JP2000084730A - Hand-held machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hand-held machine tool superior in toughness and abrasion resistance. SOLUTION: In a hand-held machine tool, particularly a precision cut saw 9, comprising a tool 12 reciprocatably driven through an eccentric 20 and a connecting rod 22 by a shaft to be driven 17, and preferably a counter weight 30 driven through the eccentric 20 and another connecting rod 29, the eccentric 20 is formed as a disc plate eccentrically arranged on the shaft to be driven 17 in a state that they can not be relatively rotated, its outer peripheral surface 204 is rotatably engaged with particularly a circular recessed part 290 of the connecting rod 29, at least one rotatable rolling element 205 is supported between the outer peripheral surface 204 and the recessed part 290, and this rolling element 250 reduces the resistance when the eccentric rotor 20 rotates to the connecting rod 29.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hand-held machine tool, particularly a precision cutting saw, which is reciprocally driven by a driven shaft through an eccentric and a connecting rod, and preferably an eccentric. And a counterweight driven via another connecting rod.

[0002]

2. Description of the Related Art In a hand-held machine tool described in German Patent No. 19625081, a counterweight for compensating vibration of a single saw blade reciprocally driven is provided with a disk-shaped eccentric. It is known to reciprocate in the opposite direction to the saw blade movement by a connecting rod surrounding the. In this case, the eccentric is formed as a plain bearing with an expensive material composition in the area of contact with the connecting rod, on the one hand relatively good sliding properties and on the other hand a high impact load at the point of reversal of reciprocation. It also has sufficient wear resistance.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned disadvantages of the prior art.

[0004]

In order to solve the above-mentioned problems, according to the present invention, an eccentric is formed as a disk which is eccentrically arranged on a driven shaft so as to be relatively non-rotatable, and has an outer peripheral surface thereof. A rotatable engagement of another connecting rod, in particular a circular recess, supports at least one rotatable rolling element between the outer peripheral surface and the recess, the rolling element comprising an eccentric connecting rod. When rotating with respect to, it works to reduce friction.

[0005]

According to the hand-held machine tool of the present invention having the structure described in the first aspect, the eccentric and the connecting rod can be connected to each other in a high impact load range by arranging at least one rolling element. There is the advantage that there is a very shock-resistant rolling contact between them and, in other areas, an optimal lubricating sliding contact, as a result of which the hand-held machine tool has a particularly long service life.

In accordance with an advantageous embodiment of the invention, the vibrations caused by the saw blade are reduced by a counterweight which is specially adjusted according to the mass to be moved, ie the saw blade, the connecting rod, the drive finger and the like. . The counterweight is slidably mounted in the machine casing in the longitudinal direction and is driven by a connecting rod into a reciprocating sliding movement. This connecting rod rests on an eccentric which is connected to the driven shaft of the transmission in such a way that it cannot rotate relative to it.

The eccentric has at least one rolling element pocket formed as a recess on the outer peripheral surface thereof, and the rolling element is rotatably supported in the rolling element pocket. The impact strength of the rotary bearing between the connecting rod and the eccentric is improved at a definable point on the outer peripheral surface of the shaft, without impairing the sliding characteristics.

[0008] By arranging at least one grease pocket on the outer peripheral surface as a concave depression, the sliding properties between the connecting rod and the eccentric are improved.

An eccentric is spaced radially from the outer peripheral surface and supports, in particular, two cavities serving as lubricant containers, which cavities communicate with the rolling element pockets and are eccentric. The friction between the rolling elements and the rolling element pockets is improved by being arranged symmetrically with respect to the transverse mid-axis of the vessel.

[0010] The two grease pockets communicating with the lubricant container are arranged on the outer peripheral surface symmetrically with respect to the transverse mid-axis of the eccentric, so that there is a gap between the eccentric and the connecting rod. The sliding characteristics are further improved.

Due to the fact that the rolling elements are preferably formed as needle rollers having a length of 5 to 8 mm, in particular 4.5 mm and a diameter of 2 to 5 mm, in particular 3 mm, the impact strength is marked at an eccentric outer diameter of 24 mm. Significant improvements are achievable.

The eccentric supports a sliding bearing material having a copper component and a graphite component on its outer peripheral surface,
The sliding friction between the connecting rod and the eccentric is significantly improved.

The eccentric supports one needle-shaped rolling element in each of two rolling element pockets on its outer peripheral surface, and these two rolling element pockets are formed in eccentric holes through which the driven shaft passes. By being arranged substantially symmetrically with respect to the eccentric, in particular symmetrically about the transverse mid-axis of the eccentric, the impact strength between the connecting rod and the eccentric is optimally improved.

A particularly advantageous combination of slides between the connecting rod and the eccentric is provided by the fact that the two rolling element pockets and the two grease pockets are respectively arranged on the outer peripheral surface of the eccentric at an offset of 45 °. -A rolling bearing is formed.

According to an advantageous embodiment of the invention, a lubricant container is provided on the outer peripheral surface and at the bottom of the eccentric for temperature reduction. The resulting lubricant film is improved,
Grease is supplied from these pockets.

According to an advantageous embodiment of the invention, the connecting rod is axially held by an annular shoulder and a disk provided on the eccentric. The disc itself is in contact with the disc-shaped crank. By doing so, the inclination of the connecting rod during driving and the outflow of lubricant from the lubricant container are prevented.

According to an advantageous embodiment of the invention, the counterweight has a protruding pin which is slidably received in an eye formed in the connecting rod. The eye has a recess that projects toward the counterweight. Due to this retraction, the guide length or engagement length between the eye and the pin of the counterweight is increased, the point of application of the force becomes closer to the counterweight, and the generated moment is reduced.

According to an advantageous embodiment of the invention, the guidance of the counterweight takes place via a fixed spring arranged in the machine housing. Each of these fixed springs grips the upper and lower sides over the counterweight by two spring leg sides. At the same time, these fixed springs also guide the counterweight at its side edges.

The linear movement of the counterweight is ensured by fixing the counterweight transversely to the sawing direction. The fixed spring is preferably inserted into the casing shell of the machine casing and is retained in the casing via hooks. These fixed springs ensure tolerance compensation between the components and thus play-free travel of the counterweight.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings.

The electric hand-held machine tool shown in longitudinal section in FIG. 1 and in cross section in FIG. 2 comprises a machine casing 10 and an electric drive 11 housed therein, and a replaceable saw blade 12. And The saw blade 12 can be driven by the electric driving device 11 into a periodic reciprocating sawing motion, and the saw blade 12 performs a predetermined sawing stroke. The electric drive device 11 has an electric motor 13 and a motor shaft 14. A fan wheel 15 is provided on the motor shaft 14.
Are seated so that they cannot rotate relative to each other. Further electric drive 1
1 has a miter gear 16 whose driven shaft 17 is adjusted at right angles to the motor shaft 14. The motor shaft 14 supports a spur gear 18 at the end. Spur gear 1
8 meshes with a crown gear 19 connected to the driven shaft 17. This allows a large tolerance for the axial movement of the motor shaft 14 and consequently reduces the manufacturing costs of the gearing.

An eccentric 20, a disc-shaped crank 21, and a connecting rod 22 are arranged on the driven shaft 17 so as to be relatively unrotatable in the axial direction. Connecting rod 22 is crank 21
A drive finger 23 for the saw blade 12 is movably received in the front end region of the connecting rod 22 in the axial direction. A bearing pin 24 extending parallel to the driven shaft 17 is fixed in the crank 21 to pivotally connect the connecting rod 22. The bearing pin 24 is the crank 21
At right angles. The connecting rod 22 is a bearing bush 2
5 is mounted on the bearing pin 24 and is prevented from dropping off in the axial direction by a tension ring 26 inserted into the shaft cutout. In this case, the tensioning ring 26 can alternatively be omitted. A rolling element 27 is inserted between the bearing pin 24 and the bearing bush 25 (needle bearing). Here, a plain bearing can be used instead of a roller bearing.

The connecting rod 22 has a machine housing 10 on both sides in its front region receiving the drive finger 23.
As a result of being guided in the two guide lamellas 28 (FIG. 2), which are fixed to the drive finger 23, the drive finger 23 carries out an exactly linear movement and the connecting rod 22 cannot be displaced upward.

The eccentric 20 shown enlarged in FIGS. 4 and 5 has a connecting rod recess 2 of a connecting rod 29 on its outer peripheral surface 204.
90, the counterweight 30 is driven to reciprocate. The connecting rod 29 rotates along the upper annular shoulder 201 of the eccentric 20 and the flat disk 31 arranged between the eccentric 20 and the counterweight 30. As can be seen in FIG. 4, in the lower side of the eccentric 20 facing the disk 31, two cavities are provided mirror-symmetrically with respect to the transverse mid-axis 211, and the lubricant container Work as 202. Since each of these lubricant containers 202 is connected to the rolling element pocket 206 through one lubricant passage 210, when the eccentric 20 rotates around the center of the hole 217 through which the driven shaft 17 passes, the lubricant container 202 is lubricated. The agent is pressed against the rolling elements 205 radially outward by centrifugal force. The resulting lubricating film forms the rolling element 205 and the rolling element pocket 2
06 and the friction between the outer peripheral surface 204 of the eccentric 20 and the edge of the recess 290 of the connecting rod 29 are reduced. Excess lubricant accumulates in the grease pockets 207 arranged on the outer peripheral surface 204 of the eccentric 20 symmetrically with respect to the rolling elements 205, that is, shifted by 45 °, respectively, like the rolling elements 205. By doing so, the lubricant is more uniformly distributed between the outer peripheral surface 204 and the edge of the concave portion 290 of the connecting rod 29. From FIG. 4, the outer peripheral surface 204 of the eccentric 20
It can be seen that a portion of the outer surface 204 functions as a sliding bearing, and another portion of the outer peripheral surface 204 which receives an impact load functions as a roller bearing. Thus, the outer peripheral surface 204 of the eccentric 20 formed in part as a needle cage is connected to the connecting rod 29.
Together with the plain bearings form a combination with the bearings. In this case, the shock absorbing performance and the lubricating performance are attained to the highest values, and are achieved exactly where they are needed. That is, the impact absorption by the rolling elements 205 is achieved at the reversal point of the counterweight 30, and the best lubrication is achieved in a range where the surface compression is small and the peripheral speed is high.

A proven embodiment of the eccentric 20 has an outer diameter of 2
In the case of 4 mm, a rolling element having a diameter of 3 mm and a length of 4.5 mm is supported in the range of the outer peripheral surface 204. In this case, the lubricant passage 210 between the lubricant container 202 and the rolling element pocket 206 has a diameter of about 2.5 mm.

The arrangement of the annular shoulder 201 and the disk 31 prevents the lubricant from flowing out of the lubricant container 202 and prevents the connecting rod 29 from inclining during driving. Since the blind hole 203 in the lower side of the eccentric 20 and the journal 301 provided on the crank 21 that intrudes into the blind hole 203 assure the correct mounting of the eccentric 20, the counterweight 3
0 operates on the saw blade 12 at exactly the opposite timing.

The connecting rod 29 shown in FIG. 6 and FIG.
Is the counterweight 3 in the eye 290 in the front range.
The pin 302 (FIGS. 1 and 3) projecting from 0 is slidably received. The pin 302 may be formed integrally with the counterweight 30 or may be pressed into the counterweight 30. As can be seen in FIG. 7, the eye 291 has a recess 292 that projects toward the counterweight 30. By doing so, the pin 3 of the eye 291 and the counter weight 30
02 and the guide length or engagement length are larger. At the same time, the moment of action is reduced because the point of action is placed closer to the counterweight 30.

The counterweight 30 is supported in the machine casing 10 so as to be movable in the sawing direction in the axial direction. As can be seen from the perspective view of FIG. 3, when the x coordinate coincides with the sawing direction, the support of the counterweight 30 is performed in both the z coordinate and the y coordinate. In this case, the support is 4
This is performed by the fixed springs 32. These fixed springs 32 are pressed into the casing shell 101, and the hooks 3
It is held in the machine casing 10 via 21.
The position of the fixed spring 32 is precisely limited in the y direction by the abutment surface formed in the machine casing 10. Each of the fixed springs 32 has its upper and lower sides straddling the counterweight 30 by two spring leg sides 322, and abuts against the counterweight 30 by a preload. These fixed springs 32 ensure both tolerance compensation between the components and play-free travel of the counterweight 30. The counterweight 30 surrounds the disc-shaped crank 21 by an elliptical recess 57.

In order to tighten the saw blade 12 exchangeably,
A tensioning device 33 is formed in the machine casing 10.

As is clear from FIG. 2, the driving finger 23 for driving the saw blade 12 is guided by a hole 221 in the connecting rod 22 and an elongated hole in the fixing plate 34. In this case, the periodic reciprocation of the driving finger 23 is not hindered by the fixing plate 34 since the slot has a length exceeding the sawing stroke. In this case, the long hole is surrounded by a brim bent from the fixing plate 34, and a felt packing 41 impregnated with silicone is placed thereon (FIGS. 1 and 2). This slot is sealed by a circular cover plate 42. The cover plate 42 surrounds the drive finger 23 and moves with it linearly.
The cover plate 42 then slides over the felt packing 41, thereby sealing the machine outward. The silicone impregnation achieves the exact thickness of the felt packing 41 and thereby the stress-free arrangement of the connecting rod 22.

In a non-illustrated embodiment of a hand-held machine tool, instead of one needle-like rolling element 205 in each case in the rolling element pocket of the eccentric, two diameters 3 each are used.
mm sphere is inserted.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a hand-held machine tool.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a perspective view of a half shell of a casing.

FIG. 4 is a bottom view of the eccentric provided on the machine shown in FIG. 1 as viewed in the direction of arrow IV in FIG. 5;

FIG. 5 is a sectional view taken along the line VV of FIG. 4;

6 shows the connecting rod of the machine shown in FIG. 1 in the direction of arrow VI in FIG. 7;
FIG.

FIG. 7 is a longitudinal sectional view of the connecting rod shown in FIG. 6;

[Explanation of symbols]

9 Precision cutting saw, 10 Machine casing, 11
Electric drive, 12 saw blades, 13 electric motor,
Reference Signs List 14 motor shaft, 15 fan wheel, 16 miter gear, 17 driven shaft, 18 spur gear, 19 crown gear, 20 eccentric, 21 crank, 22 connecting rod, 23 drive finger, 24 bearing pin, 2
5 bearing bush, 26 tension ring, 27 rolling element, 28 guide thin plate, 29 connecting rod, 30 counter weight, 31 disk, 32 fixed spring, 33
Tightening device, 34 fixing plate, 41 felt packing, 42 cover plate, 101 casing shell, 202 lubricant container, 203 blind hole, 20
4 outer peripheral surface, 205 rolling element, 206 rolling element pocket, 207 grease pocket, 210 lubricant passage, 211 transverse mid-axis, 221 hole, 290
Recess, 292 retract, 301 journal,
321 hook, 322 spring leg side

Continued on the front page (72) Inventor Eduard Ganzel Germany Dettenhausen Wersenstrasse 30 (72) Inventor Alfred Flech Germany Rheinfelden-E Hitterdingen Geranienstrasse 21 (72) Invention Uwe Engelfleet Germany Ostfildern Boppserweg 31

Claims (9)

[Claims] 1. A hand-held machine tool, in particular a precision saw (9), comprising an eccentric (2) by a driven shaft (17).
0) and a tool (12) reciprocally driven via a connecting rod (22), and a counterweight (3) preferably driven via an eccentric (20) and another connecting rod (29).
0), the eccentric (2)
0) is formed as a circular plate arranged eccentrically relative to the driven shaft (17) so as not to rotate relative to the driven shaft (17), and its outer peripheral surface (20) is formed.
4) a particularly circular recess (290) of another connecting rod (29)
And at least one rotatable rolling element (205) is supported between the outer peripheral surface (204) and the recess (290), the rolling element (205) being an eccentric. A hand-held machine tool characterized in that (20) acts to reduce friction when rotating with respect to the connecting rod (29). 2. The eccentric (20) has an outer peripheral surface (204).
2. The rolling element according to claim 1, comprising at least one rolling element pocket formed as a recess on the rolling element, wherein the rolling element is rotatably mounted in the rolling element pocket. Hand-held machine tool. 3. Hand-held machine tool according to claim 1, wherein at least one grease pocket (207) is arranged on the outer peripheral surface (204) as a concave depression. 4. An eccentric (20) radially spaced from the outer peripheral surface (204) supports, in particular, two cavities serving as a lubricant container (202), and these cavities. 4. The hand-held machine tool according to claim 2, wherein the at least one is in communication with the rolling element pocket (206) and is symmetrically arranged with respect to the transverse mid-axis (211) of the eccentric (20). 5. A lubricant container (202) in communication with a lubricant container (202).
Grease pockets (207) are symmetrical with respect to the transverse mid-axis (211) of the eccentric (20).
4) The hand-held machine tool according to claim 4, wherein the machine tool is disposed as a recess. 6. The rolling element (205) preferably has a length of 5 mm.
2. The needle roller according to claim 1, which is formed as a needle roller of ８8 mm, in particular 4.5 mm and a diameter of 2-5 mm, especially 3 mm.
6. The hand-held machine tool according to any one of items 1 to 5. 7. The eccentric (20) has an outer peripheral surface (204).
7. The hand-held machine tool according to claim 1, further comprising a sliding bearing material having a copper component and a graphite component thereon. 8. The eccentric (20) has an outer peripheral surface (204).
One needle-shaped rolling element (205) is supported in each of the two rolling element pockets (206), and these two rolling element pockets (206) are supported by the driven shaft (17).
2. The hand-held machine tool according to claim 1, wherein the machine tool is arranged substantially symmetrically with respect to the eccentric hole (217) through which the eccentric passes, particularly with respect to the transverse middle axis (211) of the eccentric (20). . 9. The two rolling element pockets (206) and the two grease pockets (207) are arranged on the outer peripheral surface (204) of the eccentric (20), respectively, offset by 45 ° from each other. Hand-held machine tool.