding of the workpiece when joining, since this gradually moves the pressure shoe and with it the cover strip against the pressing force away from the joining stop until the required gap width for pushing through the workpiece is reached.

It is advantageous if the inlet beak in the pressure shoe can be pivoted about a horizontal axis lying transverse to the longitudinal axis of the cover strip into a position rotated by 90, in which it protrudes upward from the work table. In this position, rotated by 90, the upward-inclined inlet beak facilitates the feeding of workpieces for dressing work. When feeding, the workpieces press against the underside of the upward-facing infeed beak and raise it, and with it the cover strip connected to it, until the required gap height for pushing through the workpiece is reached.

According to another feature of the invention, the cover strip is interrupted in its central region by a hinge, by means of which the rear part of the cover strip pointing away from the joining stop can be folded down. It is advantageous if the hinge has a locking element for locking the rear part of the cover strip in a horizontal position in alignment with the front part.

With this training there is no need to have cover strips of different lengths depending on the position of the joining stop for different workpiece work and to replace them as required, because for dressing narrow workpieces, the rear part of the cover strip can be folded down in order to dress wide workpieces again to pivot upwards and lock with the front part in a horizontal position. Only a few steps are necessary for this, without the need to use tools.

A drive spring, a gas spring or an electronically controlled motor can be provided to generate the pressure force on the cover strip.

When a drive spring is used to generate the pressing force, it is advantageously attached to the support plate and connected to the cover strip via a cable. It is advantageous if the cover strip carries a lockable stop element which is displaceable in the direction of its longitudinal axis and on which the cable pull acts. The horizontal adjustment path of the stop bar in the direction of the joining stop can be adjusted via the stop element, both when using only the front partial area of the cover bar with the rear part folded down and over the entire area of the cover bar. In this way, when performing dressing work, it is possible to leave a small gap between the free end of the cover strip and the joining stop, so that frictional contact between the end of the covering strip and the joining stop is avoided.

• Figur 1 die Draufsicht auf eine erste Ausführungsform einer Schutzeinrichtung gemäß der Erfindung,
• Figur 2 einen Querschnitt in der Ebene 11-11 der Figur 1,
• Figur 3 eine Ansicht in Richtung des Pfeiles 111 der Figur 1,
• Figur 4 die vergrößerte Draufsicht des an einem Fügeanschlag anliegenden Endes der Abdeckleiste beim Fügen eines Werkstücks,
• Figur 5 die Ansicht in Richtung des Pfeiles V der Figur 4,
• Figur 6 eine der Figur 5 entsprechende Darstellung mit gedrehtem Einlaufschnabel zu Beginn eines Abrichtvorganges,
• Figur 7 eine Draufsicht in Richtung des Pfeiles VII der Figur 6,
• Figur 8 einen vergrößerten Ausschnitt aus Figur 3 zur Darstellung der Hubeinrichtung mit Gewichtsentlastungseinrichtung,
• Figur 9 einen Vertikalschnitt in der Ebene IX-IX der Figur 8,
• Figur 10 in vergrößerter Darstellung einen teilweise geschnittenen Ausschnitt aus Figur 2,
• Figur 11 einen Vertikalschnitt durch das Anschlagelement in der Ebene XI-XI der Figur 1,
• Figur 12 eine der Figur 11 entsprechende Darstellung des Anschlagelementes bei geöffneten Klemmbacken,
• Figur 13 eine vergrößerte Draufsicht auf den mittleren Teil der Abdeckleiste zur Darstellung des Schnarniers,
• Figur 14 einen Vertikalschnitt in der Ebene XIV-XIV der Figur 13,
• Figur 15 eine der Figur 14 entsprechende Darstellung der Abdeckleiste mit nach unten abgeklapptem hinteren Teil,
• Figur 16 die Draufsicht auf eine Variante der Schutzeinrichtung,
• Figur 17 die Seitenansicht in Richtung des Pfeiles XVII der Figur 16,
• Figur 18 eine Ansicht in Richtung des Pfeiles XVIII der Figur 17,
• Figur 19 einen Vertikalschnitt in der Ebene XIX-XIX der Figur 17,
• Figur 20 einen teilweise geschnittenen Ausschnitt aus der Figur 16 in vergrößertem Maßstab,
• Figur 21 die Draufsicht auf eine weitere Variante der Schutzeinrichtung,
• Figur 22 die Seitenansicht in Richtung des Pfeiles XXII der Figur 21,
• Figur 23 in vergrößertem Maßstab einen Querschnitt in der Ebene XXIII-XXIII der Figur 22,
• Figur 24 einen Querschnitt in der Ebene XXIV-XXIV der Figur 22,
• Figur 25 in vergrößertem Maßstab einen Querschnitt in der Ebene XXV-XXV der Figur 22,
• Figur 26 in vergrößertem Maßstab einen Vertikalschnitt in der Ebene XXVI-XXVI der Figuren 21 und 25,
• Figur 27 im Ausschnitt einen Horizontalschnitt der Abdeckleiste in der Ebene XXVII-XXVII der
• Figur 28,
• Figur 28 in vergrößertem Maßstab einen Querschnitt der Abdeckleiste in der Ebene XXVIII-XXVIII der Figur 21 und
• Figur 29 eine schematische Draufsicht auf eine weitere Variante der Erfindung.

Further features and advantages of the invention emerge from the patent claims and from the following description of exemplary embodiments which are illustrated in the drawing. Show it:

• FIG. 1 shows the top view of a first embodiment of a protective device according to the invention,
• FIG. 2 shows a cross section in the plane 11-11 of FIG. 1,
• FIG. 3 shows a view in the direction of arrow 111 in FIG. 1,
• FIG. 4 shows the enlarged top view of the end of the cover strip resting against a joining stop when joining a workpiece,
• 5 shows the view in the direction of arrow V of FIG. 4,
• FIG. 6 shows a representation corresponding to FIG. 5 with the inlet beak turned at the beginning of a dressing process,
• FIG. 7 shows a plan view in the direction of arrow VII in FIG. 6,
• FIG. 8 shows an enlarged detail from FIG. 3 to show the lifting device with weight relief device,
• FIG. 9 shows a vertical section in the plane IX-IX of FIG. 8,
• FIG. 10 shows an enlarged illustration of a partially cut section from FIG. 2,
• FIG. 11 shows a vertical section through the stop element in the plane XI-XI of FIG. 1,
• FIG. 12 shows a representation of the stop element corresponding to FIG. 11 when the jaws are open,
• FIG. 13 shows an enlarged top view of the middle part of the cover strip to show the hinge,
• FIG. 14 shows a vertical section in the plane XIV-XIV of FIG. 13,
• FIG. 15 shows a representation of the cover strip corresponding to FIG. 14 with the rear part folded down,
• FIG. 16 shows the top view of a variant of the protective device,
• FIG. 17 shows the side view in the direction of arrow XVII in FIG. 16,
• FIG. 18 is a view in the direction of arrow XVIII in FIG. 17,
• FIG. 19 shows a vertical section in the plane XIX-XIX of FIG. 17,
• FIG. 20 shows a partially cut section from FIG. 16 on an enlarged scale,
• FIG. 21 shows the top view of a further variant of the protective device,
• FIG. 22 shows the side view in the direction of arrow XXII in FIG. 21,
• FIG. 23 shows, on an enlarged scale, a cross section in the plane XXIII-XXIII of FIG. 22,
• FIG. 24 shows a cross section in the plane XXIV-XXIV of FIG. 22,
• FIG. 25 shows, on an enlarged scale, a cross section in the plane XXV-XXV of FIG. 22,
• FIG. 26 shows, on an enlarged scale, a vertical section in the plane XXVI-XXVI of FIGS. 21 and 25,
• Figure 27 in a detail a horizontal section of the cover strip in the plane XXVII-XXVII
• Figure 28,
• 28 shows, on an enlarged scale, a cross section of the cover strip in the plane XXVIII-XXVIII of FIGS. 21 and
• Figure 29 is a schematic plan view of a further variant of the invention.

Figure 1 shows a top view of the preferred embodiment of the protective device according to the invention. A carrier 14 is fastened to the longitudinal side 10 of the machine bed of a planing machine facing the operator, the work table of which is indicated by 12. On a side wall 16 of the carrier 14, which protrudes at right angles from the longitudinal side 10, a lifting device 18 is attached, which in the exemplary embodiment of FIGS. 1 to 15 has two vertical rods 20 which are connected to one another at the lower end by a horizontal plate 22. The two rods 20 are vertically displaceably mounted in ball guide bushes 24 which are fastened to the side wall 16 of the carrier 14. A horizontal support plate 26 is fastened to the upper ends of the two rods 20 and is thus part of the lifting device 18 is.

On the support plate 26 are four pairs of guide rollers 28 opposite each other with a vertical axis of rotation, between which a cover strip 30 is held in the direction of its longitudinal axis 32. The arrangement is such that the cover strip 30 lies in a manner known per se centrally over a knife shaft 34, which is indicated in FIG. 6. The longitudinal axis 32 of the cover strip 30 runs parallel to the axis of rotation of the cutter shaft 34.

The free end of the cover strip 30 (see FIG. 4) facing a joining stop 36 of the planing machine carries a pressure shoe 38. An inlet spout 40 protrudes from the pressure shoe 38, which in the position shown in FIGS Workbench 12 is level and forms an acute angle a with the joining stop 36. As can further be seen from FIG. 4, the inlet beak 40 is pivotably mounted in the pressure shoe 38 by means of a bolt 42 about a horizontal axis 44 lying transversely to the longitudinal axis 32 of the cover strip 30. The inlet beak 40 has a handle recess 46 so that it can be swiveled by hand from its joining position shown in FIGS. 4 and 5 against the force of a compression spring 50 by 90 _° into the position of FIGS. 6 and 7. In both positions, the inlet beak 40 is locked on the pressure shoe 38 by a not shown locking element. In the position of FIGS. 6 and 7, the inlet beak 40 protrudes upward from the work table 12 and forms the angle a with it, so that a workpiece 46 can be inserted for dressing.

The inlet beak 40 consists of a material that is harder than the material of the pressure shoe 38. This ensures that premature wear of the inlet beak 40 is prevented, while the sliding movements on the pressure shoe 38 are favored due to the softer material.

When joining workpieces 46, the cover strip 30 exerts a pressing force on the workpiece 46 via its pressure shoe 38 and thereby presses it against the joining stop 36. The pressing force is generated by a drive spring 52, which has the shape of a spiral spring. As FIG. 10 shows, the drive spring 52 is fastened at one end to a bolt 54 which is screwed to the support plate 26 below the cover strip 30. The other end of the mainspring 52 is attached to the inside of a cylindrical housing 56 which can be rotated to adjust the bias of the mainspring 52. On the outer circumference of the housing 56, an annular groove 58 is machined, in which a cable 60 is wound, the free end of which, according to FIG. 1, is guided centrally via a deflection roller 62 to a stop element 64, to which it is attached.

As shown in FIGS. 11 and 12, the stop element 64 consists of two clamping jaws 66 which grip around the cover strip 30 on its two longitudinal sides. The two clamping jaws 66 sit on a common support bolt 68, the right end of which is designed as a handle 70 in FIGS. 11 and 12. An arm 72 of a release lever 74 engages between the two opposite ends of the clamping jaws 66; the arm 72 is pivotally mounted on the support bolt 68 by means of a pin 76. If the release lever 74 is pressed by hand against the handle 70 from the clamping position of the stop element 64 shown in FIG. 11, the arm 72 according to FIG. 12 spreads the two clamping jaws 66 apart against the force of spring elements 78 which act on the two ends of the support bolt 68 are placed so that the entire stop element 64 can be moved by hand on the cover strip 30. The cable 60 is taken along. When the desired position of the stop element 64 on the cover strip 30 is reached, the release lever 74 is released again, so that the stop element 64 is clamped in the new position on the cover strip 30. The cover strip 30 is pulled into the selected position via the cable pull 60 and the drive spring 52, in which the stop element 64 bears against the support plate 26.

The drive spring 52 and the adjustable stop element 64 cause the cover strip 30 to be automatically moved back into the position in which the knife shaft 34 is covered to the maximum after each horizontal displacement when joining. At the same time, the mainspring 52 takes on the task of exerting the required pressing force on the workpiece 46 in the direction of the joining stop 36.

FIGS. 13 to 15 show a cutout of the central area of the cover strip 30, which is interrupted here by a hinge 80. The rear part 30 "of the cover strip 30 pointing away from the joining stop 36 can be folded downward via this hinge 80 (cf. FIG. 15). For this purpose, a locking element 82 is located on the rear part 30" of the cover strip 30 in the direction of the longitudinal axis 32 the cover strip 30 slidably mounted against the force of a compression spring 84. In order to be able to move the locking element 82 without the aid of tools, it has a depression 86 into which a finger can engage. The end of the locking member 82 facing the front part 30 'of the cover strip 30 is designed as a nose 88 which engages over an inclined surface 90 at the opposite end of the front part 30' of the cover strip 30 when the rear part 30 "is locked to the front part 30 ' (see figure 14).

The two-part design of the cover strip 30 has the advantage that the rear part 30 "can be folded down if only a narrow working area has to be covered over the knife shaft 34. This prevents the rear part 30" of the cover strip 30 from being too wide protrudes beyond the work table 12. If a wider working area has to be covered over the knife shaft 34, the rear part 30 "is folded up and locked in alignment with the front part 30 'by means of the locking element 82. The stop element 64 shown in FIGS. 11 and 12 can then also be used in the rear part 30 "of the cover strip 30 are moved.

Of course, there is the possibility of designing the divided cover strip 30 differently in its hinge area. For example, the hinge can be constructed in such a way that it can be removed, for example to assemble the cover strip 30 from more than two parts of the same length, which are identical to one another. There is also the possibility of providing an identical hinge construction at the front end of the cover strip 30 in order to fasten the pressure shoe 38 there.

As already explained, the cover strip 30 can be raised a certain dimension, generally 75 mm, above the work table 12, which is indicated by dash-dotted lines in FIG. 3. In order to facilitate this manual lifting, a weight relief device is provided. In this exemplary embodiment, as shown in FIGS. 1 to 3 and 8 and 9, this consists of a drive spring 92 designed in the manner of a spiral spring, the inner end of which is fastened to a bolt 94 which is attached in a cylindrical housing part 96 of the wall 16. The housing part 96 is closed by a cover 98 and lies between the two vertical rods 20. The outer end of the mainspring 92 is fastened in a housing 100 which can be rotated to adjust the spring preload and thus the weight relief. On the outer circumference of the cylindrical housing 100 there is an annular groove 102, in which a cable 104 is wound, the free end of which is guided centrally via a deflection roller 106 mounted on the side wall 16 of the carrier 14 to the plate 22, which is the lower ends of the two rods 20 connects together. The end of the cable pull 104 is fixed there.

When the support plate 26 with the cover strip 30 and the vertical rods 20 is moved upward, the force of the drive spring 92 counteracts the total weight of the components mentioned and thereby supports the lifting work, which requires only a small amount of force.

As can be seen from FIGS. 1 to 3, a lifting lever 110, acting as a reinforcement lever, is pivotably mounted on the carrier 14 via a bolt 108, which lever swivels in the vicinity of its horizontal pivot axis formed by the bolt 108 about an axis 112 parallel to this upper end of the housing 114 is connected to a gas spring 116. At the free end of the lifting lever 110, a roller 118 is attached which, as shown in FIGS. 1 and 2, projects laterally from the lifting lever 110 and is supported on the underside of the support plate 26. The lower end of the piston rod 120 of the gas spring 116 is articulated on a lateral projection 122 of a sliding plate 124 which extends in the vertical direction and is arranged so as to be vertically displaceable in a guide rail 126 of the carrier 14. The height-adjustable sliding plate 124 can be clamped in its guide rail 126, for which purpose a clamping lever 128 is used, the threaded bolt of which extends through vertical elongated holes 130 in the guide rail 126.

A blind hole 132, into which a compression spring 134 is inserted, is machined into the lower end of the sliding plate 124. The compression spring 134 is placed on a vertical pin 136 and is supported with its lower end on the carrier 14.

The gas spring 116 is part of a tracking device for the lifting device 18, which allows the support plate 26 and thus the cover strip 30 to be adjusted vertically by 75 mm. If dressing work is to be carried out, the cover strip 30 can be raised to a desired height by hand. When the clamping lever 128 is released, the compression spring 134 presses the slide plate 124 upward, so that the gas spring 116 is carried along. The housing 114 presses against the underside of the support plate 26 via the lifting lever 110 and the roller 118, the piston rod 120 of the gas spring 116 being fully extended. In the desired height position of the support plate 26, the slide plate 124 is then blocked in the guide rail 126 by means of the clamping lever 128. Series parts or larger workpieces can then be dressed without the support plate 26 with the cover strip 30 having to be raised completely each time. Rather, it is sufficient to raise it by a small amount, which ensures that when the workpiece is subsequently pushed through, the cover strip 30 exerts a certain contact pressure on the workpiece due to its own weight. After the workpiece has been pushed through, it can be withdrawn again via the cover strip 30, the weight of the workpiece pressing the cover strip 30 downward against the force of the gas spring 116. As soon as the workpiece has been pulled over the cover strip 30, the gas spring 116 presses the support plate 26 with the cover strip 30 upwards again via the lifting lever 110, so that the next workpiece can be dressed.

In the exemplary embodiment in FIGS. 16 to 20, the lifting device for the support plate 26 and the cover strip 30 which can be moved thereon consists of a slide 138 which is connected to the support plate 26 via a bracket 140. The carriage 138 is mounted on four vertically arranged guide rollers 142 on a vertically arranged guide rail 144, which can be fastened to the longitudinal side 10 of the work table 12 via a spacer plate 146 forming the carrier 14. A handle 148 protrudes laterally from the carriage 138, which allows the support plate 26 with the cover strip 30 to be lifted or lowered with ease. The weight relief device in this variant of the invention has no mainspring, but a gas spring 150, the piston rod of which is attached with its lower end to the guide rail 144, while the upper end of the housing of the gas spring 150 is connected to the slide 138.

The gas spring 116, which is part of the tracking device for the lifting device 18, is accommodated between the guide rail 144 and the slide 138 in addition to the gas spring 150. The piston rod 120 of this gas spring 116 is supported with its downward-facing end on a stop 152 which protrudes from the guide rail 144. The housing 114 of the gas spring 116 is freely movable in height and can be adjusted relative to the slide 138. As in the exemplary embodiment described above, the support plate 26 with the cover strip 30 mounted thereon can also be raised in order to carry out dressing work. For this purpose, the slide 138 is moved vertically by means of the handle 148, in order then to be fixed in the desired position on the housing 114 of the gas spring 116. A cuff 154 which surrounds the housing 114 is used for this purpose. About two small balls 156, which can be adjusted by inclined surfaces 158 of an adjusting bolt 160, the sleeve 154 can be moved radially against the force of disc springs 162 to the housing 114 of the gas spring 116, so that it is vertically movable. In order to bring about this release position, a clamping lever 164 is used, which lies below the handle 148 and can be gripped together with it. When the desired height of the carriage 138 has been reached, the clamping lever 164 is released, so that the adjusting bolt 160 is pressed back into its rest position via the plate springs 162. The two balls 156 thus also return to their starting position, so that the sleeve 154 then clamps the housing 114.

FIGS. 21 to 28 show a further variant of the invention, in which the support plate 26 is fastened with the cover strip 30 to a swivel arm 166. The swivel arm 166 consists of a rectangular hollow profile body, the end of which points away from the support plate 26 is pivotably mounted on an axis 168 fastened to the side wall 10 of the work table 12. As FIG. 26 shows, the axis 168 has a cutout 170 into which a locking bolt 172 which is resiliently mounted in the direction of its axis engages. As a result, the maximum swivel angle for the swivel arm 166 is specified, which is indicated in FIG. 22. The dot-dash position of the swivel arm 166 corresponds to a vertical adjustment of the cover strip 30 by 75 mm.

The locking pin 172 can be brought out of engagement with the recess 170 by means of a handle 174 attached to it, so that the pivot arm 166 can then be pivoted away, for example when the knife shaft 34 has to be replaced.

To rotate the swivel arm 166, it is connected to an actuating lever 176, the angular position of which is adjustable. For this purpose, the end of the actuating bracket 176 located near the axis 168 is fixedly connected to a support plate 178 which is pressed by a lock nut 180 against a friction disk 182 which in turn rests on a driving disk 184 which is fixed to the axle via a pin 186 168 is connected. The lock nut 180 is tightened so tight that the friction is large enough to leave the operating lever 176 in any desired angular position in order to change the height setting of the support plate 26 and thus the cover strip 30. In the new angular position of the swivel arm 166, a helical spring 188, as shown in FIG. 26, presses a contact bolt 190 against a driver element 192. In particular when dressing serial parts or large workpieces, a vertical gap remains between the cover strip 30 and the cutter shaft 34, so that the workpiece can be pushed through. Then, as already explained above, the cover strip 30 is pressed downward, specifically against the force of the spring 188, which then pushes the swivel arm 166 back upwards into its set angular position.

In order to press the cover strip 30 with the required pressing force in the direction of the joining stop 36, a gas spring 194 is installed in the swivel arm 166 in this exemplary embodiment. The free end of the piston rod 196 of the gas spring 194 carries an axis 198 on which a deflecting roller 200 can be rotated on each side of the gas spring 194 is stored. In the area of the connection point of the support plate 26 to the swivel arm 166, one end 60 ′ of the cable pull 60 is clamped in this, which is indicated in FIGS. 21 and 23. FIG. 21 also shows that the cable pull 60 is guided via the deflecting roller 200 'to a deflecting roller 202 which is mounted within the swivel arm 166 and whose axis is perpendicular to the axis 198 of the two deflecting rollers 200. The cable pull 60 runs back over the deflection roller 202 to the second deflection roller 200 ″ and then back through a connecting channel 204 to a deflection roller 206 which is mounted on the support plate 26. The other end 60 ″ of the cable pull 60 is in one by means of a clamping screw 208 Stop element 210 clamped, which in turn is extensively connected to the cover strip 30 and serves as an end stop for the cover strip 30.

By the described guidance of the cable 60 in the manner of a pulley, it is achieved that with a maximum deflection of the piston rod 196 of the gas spring 194 by the stroke s of 150 mm, the cover strip 30 can be adjusted four times, the pressure force of the gas spring 194 a quarter of the pressing force of the cover strip 30 and thus the pressure shoe 38 is reduced.

The variant shown in FIGS. 21 to 28 with swivel arm 166 is also suitable for surface planing and thicknessing machines which are combined with a milling cutter and circular saw, since the planing protection device can be swiveled below the table level.

For the subsequent installation of the cover strip 30 according to the invention on previously conventional swivel arms of conventional machines, it is sufficient to attach an adapter piece to the end of the existing swivel arm, to which the support plate 26 for the cover strip 30 is screwed.

Finally, FIG. 29 indicates the possibility of generating the pressing force for the cover strip 30 by means of an electronically controlled stepper motor 212, which is connected to the cover strip 30 via a rack or the like, not shown.

The motor 212 moves the cover strip 30 to the joining stop 36 for joining a workpiece 48 and then returns about 1 mm. When touching the inlet beak 40 of the pressure shoe 38, the workpiece 48 to be joined triggers an opening movement of the cover strip 30 until the workpiece thickness shown in dashed lines is reached. In regular time units, e.g. B. every two seconds, this joining position is checked. This prevents a manual displacement of the joining stop 36 from causing an incorrect and dangerous position of the cover strip 30. When the workpiece 48 is joined, the movement of the cover strip 30 is recognized by the motor 212 and a pressing force of approximately 25 N is used. The force in setting the initial position may be less to allow faster initial setting.

For very wide workpieces 48, in which no opening adjustment is possible via the inlet beak 40, the cover strip 30 can be pre-positioned. This pre-positioning can be saved. In order to ensure a safe working environment, the cover strip 30 can be removed after a certain time, e.g. after 20 seconds without machining the workpiece, close fully. This pre-positioning can be resumed when a switch is actuated.

To carry out dressing work, the cover strip 30 is also moved in the direction of the joining stop 36 via the motor 212, in order then to move back by approximately 1 mm. Here too, at regular intervals, e.g. the dressing position is checked every two seconds to prevent manual displacement of the joining stop 36 from resulting in an incorrect and dangerous position of the cover strip 30.

The variant explained in FIG. 29 for setting the cover strip 30 by means of an electric motor 212, which also exerts the required pressing force, has various advantages. The width of the workpiece 48 is determined via the position of the cover strip 30 by monitoring the generated voltage and the current consumption on the electric motor. The cover strip 30 can be used according to the invention. Instead of a mechanical spring (mainspring or spiral spring) or a gas spring, each with a predetermined spring constant, a programmable spring is available which emits a reduced force in a specific position or with a specific force or when a workpiece 48 is introduced. There is thus an "intelligent" spring available that can "remember" a certain position and after a certain period of time without work covers the dangerous areas above the knife shaft 34. The work can be resumed quickly due to the saved position.

The motorized solution can be provided in an analogous manner for the vertical movement drive of the cover strip 30.

Claims (28)

1. A guard for planing machines for jointing and smoothing workpieces of wood, having a member for covering the cutter shaft (34) which is mounted so as to be vertically movable on one side of the work bench and comprises a cover strip (30) which is mounted on a support plate (26) so as to be horizontally displaceable against a pressing force acting in the direction of a jointing stop (36), characterized in that the support plate (26) is mounted on a lifting device (18) which is connected to a following device for automatically returning the cover strip (30) both from above and from below into an adjustable rest position above the cutter shaft (34).

2. A guard according to Claim 1, characterized in that the following device comprises a vertically adjustable gas spring (116) which is supported on a carrier (14) for mounting the lifting device (18).

3. A guard according to Claim 1 or 2, characterized in that four guide rollers (28), which are arranged opposite one another in pairs and between which the cover strip (30) is mounted so as to be displaceable in the direction of the longitudinal axis (32) thereof, are mounted on the support plate (26).

4. A guard according to one of the preceding Claims, characterized in that the lifting device (18) is connected to a weight-relieving means for the cover strip (30).

5. A guard according to Claim 4, characterized in that the weight-relieving means comprises a motive spring (92) with adjusting pre-stressing.

6. A guard according to Claim 4, characterized in that the weight-relieving means comprises a gas spring (150).

7. A guard according to Claim 4, characterized in that the weight-relieving means comprises an electronically controlled stepping motor.

8. A guard according to Claim 5, characterized in that the lifting device (18) comprises two vertical rods (20) which are mounted in ball- bearing bushes (24) mounted on the carrier (14) and are connected by way of a cable line (104) to the motive spring (92) secured to the carrier (14) to relieve the weight.

9. A guard according to Claim 6, characterized in that the lifting device (18) comprises a slide (138) which is mounted by way of guide rollers (142) on a guide rail (144) secured to the carrier (14), wherein the gas spring (150) for relieving the weight engages on the carrier (14) at one end and on the slide (138) at the other end.

10. A guard according to Claims 8 and 9, characterized in that a housing (114) of the vertically adjustable gas spring (116) is connected in an articulated manner at its upper end to a lifting lever (110) which is mounted pivotably on the carrier (14), the support plate (26) being supported on the free end of the said lifting lever (110).

11. A guard according to Claim 10, characterized in that a piston rod (120) of the gas spring (116) is articulated at its downwardly pointing end to a sliding plate (124) which is arranged in a guide rail (126) of the carrier (14) so as to be vertically displaceable and fixable.

12. A guard according to Claim 11, characterized in that a compression spring (134) acts upon the lower end of the sliding plate (124).

13. A guard according to Claim 11 or 12, characterized in that the piston rod (120) of the vertically adjustable gas spring (116) is supported with its downwardly facing end on the carrier (14), while the housing (114) of the gas spring (116) is displaceable relative to the slide (138) and is fixable thereon.

14. A guard according to Claim 4, characterized in that the lifting device (18) comprises a pivot arm (166).

15. A guard according to Claim 14, characterized in that the pivot arm (166) receives a gas spring (194) for generating the pressing force, which is provided at the free end of its piston rod (196) with at least one deflection roller (200) for a cable line (60) which is guided by way of further deflexion rollers (202, 206) in the manner of a block and tackle and is secured to the pivot arm (166) at one end and to the cover strip (30) at the other end.

16. A guard according to Claim 14 or 15, characterized in that the pivot arm (166) is connected displaceably to an actuating lever (176).

17. A guard according to Claim 16, characterized in that the following device comprises a helical spring (188) mounted in the pivot arm (166).

18. A guard according to one of the preceding Claims, characterized in that the free end of the cover strip (30) pointing towards the jointing stop (36) carries a pressure shoe (38) from which an inlet beak (40) projects, the inlet beak (40) being situated in a plane (12) - which extends parallel to the work bench (12) - and forming an acute angle (a) with the jointing stop (36).

19. A guard according to Claim 18, characterized in that the inlet beak (40) is pivotable in the pressure shoe (38) about a horizontal axis (44) situated transversely of the longitudinal axis (32) of the cover strip (30) into a position which is turned through 90 and in which it projects upwards from the work bench (12).

20. A guard according to Claim 18 or 19, characterized in that the inlet beak (40) consists of a material which is harder than the material of the pressure shoe (38).

21. A guard according to one of the preceding Claims, characterized in that the cover strip (30) is interrupted in the central region thereof by a hinge (80) by way of which the rear part (30") of the cover strip (30) pointing away from the jointing stop (36) can be swung downwards.

22. A guard according to Claim 21, characterized in that the hinge (80) has associated therewith a fixing means (82) for locking the rear part (30") of the cover strip (30) in a horizontal position in alignment with the front part (30').

23. A guard according to one of the preceding Claims, characterized in that a motive spring (52) is provided for generating the pressing force upon the cover strip (30).

24. A guard according to one of Claims 1 to 22, characterized in that a gas spring (194) is provided for generating the pressing force upon the cover strip (30).

25. A guard according to one of Claims 1 to 22, characterized in that an electronically controlled stepping motor (212) is provided for generating the pressing force upon the cover strip (30).

26. A guard according to Claim 23, characterized in that the motive spring (52) is mounted on the support plate (26) and is connected to the cover strip (30) by way of a cable line (60).

27. A guard according to Claim 26, characterized in that the cover strip (30) carries, in a displaceable manner in the direction of the longitudinal axis (32) thereof, a fixable stop member (64) on which the cable line (60) engages.

28. A guard according to Claim 27, characterized in that the stop member (64) comprises two clamping jaws (66) which engage around the cover strip (30) on the two longitudinal sides thereof and which rest on a common support pin (68) on which they are displaceable into a non-clamping position by means of a releasing lever (74) against the force of spring members (78).

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