FI94500B - Hand grinding machine - Google Patents

Abstract

Hand grinding machine 10 which is designed particularly for surface grinding of large level surfaces such as walls and roofs. The grinding machine comprises a motor 14 and a surface-grinding member 18 rotated by the motor. The surface-grinding member 18 is coupled to the motor by a two-part shaft 16, the first part of which is in the form of an extension shaft 20 and the second part of a fixed shaft 24. The shafts are joined at an angle greater than 90O. The surface-grinding member 18 is coupled to the fixed shaft 24 by a pivot 28 which allows the member to rotate. The pivot 28 allows the grinding member 18 to turn relative to the fixed shaft 24. <IMAGE>

Description

94500

HANDSLIPMASKIN HAND GRINDER

The present invention relates to a hand grinder for planar grinding of large planar surfaces, such as walls and ceilings, comprising a power machine such as a drill or a pneumatic machine and a 5-axis rotary wheel of a power machine connected by a joint such as a cross or ball joint switch to the arm connecting the surface grinding wheel to the power machine. The invention relates in particular to a hand grinder comprising a power machine, such as a drilling machine or a pneumatic machine, and a planar grinding member, such as a grinding wheel, rotated by the shaft of the power machine.

When painting or wallpapering walls and ceilings, the substrate must be clean and smooth. Old paint, wallpaper or other detachable surfaces must be removed, whether the wall or ceiling is made of concrete elements, building boards or even metal boards. The same applies, of course, to the exterior of houses or, for example, to the corresponding surfaces of ships. In addition, for example, the element walls may have a large number of joints, surface-20 cracks or other irregularities that must be smoothed before cladding or painting. The cleaning and leveling steps are heavy and still largely manual. A hand sander is used to some extent both in the rough cleaning, in the removal of the old surface layer, in the actual leveling of the substrate and in the final smoothing of the leveling compound. Smooth straight surfaces are sanded with surface grinders. Surface grinders are both electric and pneumatic. Most commonly, surface grinders are used for finishing grinding. However, surface grinding can also be used as an effective removal method.

For mechanical grinding, the surface grinder can be connected, for example, to a drilling machine or a pneumatic machine as an accessory. In this case, the grinding wheel is attached directly to the motor shaft - 2 94500 le. In this case, the motor must be kept exactly vertical to the ground to be sanded during grinding. The problem with using a grinding wheel is that the disc quite easily makes deep marks on the substrate to be cleaned if the disc 5 does not rest on the substrate to be sanded evenly over its entire surface.

Such work is heavy, because e.g. when sanding a wall, the machine must be moved by hand at a constant precise angle over the entire area to be sanded, e.g. from the floor boundary to the roof boundary. When sanding the top of the wall or the ceiling, a ladder or the like is needed so that the sander can usually get close to the sanding object and especially so that the machine can be kept in the correct position. The grinder has to be supported in the worst possible positions, so of course the grinding mark suffers and the work takes a lot of time.

Flexible grinding wheels and articulated grinding wheels have been developed for drilling machines. These make it somewhat easier to grind flat surfaces because the grinding wheel 20 adheres over the entire surface of the substrate to be sanded. However, the sanding machine still has to be supported against the substrate at the point to be sanded, i.e. the machine has to be supported by hand close to the floor or ceiling boundary, e.g. when sanding a wall. Even when working with such a machine, it is necessary to bend over in poor working positions and a ladder, etc. is required. Therefore, the use of grinding machines is often abandoned and sanding is done completely by hand, e.g. with sandpaper attached to a wooden block at the end of the shaft.

30

The object of the present invention is to provide a better hand grinder than previously known, in which the above-mentioned disadvantages are minimized.

. In order to achieve the objects of the invention, a hand grinder according to the invention 3 94500 is characterized by what is stated in the characterizing part of the first claim.

The hand grinder according to the invention has a planar grinding member, 5 a grinding wheel with an abrasive surface, connected to the power machine along the arm. The stem consists of the first so-called extension arm and another shorter so-called the mounting-arm. The extension arm is attached to the power unit at one end so that the power unit rotates the arm.

At one end, the extension arm is connected to the mounting arm via a transmission joint so that the angle between the arms is> 90 °, preferably 110 to 130 °, most preferably about 120 °, depending on the desired working position and the substrate to be sanded. In the grinder, a drilling machine, a pneumatic machine or another hand-held machine providing rotating movement can be used as a power machine, i.e. a rotating machine. A drilling machine that provides a rotational speed of <1000 rpm in the grinding wheel, preferably 300 to 700 rpm, is suitable for most grinding applications. Too high a rotational speed of 20 can cause too much dust.

The transmission joint between the extension and the mounting arm transmits the rotational movement from the extension arm to the mounting arm. In general, the rotational speed on these two arms is the same.

25 However, if desired, the transmission can be made with a transmission member, which changes the rotational speed, for example, slower in the mounting arm.

The planar grinding member, the planar grinding wheel, is connected via a joint 30 to the fixing arm so that the rotational movement of the arm is transmitted to the planar grinding member and so that the grinding member is movable in at least one plane with respect to the mounting arm. The abrasive member, the surface plane of which in the rest position is at an angle of 90 ° to the longitudinal direction of the mounting arm, can thus be pivoted by means of a joint so that its plane is preferably at an angle of up to 45 ° with respect to this longitudinal direction.

The grinding member or disc according to the invention is articulated to the arm rotating it so that the angle between the surface plane of the disc and the arm rotating it is free to change, preferably up to 45 °. In general, however, even a much smaller change in angle, even a change in angle of 5 to 25 °, is sufficient. The joint may be a cross or ball joint switch or some other joint suitably transmitting the above movement.

10

The grinding wheel which is pressed against the surface to be ground is thus automatically aligned with the surface of the surface to be ground when using the solution according to the invention, even if the angle of the hand-held power machine and the extension arm with respect to the surface 15 is changed, i.e. the machine is moved. Thus, in the solution according to the invention, it is not necessary to keep the grinding machine at a certain angle to the surface to be sanded, because the grinding wheel itself, due to the joint, settles in the correct position and constantly strives to follow the sanding surface in the correct position.

This is a particularly great advantage when sanding surfaces that are not easily accessible, such as sanding the roof or wall surfaces near the floor or roof edge.

- The extension arm allows the grinding wheel to reach the object to be sanded and - the joint puts the grinding wheel in the correct position.

30 Grinding with a rigid joint with an extension arm would not be possible. It would be almost impossible, due to the large radius provided by the extension arm, to control the angle of the grinding wheel and wall from a hand-held power machine. Even the slightest incorrect movement of the hands would appear as a groove in the surface to be sanded.

35 94500 5

The extension and fastening arms can preferably be formed of a shaft material, about 6-10 mm, preferably 8 mm of aluminum or steel bar. The extension arm should be long enough, usually more than 50 cm long, even more than 100 cm long.

5 Often, however, a stem 75 to 90 cm long is suitable. If necessary, the extension arm can be formed of two successive parts, a main part and a detachable extension part, whereby the machine can be operated with arms of different lengths.

10 The main purpose of the fastening arm is to direct the grinding wheel or the like attached to it at a suitable angle towards the surface to be sanded. The grinding wheel can, of course, be fitted at the end of a perfectly straight extension arm, in which case the grinder must either be held almost perpendicular to the grinding surface or the grinding wheel mounting joint must be able to turn the wheel at a very large angle for a good working position.

It has been found that a two-part arm, the mounting portion of which is preferably at an angle of 110 to 130 ° to the extension arm 20, is the preferred solution in most cases. In this case, for example, the upper part of the wall can be sanded in a suitable working position a short distance from the wall. At the same time, it is possible to press the grinding wheel with suitable pressure on the surface to be sanded. Sanding the roof is also easy with this machine.

25

For work safety and to protect the machine from dust, the rotating arm is protected, encapsulated, by a concentric cylindrical cover, e.g. an aluminum tube, preferably with a diameter of about 20 to 40 mm, which is bearing-30 in the cover, with ball and / or plain bearings. The joint connecting the grinding wheel to the mounting arm is preferably protected with a flexible rubber cover to prevent abrasive dust from causing difficulties. If desired, a vacuum cleaner or dust-absorbing hose can be connected to the machine.

35 94500 6

In the grinding machine, e.g. sandpaper rollers are used as the grinding material. A support wheel made of a rubber compound or other flexible material is preferably used as the base for the grinding wheels. The flexible support wheel presses the grinding wheel over a wide area and not just one angle, and thus the grinding mark is smoother than the mark created by a rigid disc. The grinding wheel is attached to the support wheel, for example with a velcro fastening. The grinder can also use a convex grinding wheel and a grinding wheel to grind curved surfaces.

10

If necessary, man-made fiber or metal brush discs, such as steel or brass brush discs, can be connected to the grinding device as grinding members. With steel brush discs, for example, rust can be effectively and easily removed from walls made of steel plates 15.

If necessary, a polishing pad in the form of an abrasive fiber or sheepskin can be used for the final glossing, e.g. for polishing a metal surface.

The invention will now be described in more detail by way of example with reference to the accompanying drawings. Figure 1 schematically illustrates a machine 25 according to the invention for wall grinding;

Figure 2 is a schematic side view of a device according to the invention;

Fig. 3 is a schematic cross-sectional view of the connection point of the extension arm of the machine 30 according to the invention and the power machine, and

Figure 4 is an enlarged schematic cross-sectional view of the connections of the fastening arm of the machine according to the invention to the extension arm and. 35 grinding wheels.

• · · «'· * = * Hit I. * I: i - 94500 7

Figure 1 shows a grinding machine 10 according to the invention in the working step of grinding the upper part of the wall 12. The person performing the grinding holds in his hands a power machine 14 to which a rotating grinding wheel 18 is rotatably attached to the end of the two-part arm part 16.

Figure 2 shows a grinder 10 according to the invention comprising a power machine 14, e.g. a drill, a two-piece shank 16 and a grinding wheel 18. The shank comprises an extension arm 20 axially connected to the power machine and a fastening arm 24 connected to it by a transmission joint 22, such as a universal joint or a tooth joint. The extension and fixing arms are protected by a tubular cover 26. The grinding wheel 18 is connected to the fixing arm 24 by a joint 15 28 so that the disc 18 pivots about the joint 28 in at least one plane, e.g. in the direction indicated by the arrows, and thus parallel to the plane of the surface to be ground. The grinding wheel comprises, for example, a support disc 30 made of rubber material and the actual grinding wheel 32. The short arm 34 in the middle of the support disc 30 is attached to the joint 28.

In addition to the conventional sandpaper grinding wheel 32, various brush discs, metal, steel or synthetic fiber brush discs, or soft polishing pads can be attached to the support wheel.

Figure 3 shows a cross-sectional view of the connection-30 of the extension arm 20 of the machine according to the invention and the power machine 14. The extension arm 20 is attached to the seat 36 of the power machine. The protective cover 26 is attached to the housing 40 of the power machine by a protective piece 38.

Figure 4 shows the connection of the mounting arm 24 to the extension 20 arm 20 and the grinding wheel support disc 30.

• 94500 8

The extension arm 20 is fitted to and secured to the protective housing 26 by roller bearings 42 and plain bearings 44, such as vinyl bearings. Correspondingly, the mounting arm 24 is protected by a protective cover 26 'and mounted on it by roller bearings 5 42.

A gear switch or joint 22 is arranged between the extension arm 20 and the mounting arm 24, which transmits the rotational movement of the extension arm to the mounting arm.

10

Attached to one end of the mounting arm 24 is a ball joint switch 46. The ball joint switch is also mounted to an arm 34 formed in the center of the grinding wheel support disc so that the grinding wheel is pivotable about the joint 15 and relative to the mounting arm 24.

The ball joint switch 46 is protected by a flexible rubber cover 48 from dust generated during grinding.

The invention is not intended to be limited to the embodiment described above, but is intended to be applicable in various embodiments within the scope of the inventive idea defined by the claims.

«M i

Claims (10)

A hand grinder (10) for the surface grinding of large planar surfaces (12), such as walls and ceilings, comprising: - a power machine (14), such as a drilling machine or a pneumatic machine, and - a shaft rotated by the power machine (14). a flat grinding wheel (18) movably connected to the power machine (14) of the flat grinding wheel (18) by a joint (28), such as a cross or ball joint switch (46), characterized in that - the arm (16) is two-part and consisting of - an extension arm (20) longer than 50 cm, fixed at its first end to the power machine for rotating the arm, and - an extension arm generally shorter and at an angle of> 90 °, the first end of which is connected by a transmission joint (22). rotatably at one end of the extension arm (20). Hand grinder according to Claim 1, characterized in that the grinding wheel (18) rotates at the same rotational speed as the extension arm (20). 25 Hand grinder according to Claim 1, characterized in that the extension arm (20) is 75 to 90 cm long. Hand grinder according to Claim 1, characterized in that the extension and fastening arms (20, 24) form an angle of 110 to 130 °, preferably an angle of 120 °. Hand grinder according to Claim 1, characterized in that the extension and fastening arms (20, 24) are essentially formed of about 6 to 10 mm, preferably 8 mm, of 94500 steel or aluminum bars. Hand grinder according to Claim 1, characterized in that the extension and fastening arms (20, 24) are protected by concentric cylindrical guards (26, 26 '), preferably with a diameter of about 20 to 40 mm, and are mounted shields with ball and / or plain bearings (42,44). Hand grinder according to Claim 1, characterized in that the joint (46) connecting the grinding wheel (18) to the fastening arm (24) is protected by a flexible rubber cover (48). Hand grinder according to Claim 1, characterized in that the extension arm (20) is formed by two successive parts, a main part and a detachable extension. Hand grinder according to Claim 1, characterized in that a suction hose for connecting dust is connected to the hand grinder in the vicinity of the grinding wheel (18). Hand grinder according to Claim 1, characterized in that the power machine (14) is a drilling machine with a rotation speed of <1000 rpm, preferably 300 to 700 rpm. ·· I - 94500