A guide element for a hand tool

Abstract

A guide element (101) for a hand tool comprises a body part (102) having an attachment section for attaching the guide element to the hand tool and a guide surface (104) for facing towards a workpiece (118) during usage of the hand tool The guide element comprises support balls (105) placed rotatably in cavities of the guide element so that the support balls protrude out from the guide surface and springs configured to push the support balls in a direction in which the support balls protrude out from the guide surface. The cavities are shaped to prevent the support balls from exiting from the cavities in the direction in which the support balls protrude out from the guide surface. The support balls have a mechanical contact with the workpiece during usage of the hand tool, and thus the guide element moves easily along a surface of the workpiece.

Description

[0001] A guide element for a hand tool

[0002] Technical field

[0003] The invention relates generally to machining with a hand tool that can be for example a beveler tool. More particularly, the invention relates to a guide element of a hand tool. Furthermore, the invention relates to a hand tool and to a method for assembling a guide element of a hand tool.

[0004] Background

[0005] Many hand tools, such as a beveler tool, comprise a machining head configured to machine a workpiece, a motor configured to run the machining head, and a guide element configured to keep the machining head in a desired posture with respect to the workpiece during usage of the hand tool to machine the workpiece. In many typical hand tools, e.g. a hand circular saw or a hand beveler tool, the guide element is a plate that slides along a surface of a workpiece when the hand tool is used for machining the workpiece. For example, the publication EP1340574 describes a beveler tool for creation of a chamfered border along a workpiece. The beveler tool of EP 1340574 comprises a guide plate to be positioned on top of an upper surface of the workpiece to be machined. A tilt position of the guide plate can be adjusted with respect to a machining head of the beveler tool.

[0006] The above-mentioned surface of the workpiece may however have rust and / or particles of impurity which change sliding properties between the surface of the workpiece and the guide element. Typically, the rust and / or impurity particles are not evenly spread over the surface of the workpiece but, instead, the surface of the workpiece has areas having more rust and / or impurity particles and other areas having less rust and / or impurity particles. Therefore, there is spatial variation in the sliding properties between the surface of the workpiece and the guide element. This makes it challenging to move the hand tool smoothly with a substantially constant speed along the surface of the workpiece. An uneven movement of the hand tool along the surface of the workpiece may lower the quality of a machining result. Summary

[0007] The following presents a simplified summary to provide a basic understanding of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying embodiments.

[0008] In this document, the word “geometric” when used as a prefix means a geometric concept that is not necessarily a part of any physical object. The geometric concept can be for example a geometric point, a straight or curved geometric line, a planar or non-planar geometric surface, a geometric space, or any other geometric entity that is zero, one, two, or three dimensional.

[0009] In accordance with the invention, there is provided a new guide element for a hand tool such as e.g. a beveler tool. The guide element according to the invention comprises:

[0010] - a body part having an attachment section for attaching the guide element to the hand tool and a guide surface for facing towards a workpiece during usage of the hand tool,

[0011] - support balls placed rotatably in cavities of the guide element so that the support balls protrude out from the guide surface, and

[0012] - springs configured to push the support balls in a direction in which the support balls protrude out from the guide surface, the cavities being shaped to prevent the support balls from exiting from the cavities in the direction in which the support balls protrude out from the guide surface.

[0013] The support balls have a mechanical contact with the workpiece during usage of the hand tool, and thus the guide element moves easily along a surface of the workpiece. This makes it easier to move the hand tool smoothly with a substantially constant speed along the surface of the workpiece. The even and smooth movement of the hand tool along the surface of the workpiece improves the quality of a machining result compared to a case in which the movement is uneven and not smooth.

[0014] In accordance with the invention, there is also provided a new hand tool, e.g. a beveler tool. The hand tool according to the invention comprises:

[0015] - a machining head configured to machine a workpiece,

[0016] - a motor configured to run the machining head, and

[0017] - a guide element according to the invention and configured to keep the machining head in a predetermined posture with respect to the workpiece during usage of the hand tool to machine the workpiece.

[0018] In accordance with the invention, there is also provided a new method for assembling a guide element according to an exemplifying and non-limiting embodiment where the body part comprises threaded through-holes and the guide element comprises plugs each having a threaded outer surface fit in the threaded through-holes and a hollow interior constituting the cavity containing one of the support balls and one of the springs. The method according to the invention comprises:

[0019] - inserting the plugs into the threaded through-holes of the body part,

[0020] - pressing a surface of a stencil element and the guide surface of the body part against each other, and

[0021] - turning the plugs to move the plugs in a first direction towards the stencil element until the support balls get mechanical contacts with the stencil element.

[0022] The surface of the stencil element facing towards the guide surface and the support balls has first surface areas to be against the guide surface and second surface areas to be against the support balls. The second surface areas are farther than the first surface areas in the first direction to allow the support balls protrude out from the guide surface in a situation in which the guide surface is against the first surface areas and the support balls are against the second surface areas. The height difference between the first and second surface areas of the stencil element determines a distance by which the support balls protrude out from the guide surface.

[0023] Exemplifying and non-limiting embodiments are described in accompanied dependent claims.

[0024] Various exemplifying and non-limiting embodiments both as to constructions and to methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplifying and nonlimiting embodiments when read in conjunction with the accompanying drawings.

[0025] The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of unrecited features.

[0026] The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated.

[0027] Furthermore, it is to be understood that the use of “a” or “an”, i.e. a singular form, throughout this document does not exclude a plurality.

[0028] Brief description of figures

[0029] Exemplifying and non-limiting embodiments and their advantages are explained in greater detail below in the sense of examples and with reference to the accompanying drawings, in which: figure 1 a illustrates a hand tool comprising a guide element according to an exemplifying and non-limiting embodiment, figures 1 b, 1 c, 1 d, and 1e illustrate the guide element of the hand tool shown in figure 1 a, figures 2a, 2b, 2c, 2d, 2e, and 2f illustrate details of guide elements according to exemplifying and non-limiting embodiments, figure 3 illustrates a hand tool comprising a guide element according to an exemplifying and non-limiting embodiment, figure 4 shows a flowchart of a method according to an exemplifying and non-limiting embodiment for assembling a guide element according to an exemplifying and nonlimiting embodiment, and figure 5 illustrates the method presented in figure 4.

[0030] Description of exemplifying and non-limiting embodiments

[0031] The specific examples provided in the description below should not be construed as limiting the scope and / or the applicability of the invention. Lists and groups of examples provided in the description are not exhaustive unless otherwise explicitly stated.

[0032] Figure 1 a shows a side-view of a hand tool according to an exemplifying and nonlimiting embodiment. In this exemplifying case, the hand tool is a beveler tool that comprises a machining head 113 configured to machine an edge of a workpiece 118, a motor 114 configured to run the machining head 113, and a guide element 101 according to an exemplifying and non-limiting embodiment. The guide element 101 is configured to keep the machining head 113 in a desired posture with respect to the workpiece 118 during usage of the hand tool. In this exemplifying case, the hand tool further comprises a guide roll 120 that facilitates keeping the hand tool in a desired posture with respect to the workpiece 118. The motor 114 can be for example an electric motor or a pneumatic motor. Figure 1 b shows a top-view of the guide element 101 , and figure 1 c shows a bottom view of the guide element 101. Figure 1d shows a section taken along a line A-A shown in figures 1 b and 1 c. The geometric section plane is parallel with the xz-plane of a coordinate system 199.

[0033] The guide element 101 comprises a body part 102 having an attachment section 103 for attaching the guide element 101 to a body of the hand tool. In this exemplifying case, the attachment section 103 has an aperture for a shaft of the machining head 113 and apertures for screws for attaching the guide element 101 to the body of the hand tool. The guide element 101 has a guide surface 104 for facing towards the workpiece 118 during usage of the hand tool. The guide element 101 comprises support balls placed rotatably in cavities of the guide element so that the support balls protrude out from the guide surface 104. In figures 1 a, 1 c, and 1 d, one of the support balls is denoted with a reference 105. The guide element 101 comprises springs configured to push the support balls in a direction in which the support balls protrude out from the guide surface 104. The cavities are shaped to prevent the support balls from exiting from the cavities in the direction in which the support balls protrude out from the guide surface. In figures 1 a-1 d, the direction in which the support balls protrude out from the guide surface 104 is the negative z- direction of the coordinate system 199.

[0034] In the exemplifying guide element 101 illustrated in figures 1 a-1 d, the body part 102 comprises threaded through-holes. Plugs having a threaded outer surface fit in the threaded through-holes are in the through-holes. In figure 1 d, one of the plugs is denoted with a reference 108. A section view of the plug 108 is shown in figure 1 e. The geometric section plane is parallel with the xz-plane of the coordinate system 199. The plug 108 has a hollow interior constituting the cavity containing the support balls 105 and a spring 106 configured to push the support ball 105 in the negative z-direction of the coordinate system 199. In this exemplifying case, the upper end of the plug 108 has a hexagonal cavity for a tool for rotating the plug 108. The plug 108 is locked at its desired portion with the aid of a nut 109. A distance s by which the support balls protrude out from the guide surface 104 can be for example in the range from 0.1 mm to 1 .5 mm, or in the range from 0.2 mm to 1 .2 mm.

[0035] In a guide element according to an exemplifying and non-limiting embodiment, the number of the support balls is at least 10. In a guide element according to an exemplifying and non-limiting embodiment, the number of the support balls is at least 15. In a guide element according to an exemplifying and non-limiting embodiment, the number of the support balls is at least 20. In a guide element according to an exemplifying and non-limiting embodiment, the number of the support balls is at least 25. In a guide element according to an exemplifying and non-limiting embodiment, the number of the support balls is at least 30. In a guide element according to an exemplifying and non-limiting embodiment, the number of the support balls is at least 35. In a guide element according to an exemplifying and non-limiting embodiment, the number of the support balls is at least 40. In a guide element according to an exemplifying and non-limiting embodiment, the number of the support balls is at least 45. In a guide element according to an exemplifying and non-limiting embodiment, the number of the support balls is at least 50.

[0036] In the exemplifying guide element 101 illustrated in figures 1 a-1 e, the number of the support balls is 48. In this exemplifying case, the support balls are located on two geometric circles concentric with the aperture for the shaft of the machining head. In figures 1 b and 1 c, the two geometric circles are depicted with dashed lines. As shown in figures 1 b and 1 c, the support balls are equidistantly on the circumference of each of the geometric circles.

[0037] In a guide element according to an exemplifying and non-limiting embodiment, the sum of tension forces of the springs pushing the support balls is at least 240 Newtons. In a guide element according to an exemplifying and non-limiting embodiment, the sum of tension forces of the springs pushing the support balls is at least 480 Newtons. In a guide element according to an exemplifying and nonlimiting embodiment, the sum of tension forces of the springs pushing the support balls is at least 720 Newtons. In the exemplifying guide element 101 illustrated in figures 1 a-1 e, the tension force of each of the springs can be in the range from e.g. 7 Newtons to 16 Newtons, and thus the sum of the tension forces can be in the range from 336 Newtons to 768 Newtons.

[0038] In a guide element according to an exemplifying and non-limiting embodiment, a ratio of a shortest distance between neighboring ones of the support balls to a diameter of the support balls is in the range from 3 to 8. The shortest distance between neighboring ones of the support balls is denoted with d in figure 1 c, and the diameter of the support balls is denoted with in figure 1 e. The shortest distance between neighboring ones of the support balls can be e.g. in the range from 10 mm to 30 mm, and the diameter of the support balls can be e.g. in the range from 3 mm to 10 mm.

[0039] In the exemplifying guide element 101 illustrated in figures 1 a-1 e, the body part 102 has openings one of which is denoted with a reference 119 in figures 1 b, 1 c, and 1 d. The openings reduce weight of the guide element 101 and enable a user of the hand tool to see a part of the workpiece 118 through the guide element 101 , and thus the openings facilitate the use of the hand tool. It is also possible to reduce the weight of a guide element by making some portions of the body part thinner than other portions. In the exemplifying guide element 101 illustrated in figures 1 a-1e, the thickness of the body part 102 is advantageously at least 6 mm to have sufficiently long threaded through holes for the plugs containing the support balls and the springs. Areas of the body part which are a distance, e.g. from 2 to 15 mm, away from the threaded through holes can be made thinner. It is to be however noted that the invention is not limited to any specific designs of the body part 102. In conjunction with many hand tools such as a beveler tool, the body part has advantageously a given minimum mass because the mass of the body part attenuates vibrations of the hand tool and thus the mass of the body part makes it healthier to use the hand tool.

[0040] Figure 2a illustrates a part of a guide element according to an exemplifying and nonlimiting embodiment. In this exemplifying case, the body part 102 has threaded through-holes each containing a plug having a threaded outer surface and containing a support ball and a spring. Figure 2a shows a section view of a plug 208a. The plug 208a is locked at its desired portion with the aid of a nut 209a. The plug 208a further contains an adjustable part 207a configured to enable adjustment of tension of a spring 206a independently of tensions of the other springs contained by the other plugs. In this exemplifying case, the plug 208a has a threaded inner surface and the adjustable part 207a is a pin having a threaded outer surface fit in the threaded inner surface of the plug 208a. An upper end of the adjustable part 207a may have e.g. a hexagonal cavity for a tool for rotating the adjustable part 207a. The adjustable part 207a can be locked to its desired position with e.g. gluetype locking material or the plug 208a can be provided with a mechanical locking element that prevents the adjustable part 207a from rotating with respect to the plug 208a.

[0041] Figure 2b illustrates a part of a guide element according to an exemplifying and nonlimiting embodiment. In this exemplifying case, the body part 102 has threaded through-holes each containing a plug having a threaded outer surface and containing a support ball and a spring. Figure 2b shows a section view of a plug 208b. The plug 208b is locked at its desired portion with the aid of a nut 209b. The plug 208b further contains a pin 207a having a threaded outer surface fit in a threaded inner surface of the plug 208b. An upper end of the pin 207b may have e.g. a hexagonal cavity for a tool for rotating the pin 207b. When the pin 207b has been tightened to its final position as shown in figure 2b, a spring 206b directs a predetermined force to a support ball 205b. The force can be changed by replacing the spring 206b with another spring having different properties.

[0042] Figure 2c illustrates a part of a guide element according to an exemplifying and nonlimiting embodiment. In this exemplifying case, the body part 102 has threaded through-holes each containing a plug having a threaded outer surface and containing a support ball and a spring. Figure 2c shows a section view of a plug 208c. The plug 208c is locked at its desired portion with the aid of a nut 209c. The plug 208c further contains an adjustable part 207c configured to enable adjustment of tension of a spring 206c independently of tensions of the other springs contained by the other plugs. In this exemplifying case, the plug 208c has a threaded inner surface and the adjustable part 207c is a pin having a threaded outer surface fit in the threaded inner surface of the plug 208c. An upper end of the adjustable part 207c may have e.g. a hexagonal cavity for a tool for rotating the adjustable part 207c. In this exemplifying case, the plug has a locking portion 211 made of nylon or some other suitable material which locks the adjustable part 207c at its desired position.

[0043] Figure 2d illustrates a part of a guide element according to an exemplifying and nonlimiting embodiment. In this exemplifying case, the body part 102 has threaded through-holes each containing a plug having a threaded outer surface and containing a support ball and a spring. Figure 2d shows a section view of a plug 208d. In this exemplifying case, the body part has a locking portion 212 made of nylon or some other suitable material which locks the plug 208d at its desired position. The plug 208c further contains an adjustable part 207d configured to enable adjustment of tension of a spring 206d independently of tensions of the other springs contained by the other plugs. In this exemplifying case, the plug 208d has a threaded inner surface and the adjustable part 207d is a pin having a threaded outer surface fit in the threaded inner surface of the plug 208d. An upper end of the adjustable part 207d may have e.g. a hexagonal cavity for a tool for rotating the adjustable part 207d. In this exemplifying case, the plug has a locking portion 222 made of nylon or some other suitable material which locks the adjustable part 207d at its desired position.

[0044] Figure 2e illustrates a part of a guide element according to an exemplifying and nonlimiting embodiment. In this exemplifying case, the body part 102 has threaded through-holes each having a tapering end-section and containing a support ball, a spring directing a force to the support ball, and an adjustable part configured to enable adjustment of tension of the spring. Figure 2e shows a section view of an adjustable part 207e configured to enable adjustment of tension of a spring 206e independently of tensions of the other springs contained by the other through-holes of the body part 102. The spring 206e pushes a support ball 205e against a tapering end-section 221 of the through hole so that the support ball 205e protrudes out from the guide surface 104. The adjustable part 207e is locked at its desired portion with the aid of a nut 209e.

[0045] Figure 2f illustrates a part of a guide element according to an exemplifying and nonlimiting embodiment. In this exemplifying case, the body part 102 has threaded through-holes each containing a plug having a threaded outer surface and containing a support ball and a spring. Figure 2f shows a section view of a plug 208f. The length of a part 223 the plug 208f has been selected so that a support ball 205f protrudes a desired distance s out from the guide surface 104 when the plug 208f has been tightened against the upper surface of the body part 102. In this exemplifying case, the tension of a spring 206f is not adjustable, but the plug 208f can be provided with an adjustable part configured to enable adjustment of the tension of the spring 206f.

[0046] Figure 3 shows a side-view of a hand tool according to an exemplifying and nonlimiting embodiment. In this exemplifying case, the hand tool is a beveler tool that comprises a machining head 313 configured to machine an edge of a workpiece 318, a motor 314 configured to run the machining head 313, and a guide element 301 according to an exemplifying and non-limiting embodiment. The guide element 301 is configured to keep the machining head 313 in a desired posture with respect to the workpiece 318 during usage of the hand tool. The guide element 301 comprises a body part 302 having an attachment section for attaching the guide element 301 to a body of the hand tool. The guide element 301 has a guide surface 304 for facing towards the workpiece 318 during usage of the hand tool. In this exemplifying case, the body part 302 has an L-shaped profile such that the guide surface 304 has two sections which are substantially perpendicular to each other. The guide element 301 comprises support balls placed rotatably in cavities of the guide element so that the support balls protrude out from the guide surface 304. The guide element 301 comprises springs configured to push each support ball in a direction in which the support ball under consideration protrudes out from the guide surface 304. The cavities are shaped to prevent each support ball from exiting from the respective cavity in the direction in which the support ball protrudes out from the guide surface. Mechanical suspension arrangements of the support balls can be for example such as presented above with reference to any of figures 1 e and 2a-2f.

[0047] Figure 4 shows a flowchart of a method for assembling a guide element according to an exemplifying and non-limiting embodiment where the body part comprises threaded through-holes and the guide element comprises plugs each having a threaded outer surface fit in the threaded through-holes and a hollow interior constituting the cavity containing one of the support balls and one of the springs. Figure 5 illustrates the method presented in figure 4. The method comprises the following actions:

[0048] - action 401 : inserting the plugs, such as plugs 508a, 508b, 508c, and 508d shown in figure 5, into the threaded through-holes of the body part 501 ,

[0049] - action 402: pressing a surface of a stencil element 515 and the guide surface 504 of the body part 501 against each other, and

[0050] - action 403: turning the plugs to move the plugs in a first direction towards the stencil element 515 until the support balls get mechanical contacts with the stencil element.

[0051] The surface of the stencil element 515 facing towards the guide surface 504 and the support balls has first surface areas, such as a surface area 516, to be against the guide surface and second surface areas, such as a surface area 517, to be against the support balls. The second surface areas are farther than the first surface areas in the first direction to allow the support balls protrude out from the guide surface 504 in a situation in which the guide surface is against the first surface areas and the support balls are against the second surface areas. The height difference between the first and second surface areas determines a distance by which the support balls protrude out from the guide surface.

[0052] In the exemplifying situation shown in figure 5, the installation of the plug 508a is ready and the plug 508a has been locked at its position with a nut 509a. The plug 508b is at its desired position but the plug 508b has not yet been locked with a nut 509b. The plugs 508c and 508d have not yet been driven to their desired positions. The specific examples provided in the description given above should not be construed as limiting the scope and / or the applicability of the invention. It is to be noted that lists and groups of examples given in this document are non-exhaustive lists and groups unless otherwise explicitly stated.

Claims

What is claimed is:1 . A guide element (101 , 301 , 501 ) for a hand tool, the guide element comprising:- a body part (102, 302, 502) having an attachment section (103) for attaching the guide element to the hand tool and a guide surface (104, 304, 404) for facing towards a workpiece during usage of the hand tool, and- support balls (105, 205) placed rotatably in cavities of the guide element so that the support balls protrude out from the guide surface, characterized in that the guide element comprises:- springs (106, 206a-206f) configured to push the support balls in a direction (— z) in which the support balls protrude out from the guide surface, the cavities being shaped to prevent the support balls from exiting from the cavities in the direction in which the support balls protrude out from the guide surface.

2. A guide element according to claim 1 , wherein the guide element comprises adjustable parts (207a, 207c, 207d, 207e) configured to enable adjustment of tension of each spring independently of tensions of the other springs.

3. A guide element according to claim 1 or 2, wherein a sum of tension forces of the springs pushing the support balls is at least 240 Newtons.

4. A guide element according to claim 1 or 2, wherein a sum of tension forces of the springs pushing the support balls is at least 480 Newtons.

5. A guide element according to claim 1 or 2, wherein a sum of tension forces of the springs pushing the support balls is at least 720 Newtons.

6. A guide element according to any one of claims 1 -5, wherein a distance (s) by which the support balls protrude out from the guide surface (104) is in a range from 0.1 mm to 1.5 mm.

7. A guide element according to claim 6, wherein the distance (s) is in a range from 0.2 mm to 1.2 mm.

8. A guide element according to any one of claims 1 -7, wherein a number of the support balls is at least 20.

9. A guide element according to claim 8, wherein the number of the support balls is at least 45.

10. A guide element according to any one of claims 1 -9, wherein a ratio of a shortest distance (d) between neighboring ones of the support balls to a diameter ( of the support balls is in a range from 3 to 8.

11. A guide element according to any one of claims 1 -10, wherein the attachment section (103) has an aperture for a shaft of a machining head of the hand tool, and the support balls (105) are located on one or more geometric circles concentric with the aperture of the attachment section.

12. A guide element according to claim 11 , wherein, on each of the one or more geometric circles, the support balls are equidistantly on a circumference of the geometric circle.

13. A guide element according to any one of claims 1 -12, wherein the body part comprises threaded through-holes and the guide element comprises plugs (108, 208a, 208b, 208c, 208d, 208f, 508a-508d) each having a threaded outer surface fit in the threaded through-holes and a hollow interior constituting the cavity containing one of the support balls (105, 205a, 205b, 205c, 205d, 205f) and one of the springs (106, 206a, 206b, 206c, 206d, 206f).

14. A hand tool comprising:- a machining head (113, 313) configured to machine a workpiece,- a motor (114, 314) configured to run the machining head, and- a guide element (101 , 301 ) according to any one of claims 1-13 and configured to keep the machining head in a predetermined posture with respect to the workpiece during usage of the hand tool to machine the workpiece.

15. A method for assembling a guide element according to claim 13, the method comprising:- inserting (401 ) the plugs (508a-508d) into the threaded through-holes of the body part (502), - pressing (402) a surface of a stencil element (515) and the guide surface(504) of the body part against each other, and- turning (403) the plugs (508a-508d) to move the plugs in a first direction (-z) towards the stencil element until the support balls get mechanical contacts with the stencil element, characterized in that the surface of the stencil element facing towards the guide surface and the support balls has first surface areas (516) to be against the guide surface and second surface areas (517) to be against the support balls, wherein the second surface areas are farther than the first surface areas in the first direction to allow the support balls protrude out from the guide surface in a situation in which the guide surface is against the first surface areas and the support balls are against the second surface areas.

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