EP2072199B1 - Hand-held circular saw - Google Patents

Description

The present invention relates to a circular saw, in particular an electric circular plunge saw, with a base part, a machine part comprising a driven saw blade, and an adjusting device by means of which the saw blade for adjusting a desired depth of cut relative to the base part adjusted, in particular pivoted, can be. The preamble of claim 1 is based on DE 3635159 ,

Circular saws with adjustable cutting depth sometimes offer the possibility of pre-scratching. For this purpose, the saw blade is adjusted to such a small depth of cut that the workpiece to be machined is scratched only superficially. The circular saw is moved with this preset scoring cutting depth according to the desired cutting line. In a further operation, the actual saw cut is done with deeply dipped saw blade along the pre-scored line. By pre-scoring a tearing or splintering of the workpiece surface can be avoided.

However, in practice, the problem often arises that the cutting line varies with respect to the workpiece surface with the depth of cut. This is due to the circular shape of the circular saw blade and has the consequence that the cutting lines during pre-scoring and the actual sawing, hereinafter referred to as pre-scoring cut line and saw cut line, slightly differ from each other. As a result, the saw cut is done outside the pre-scored area, so that the pre-scored line is largely ineffective. It can therefore come with conventional circular saws despite pre-scoring to a ripping of the workpiece surface.

This problem arises e.g. when the saw blade is not aligned exactly parallel to the working direction of the machine, e.g. due to a deliberately set free-cutting angle, ie a deliberate slight tilting of the cutting plane with respect to the working direction of the circular saw, whereby a jamming of the saw blade during sawing is counteracted. However, the said problem can also arise without intentional adjustment of a clearance angle, e.g. when the saw blade is not exactly parallel to the working direction of the machine due to manufacturing tolerances, as it is actually desired, or if the storage of the saw blade is associated with a relatively large game.

The object of the invention is to provide a portable circular saw, in which this problem does not occur.

The object is achieved by the features of claim 1.

According to the invention, the adjusting device displaces the saw blade when a predetermined cutting depth, in particular a scoring cutting depth, is exceeded, transversely to the working direction with respect to the base part.

By a transverse offset of the saw blade can be ensured that the cutting line at low depth of cut and the cutting line come at high depth of cut to cover and so in particular a pre-scored line unfolds its full effect.

Possible developments of the invention are specified in the dependent claims, the drawings and the description.

Preferably, the cutting plane defined by the saw blade is tilted by a free-cutting angle with respect to a working direction of the portable circular saw.

Furthermore, it is preferably provided that the adjusting device displaces the saw blade by a predetermined amount. This may, for example, be the amount which corresponds to the discrepancy between the scoring line and the saw cut line on the surface of the workpiece at a certain cutting depth which is particularly relevant for practice.

The predetermined amount of the transverse offset may in particular be about 1/10 mm to a few tenths of a millimeter. With such a transverse offset, the effect of a deliberately provided free-cutting angle or a principle undesirable inaccuracy or tolerance angle, which is about 0.1 ° to a few tenths of a degree, can be compensated in the manner according to the invention, wherein in this invention by the invention in both directions tilting or Deformations are compensated.

An expedient embodiment of the invention provides that the amount of the transverse offset is independent of the extent of exceeding the predetermined cutting depth. This results, for example, in a simple changeover between the two basic operating modes "pre-scoring" and "sawing".

In a further expedient embodiment of the invention, the amount of the transverse offset varies depending on the degree of exceeding the predetermined cutting depth. This way can be considered the circular shape of the saw blade an exact adjustment of the cutting line to the current cutting depth done.

Preferably, the amount of transverse offset is determined such that the line of intersection of the offset saw blade, i. the cut formed by the offset saw blade in the workpiece, at least substantially congruent with the cutting line of the unsplit saw blade, i. with the cut formed by the unsupported saw blade in the workpiece is. This ensures that the saw cut is made within the pre-scored area, thus avoiding tearing of the workpiece edges.

According to a preferred embodiment of the invention, the adjusting device comprises a positive control for the machine part, which converts the adjustment movement of the machine part in the transverse displacement movement of the machine part with respect to the base part. As a result, the cutting line displacement during the immersion of the saw blade in the workpiece is effectively automatically compensated, without the user has to pay attention to it.

A further advantageous embodiment of the invention provides that the machine part is articulated via a pivot bearing with transverse to the direction of rotation pivot axis on the base part, wherein the machine part in the pivot bearing has at least one of the amount of the transverse offset corresponding axial clearance. Swivel bearings of this type are often provided in circular saws with adjustable cutting depth, so that the targeted provision of an axial clearance in a particularly simple and cost-effective manner can allow a transverse offset.

Particularly preferably, the machine part is biased against the transverse displacement direction. This ensures that the saw blade at a Resetting the cutting depth from saw cut depth to scoring cut depth or to a home position returns to its original position.

The pivot bearing preferably has a bearing section which comprises a restoring device, in particular a spring, against the restoring force of which the transverse offset movement of the machine part takes place. Such a return device on the pivot bearing of the machine part allows a particularly simple embodiment of the bias.

According to a preferred embodiment of the invention, the pivot bearing on a bearing portion comprising a base part-side control surface and a machine part-side control surface, which cooperate in a pivoting of the machine part and force the transverse displacement movement of the machine part. The provision of control surfaces on a bearing portion of the pivot bearing is a particularly simple, cost-saving and robust way to control the transverse offset.

A further preferred embodiment of the invention is that the base part-side control surface is formed on a bearing block of the base part and the machine-part-side control surface on a bearing block of the machine part. Since bearing blocks are often present on circular saws of the type mentioned, they can be used advantageously for the provision of control surfaces.

According to one embodiment of the invention, the bearing block of the base part and / or the bearing block of the machine part is provided with a separate, rotatably mounted bearing disc on which the one control surface is formed. Such a separate bearing disc makes it possible to optimize the properties of one of the control surfaces by appropriate selection of materials, for example in terms of durability or frictional resistance. Furthermore, the control parameters, for example the maximum transverse offset, can be easily changed by replacing the bearing disk.

In a preferred embodiment of the invention, the control surfaces are designed such that essentially only one state with unadjusted saw blade or a state with offset by a single predetermined amount saw blade can be produced. This allows a simple changeover between the two basic operating modes "pre-scoring" and "sawing".

According to a further advantageous embodiment of the invention, the control surfaces are designed such that intermediate states can be produced between a state with an unadjusted saw blade and a state offset by a predetermined maximum amount saw blade in which the amount of transverse offset is less than the maximum transverse offset, wherein In particular, the amount of transverse offset increases steadily with increasing depth of cut. By suitably selected intermediate states, a fine-tuning of the transverse offset can take place as a function of the depth of cut.

According to an expedient embodiment of the invention, the one control surface on at least one projecting in the axial direction of the cam, which is in response to the relative position between the machine part and the base part with a recess formed in the other control surface in or out of engagement. The provision of a cam on the one control surface and a corresponding recess on the other Control surface simplifies the production of the control surfaces and thus reduces costs.

Advantageously, the cam engages the recess until it reaches the predetermined cutting depth and is disengaged when the predetermined cutting depth is exceeded with the recess. An annoying or unnecessary transverse offset before reaching the predetermined cutting depth is thereby avoided.

Fig. 1

eine schematische Draufsicht auf eine erfindungsgemäße Handkreissäge;

Fig. 2A

eine schematische Veranschaulichung von Vorritzund Sägeschnittlinie einer Handkreissäge gemäß dem Stand der Technik;

Fig. 2B

eine schematische Veranschaulichung von Vorritzund Sägeschnittlinie einer erfindungsgemäßen Handkreissäge;

Fig. 3A

eine Seitenansicht eines Lagerabschnitts einer erfindungsgemäßen Handkreissäge, wobei der Nocken mit der zugehörigen Ausnehmung in Eingriff steht; und

Fig. 3B

eine Seitenansicht eines Lagerabschnitts einer erfindungsgemäßen Handkreissäge, wobei der Nocken mit der zugehörigen Ausnehmung außer Eingriff steht.

The invention will now be described by way of example with reference to the drawings. In this show:

Fig. 1

a schematic plan view of a portable circular saw according to the invention;

Fig. 2A

a schematic illustration of Vorritzund saw cut line of a portable circular saw according to the prior art;

Fig. 2B

a schematic illustration of Vorritzund saw cut line of a portable circular saw according to the invention;

Fig. 3A

a side view of a bearing portion of a circular saw according to the invention, wherein the cam is in engagement with the associated recess; and

Fig. 3B

a side view of a bearing portion of a portable circular saw according to the invention, wherein the cam with the associated recess is disengaged.

In the Fig. 1 A circular saw, which is schematically illustrated in plan view, is an electric plunge-type circular saw which comprises a base part 13, a machine part 15 and an adjusting device 19. The machine part 15 comprises an electric motor (not shown) and a saw blade 17 driven by it. The machine part 15 is articulated to the base part 13 via a pivot bearing 21, wherein the pivot axis 41 (FIG. FIGS. 3A and 3B ) is aligned transversely to the indicated by an arrow working direction A of the circular saw. The working direction A is predetermined, for example, by a stop device provided on the base part 13, which interacts with a workpiece edge or a guide aid, or by a target device, by means of which a user aligns the portable circular saw with a marking (tear) applied to the workpiece. By pivoting the machine part 15 including the associated with this saw blade 17, the saw blade 17 from a basic position in which it does not touch the surface of the workpiece to be machined, immersed with variable depth in the workpiece and guided according to the broken line through the workpiece become. To counteract jamming of the saw blade 17 during sawing, the cutting plane defined by the saw blade 17 is tilted with respect to the working direction A by a so-called free-cutting angle, which is why the axis of rotation of the saw blade 17 is not exactly perpendicular to the working direction A. The tilt around the clearance angle is in the simplified representation of Fig. 1 Not shown. In FIGS. 2A and 2B the clearance angle is exaggerated for clarity. In the FIGS. 3A and 3B shown pivot axis 41 extends parallel to the axis of rotation of the saw blade 17 and thus also not exactly perpendicular to the working direction A. Alternatively, the pivot axis 41 can run exactly perpendicular to the working direction A, so that the clearance angle of the saw blade 17 to others Way is realized. For example, a motor unit arranged in the machine part 15 can be correspondingly rotated for the saw blade 17 in order to ensure the free-cutting position of the saw blade 17.

The circular saw is equipped with a scoring function, that is, the immersion depth can be limited to a value corresponding to a superficial scoring of the workpiece by the saw blade 17. After deactivating the scribing function, for example by releasing the associated cutting depth limiting device, the saw blade 17 can be dipped deeper into the workpiece so as to perform a saw cut.

In a hand-held circular saw according to the prior art, this results in the Fig. 2A schematically illustrated situation. During scoring, only a small part of the saw blade dips into the workpiece, so that the small area of the workpiece surface, indicated by a solid line, is processed by the saw blade. Turning to the side of the workpiece to be used later results in the cutting line S. If the saw blade is now immersed deeper into the workpiece, the extended area shown in dashed lines is processed by the saw blade and the cutting line S 'results. As can be seen, the cutting lines S and S 'are offset relative to each other due to the clearance angle, that is, the cutting line S' of the dipped saw blade is displaced from the cutting line S of the scoring saw blade toward the workpiece side to be used. Thus, the saw cut is not completely within the pre-scored area, so scoring is largely ineffective. The same problem arises when, for example, due to manufacturing tolerances or a relatively large bearing clearance a - actually desired - exact alignment of the saw blade parallel to the working direction of the machine is not given.

However, according to Fig. 2B the saw blade offset transversely to the working direction A with respect to the base part of the circular saw when the scoring cut depth is exceeded, it can be achieved that the cutting lines S and S 'are congruent and the effect of scoring fully comes into play. The type of offset can be such that there is only one set, corresponding to the pre-scoring threshold depth and a fixed amount of transverse offset, so that the amount of the transverse offset of the extent of exceeding the scoring cut depth is independent. However, it can also be provided to adapt the transverse offset in one or more intermediate steps or in a continuous manner to the cutting line which shifts according to the depth of cut.

Conveniently, the transverse offset occurs simultaneously with the dipping motion without requiring user action. Such a forced control for the machine part 15, which converts the pivoting movement into a suitable transverse offset movement with respect to the base part 13, can be realized in a simple manner by providing a movement latitude transversely to the working direction A in the already existing pivot bearing 21 of the portable circular saw. For this purpose, the machine part 15 in the pivot bearing 21 a deliberately selected axial clearance, which here corresponds to the maximum amount of the transverse offset. As in Fig. 1 can be seen, the pivot bearing 21 of the circular saw on a bearing portion 23 and a bearing portion 25. Both bearing sections 23, 25 are each formed by a bearing block 31 of the base part 13 and a bearing block 33 of the machine part 15, which together store a pivot pin, not shown. At the storage section 23 is a return device 24th between the bearing block 31 of the base part 13 and the bearing block 33 of the machine part 15, which biases the machine part 15 against the transverse displacement direction in the direction of the bearing portion 25. The return device 24 is shown in the drawing as a helical spring. Alternatively, it may also be a diaphragm spring or the like. At the bearing portion 25 of the bearing block 33 of the machine part 15 is rotatably connected to a separate bearing plate 35, which may be made of a suitable material.

The FIGS. 3A and 3B represent the bearing portion 25 in more detail. On the bearing block 31 of the base member 13 and the bearing plate 35 is a base part-side control surface 27 and a machine part-side control surface 29 is formed, which slide against each other and thereby cooperate in a pivoting of the machine part 15. It can be seen that the control surfaces 27, 29 are not flat, but that in the base part-side control surface 27, a cam 37 and in the machine part-side control surface 29, a recess 39 is formed. According to the pivot position of the machine part 15 of the cam 37 is in engagement with the recess 39 or disengaged. When the cam 37 according to Fig. 3A is engaged with the recess 39, the machine part 15 is in the unset position. When the cam 37 according to Fig. 3B moved out of engagement with the recess 39, the machine part 15 is pressed against the spring bias in the direction of the bearing portion 23, resulting in a transverse offset of the machine part 15 results in Fig. 3B denoted by D.

The cam 37 and the recess 39 are matched to one another in such a way that, starting from the basic position of the machine part 15, they engage until reaching the predetermined cutting depth and only disengage when the predetermined cutting depth is exceeded. In the FIGS. 3A and 3B shown control surfaces 27, 29 provide essentially only two states, which correspond to no transverse offset and a maximum transverse offset D. However, the cam 37 and the recess 39 have a smooth running profile to allow an optimized sliding movement in the transition from the unset to the staggered state. Alternatively, it is possible to give the control surfaces a more complex profile, so as to provide, for example, intermediate states or even to create a continuous transverse offset as a function of the depth of cut.

When using the portable circular saw according to the invention, a compensating transverse offset of the machine part 15 is effected during the dipping movement, so that the saw cut is oriented exactly on the pre-scored line and tearing of the workpiece edges is prevented. The user does not have to be careful to consider the exact transverse offset, for example, by adjusting or resetting it, since the compensation takes place automatically in the course of the pivoting movement. This advantageous function can be provided in a simple and cost-effective manner by providing the existing pivoting device of a portable circular saw with a controllable axial play.

LIST OF REFERENCE NUMBERS

13

base

15

machinery

17

sawblade

19

adjustment

21

pivot bearing

23

bearing section

24

Reset device

25

bearing section

27

base-part-side control surface

29

Machine part side control surface

31

Bearing block of the base part

33

Bearing block of the machine part

35

bearing disk

37

cam

39

recess

41

swivel axis

A

working direction

S

Cutting line of the saw blade in scoring position

S '

Cut line of saw blade in saw position

D

transverse offset

Claims (15)

1. A hand-held circular saw, in particular an electrical plunge circular saw, comprising
   a base part (13);
   a machine part (15) which includes a driven saw blade (17); and
   an adjustment apparatus (19) by means of which the saw blade (17) can be adjusted, in particular pivoted, for setting a desired cutting depth relative to the base part (13),
   characterised in that
   the adjustment apparatus (19) displaces the saw blade (17) transversely to the direction of work (A) with respect to the base part (13) on an exceeding of a predefined cutting depth, in particular a prescoring cutting depth.
2. A hand-held circular saw in accordance with claim 1,
   characterised in that
   the adjustment apparatus (19) displaces the saw blade (17) by a predefined amount.
3. A hand-held circular saw in accordance with claim 2,
   characterised in that
   the amount of the transverse displacement is independent of the amount of the exceeding of the predefined cutting depth.
4. A hand-held circular saw in accordance with claim 2,
   characterised in that
   the amount of the transverse displacement is varied in dependence on the amount of the exceeding of the predefined cutting depth.
5. A hand-held circular saw in accordance with any one of claims 2 to 4,
   characterised in that
   the amount of the transverse displacement is determined such that the cutting line (S') of the displaced saw blade (17) is at least substantially congruent with the cutting line (S) of the non-displaced saw blade (17).
6. A hand-held circular saw in accordance with any one of the preceding claims,
   characterised in that
   the adjustment apparatus (19) includes a compulsory control for the machine part (15) which converts the adjustment movement of the machine part (15) into the transverse displacement movement of the machine part (15) with respect to the base part (13).
7. A hand-held circular saw in accordance with any one of the preceding claims,
   characterised in that
   the machine part (15) is pivotally connected via a pivot bearing (21) having a pivot axis (41) extending transversely with respect to the direction of work (A) to the base part (13), with the machine part (15) having at least axial play corresponding to the amount of the transverse displacement in the pivot bearing (21).
8. A hand-held circular saw in accordance with claim 7,
   characterised in that
   the machine part (15) is preloaded against the transverse displacement direction, with the pivot bearing (21) preferably having a bearing section (23) which includes a restoring device (24), in particular a spring, against whose restoring force the transverse displacement movement of the machine part (15) takes place.
9. A hand-held circular saw in accordance with one of the claims 7 to 8,
   characterised in that
   the pivot bearing (21) has a bearing section (25) which includes a control surface (27) at the base part side and a control surface (29) at the machine part side which cooperate on a pivoting of the machine part (15) and enforce the transverse displacement movement of the machine part (15).
10. A hand-held circular saw in accordance with claim 9,
    characterised in that
    the control surface (27) at the base part side is formed at a bearing block (31) of the base part (13) and the control surface (29) at the machine part side is formed at a bearing block (33) of the machine part (15).
11. A hand-held circular saw in accordance with claim 10,
    characterised in that
    the bearing block (31) of the base part (13) and/or the bearing block (33) of the machine part (15) is provided with a separate bearing disk (35) which is arranged rotationally fixedly and at which a control surface (29) is formed.
12. A hand-held circular saw in accordance with any one of the claims 9 to 11,
    characterised in that
    the control surfaces (27, 29) are formed such that substantially only one state can be established with a non-displaced saw blade (17) or a state with a saw blade (17) displaced by a single predefined amount.
13. A hand-held circular saw in accordance with any one of the claims 9 to 11,
    characterised in that
    the control surfaces (27, 29) are formed such that intermediate states can also be established between a state with a non-displaced saw blade (17) and a state with a saw blade (17) displaced by a predefined maximum amount, in which intermediate states the amount of the transverse displacement is smaller than the maximum transverse displacement, with in particular the amount of the transverse displacement constantly increasing as the cutting depth increases.
14. A hand-held circular saw in accordance with any one of the claims 9 to 13,
    characterised in that
    the one control surface (27) has at least one cam (37) which projects in the axial direction and which is in or out of engagement with a cut-out (39) formed in the other control surface (29) in dependence on the relative position between the machine part (15) and the base part (13), with preferably the cam (37) being in engagement with the cut-out (39) up to the reaching of the predefined cutting depth and being out of engagement with the cut-out (39) on an exceeding of the predefined cutting depth.
15. A hand-held circular saw in accordance with any one of the preceding claims,
    characterised in that
    the cutting plane defined by the saw blade (17) is tilted by a free-cutting angle with respect to a direction of work (A) of the hand-held circular saw.

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