FIELD OF THE INVENTION The invention relates to a spade bit.

BACKGROUND OF THE INVENTION

Spade bits are known for drilling holes, typically rough-edged holes. Spade bits are typically used to drill holes in wood or wood like products. US5221166 (A) discloses a spade bit having a shank portion and a spade bit portion extending from the shank portion. The spade bit portion includes a spade portion with a planar region, and a centre tip concentric with a longitudinal axis and extending from the spade portion. First and second radial cutting edges extend from the centre tip toward first and second comer tips. First and second longitudinal cutting edges extend along longitudinal sides of the spade portion and terminate at the first and second comer tips. The first and second comer tips are located forward of the plane of the spade portion in the direction of rotation of the drill bit. The first and second radial cutting edges, and the first and second longitudinal cutting edges further include curved portions adjacent each of the first and second comer tips. A disadvantage of the spade bit of US5221166 (A) is that the hole fills up with material obscuring the view of the operator of the drilling tool driving the spade bit. A further disadvantage is that the loose material may hamper the cutting of other material from the hole. A further disadvantage is that the operator may need to remove the material from a freshly cut blind hole.

SUMMARY OF THE INVENTION

An object of the invention is to overcome one or more of the disadvantages mentioned above. According to a first aspect of the invention, a spade bit having a rotational axis, and comprising: - a shaft having a longitudinal axis aligned with the rotational axis, and comprising a proximal end configured for coupling to a driving tool, and a distal end; - a blade arranged to the distal end of the shaft and aligned with the longitudinal axis;

- a cutting edge arranged opposite the shaft and to the blade, and arranged for cutting away material from a hole; and

- at least one chip guide arranged to the blade, wherein the chip guide guides the cut away material from the drill hole and wherein the chip guide is shaped to change the direction of the cut away material to substantially outward from the hole.

A spade bit is a type of drill bit typically used for drilling holes in wood or wood like materials, such as laminates comprising wood layers. A spade bit has a rotational axis around which the spade bit rotates for cutting holes.

The spade bit comprises a shaft. The shaft has a longitudinal axis. The longitudinal axis and the rotational axis are typically aligned. The shaft is thus centred for providing rotational stability. The shaft comprises a proximal end and a distal end. The proximal end is shaped or configured for coupling to a driving tool. The spade bit further comprises a blade or spade. The blade is typically a rectangle. A side, typically a short side, of the blade is arranged or attached to the shaft. This attachment to the shaft is typically halfway the side. The spade bit further comprises a cutting edge arranged to an opposite side from the side attached to the shaft. The blade and/or cutting edges are typically arranged rotational symmetric to the rotational axis and/or longitudinal axis for providing mechanical stability to the spade bit while drilling.

The material is cut away by the cutting edge. Typically, the material cut away forms or produces chips, shavings, pieces, splints or shreds. This material just cut away therefore should become separated from the rest of the material forming the sides of the current hole. The rest of the material is typically solid or at least comprising a solid structure. As soon as the just cut away material becomes loose from the rest of the material, the material typically picks up rotational speed from the blade pushing the just cut away material around. The cut away material spinning around is typically only pushed towards the opening of the hole by new cut away material forming near the cutting edges. Thus, the hole typically fills with cut away material.

The cut away material typically encounters reasonable friction forces. As the at least one chip guide is arranged to the blade, the chip guide has the rotational speed of the blade. Depending on the distance between the chip guide and the rotational axis, the chip guide will have a particular velocity at a particular position. The blade pushes the cut away material in circles around the rotational axis. The friction working on the cut away material may cause a velocity difference between the typically constantly driven spade bit and the cut away material. This velocity difference may cause the just cut away material to collide, clash and/or strike the blade. At some location the cut away material encountering the velocity difference may collide with the chip guide instead of the blade. The chip guide is shaped to change the direction of the cut away material to substantially outward from the hole. This change will have the effect that cut away material is guided out of and/or away from the drill hole. This change may even have the effect of ejecting cut away material from the drill hole. Hence, the at least one chip guide provides the advantage of preventing cut away material from clogging the drill hole. The preventing of clogging may increase efficiency of drilling, preventing cutting edges from clogging and/or preventing that the drill hole has to be cleaned afterwards separately.

The at least one chip guide having the rotational speed of the blade may generate an air stream. This air stream may be impinging and/or strike on the spinning blade. The blade is typically substantially frontal or perpendicular to the air impinging on the blade. The chip guide changes this frontal impinging and/or striking of the air by guiding the air along the chip guide from frontal to substantially outward from the hole. Chips caught by and/or sucked into this air stream are transported, accelerated and/or ejected via this air stream outward from the hole. Hence, the at least one chip guide provides the advantage of preventing cut away material from clogging the drill hole. The preventing of clogging may increase efficiency of drilling, preventing cutting edges from clogging and/or preventing that the drill hole has to be cleaned separately.

In an embodiment of the invention, the chip guide comprises a ramp having a start and an end, wherein the angle of the end of the ramp is directed outward from the hole. A ramp may be a sloped surface. The sloped surface is typically sloped relative to a surface of the blade. The surface of the blade is typically the main surface of the blade or the frontal surface of the blade or the surface of the blade at least partly facing in the direction of rotation. Sloped is that it is having a different angle relative to the surface of the blade. The ramp is having a slope or shape with a start and an end. The slope, shape or angle of the end of the ramp is such that material just cut away, e.g. chip materials, following the ramp, preferably from the start to the end of the ramp, is advantageously provided with a direction outward from the hole.

In an embodiment of the invention, the start of the ramp is arranged proximal to the cutting edge and the end of the ramp is arranged distal to the cutting edge. The cutting edge are typically arranged for cutting or in contact with the bottom wall of the hole to be cut when drilling. Typically, the shaft is at least partly outside the hole when drilling. The shaft is arranged to the blade on an opposite side relative to the cutting edges. As the ramp is changing the direction of the just cut away material from the hole, the start of the ramp is advantageously closer to the cutting edges compared to the end of the ramp. This provides the advantage of giving the just cut away material a direction substantially outward from the hole.

In an embodiment of the invention, wherein the ramp comprises a first slope adjacent to the start of the ramp and a second slope adjacent to the end of the ramp; and wherein the second slope is angled more outward from the hole than the first slope. The second slope being more angled outward relative to the first slope provides the advantage of gradually or stepped wise changing the direction of the just cut away material which smoothens the change of the direction of travel of the just cut away material, which makes the change of direction more efficient. The technical effect may be that the just cut away material will exit the hole with a higher velocity.

The first slope and the second slope may gradually flow over in each other along the ramp. The first slope and the second slope may be stepped or incremental. The first slope may change toward the second slope by a combination of the preceding options. The more gradual or more smaller steps or increments, the more efficient the direction change of the cut away material.

In an embodiment of the invention, wherein the ramp comprises a slope starting at the start of the ramp and ending at the end of the ramp; and wherein the slope gradually angles more outward from the hole. This advantageously increases the efficiency of the change of direction of the cut away material outward from the hole.

In an embodiment of the invention, the chip guide is arranged eccentric from the rotational axis. The angular velocity or speed increases away from the rotational axis. Arranging the chip guide away from the rotational axis, which the same as arranging the chip guide eccentric, thus advantageously provides a rotational velocity to the chip guide. The chip guide having a rotational velocity provides the advantage that the chip guide obtains enough velocity relative to the cut away material that the velocity difference between the chip guide and the cut away material may be used to change the direction of this velocity difference such that the cut away material can substantially exit the hole. Furthermore, the more eccentric this chip guide is arranged from the rotational axis, the higher the centrifugal force the cut away material will experience. A balance should be found to arrange the chip guide such that the centrifugal force does not cause the cut away material to experience such a side way directed centrifugal force that even with the directional change from the chip guide, the cut away material cannot exit the hole. This effect of the cut away material not exiting the hole may be increased when the hole becomes deeper. This balance should therefore consider the typical depth of the hole for arranging the chip guide eccentric, but not at the side edge of the blade.

In an embodiment of the invention, the end of the ramp is twisted relative to the start of the ramp preferably with a lateral end of the end of the ramp towards the direction of rotation. Alternatively, the twist may be that the ramp is twisted relative to the longitudinal axis. In even another embodiment, the twist may be a combination of the two twist forms. The twist in the ramp allows the direction of the cut away material to be more efficiently changed. The twist in the ramp may advantageously counter the effect of the centrifugal force acting with a larger force on the cut away material farther away from the rotational axis. The twist in the ramp may advantageously counter the effect of the centrifugal force acting on the cut away material and providing it with a side way force, thus redirecting or changing the side way force to a substantially force or velocity outward from the hole. The twist in the ramp may be a gradually, but may also be stepped. In an embodiment of the invention, a medial part of the ramp is substantially straight, while the lateral end of the ramp is substantially twisted. This shape of the ramp advantageously more efficiently changes the direction of the cut away material.

In an embodiment of the invention, the chip guide is formed as part of the blade. This advantageously provides simply and/or efficiently to produce chip guide.

In an embodiment of the invention, the chip guide is a part punched out and formed from the blade. This advantageously provides a simply and/or efficient way of producing the chip guide.

In an embodiment of the invention, the blade comprises an opening, wherein the chip guide is arranged to the opening for guiding the material coming through the opening. The blade typically causes the cut away material to rotate in the hole. The opening in the blade provides a defined location where the cut away material may be arranged, aligned or line-up relative to the chip guide, typically arranged behind the opening.

In an embodiment of the invention, the opening is sized such that the size and/or shape of the opening prevents clogging with the cut away material while the cut away material passing through the opening gains enough velocity for exciting the hole. The size of the opening relative to the surface area of the blade is typically selected such that the whole of the cut away material rotating in front of the blade forces a portion of the cut away material through the opening for providing the cut away material forced through the opening by the rest of the cut away material to gain an initial velocity relative to the blade. The opening should also be small enough to allow the other cut away material to provide this pressure force to the cut away material going through the opening for obtaining this initial relative velocity. The opening should be large enough not to clog with cut away material. Thus, the size and/or shape of the opening in the blade should advantageously be such that the size of the opening prevents clogging while also gaining enough velocity for exciting the hole.

In an embodiment of the invention, the chip guide is shaped to change the direction of the cut away material to a substantially axial direction. The axial direction is typically the direction outward from the hole. The axial direction may be in the direction from the blade along the shaft. The axial direction may be from the cutting edge along the blade toward the shaft parallel to or coinciding with the rotational axis.

In an embodiment of the invention, the chip guide is shaped to change the direction of the cut away material from a substantially rotational direction to a substantially axial direction. The cut away material typically substantially follows a rotational path in front of the rotating blade in use. The blade may increase efficiency by allowing the cut away material to slide over the chip guide instead of impinging on the chip guide for changing the direction of the cut away material with the least friction for allowing the cut away material to have a higher velocity when releasing, coming loose or leaving the chip guide for the cut away material to more likely gaining enough velocity for exciting the hole, specifically even when the hole becomes deeper.

In an embodiment of the invention, the spade bit comprises a second chip guide arranged to the blade and symmetrical to the first chip guide relative to the rotational axis. The spade bit is advantageously kept symmetrical for allowing more balance when the spade bit is rotating, especially during drilling or making a hole. It is especially advantageous for the balance of the spade bit to have eccentric features, such as the chip guide, to be part of a balanced structure, such as by providing the same feature at an opposite side of the spade bit. In a further embodiment of the invention, the balanced features, such as the chip guides and/or the openings, are line symmetrical with regard to the rotational axis. In a further embodiment of the invention, the balanced features are arranged symmetrical to a plane perpendicular to the rotational axis.

In an embodiment of the invention, the chip guide is spaced apart from the cutting edge, preferably at least a quarter length of the cutting edge. The material of the blade between the cutting edge and the chip guide should advantageously provide enough strength to the cutting edge to not reduce the life expectancy of the cutting edge, the blade or the spade bit. Further, the material of the blade between the cutting edge and the chip should advantageously allow for enough cut away material such that the cut away material on the chip guide is pushed onto the chip guide According to another aspect of the invention, a spade bit comprising:

- a blade;

- at least one chip guide arranged to the blade, wherein the chip guide guides the material just cut away from the drill hole and wherein the chip guide is shaped to change the direction of the just cut away material to substantially outward from the hole.

In an embodiment of the invention, a spade bit, according to the preceding embodiment, wherein the spade bit is combined with any of the features introduced in the text or embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be apparent from and elucidated further with reference to the embodiments described by way of example in the following description and with reference to the accompanying drawings, in which:

Figure 1 schematically shows an isometric view of an embodiment of a spade bit 100;

Figure 2 schematically shows a detail of an isometric view of an embodiment of a spade bit 100 of Figure 1; and Figure 3 schematically shows a detail of an isometric top view of an embodiment of a spade bit 100 in figure 1.

The figures are purely diagrammatic and not drawn to scale. In the figures, elements which correspond to elements already described may have the same reference numerals.

LIST OF REFERENCE NUMERALS

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following figures may detail different embodiments. Embodiments can be combined to reach an enhanced or improved technical effect. These combined embodiments may be mentioned explicitly throughout the text, may be hint upon in the text or may be implicit.

Figure 1 schematically shows an isometric view of an embodiment of a spade bit 100. The spade bit comprises a shaft 105, a blade 110, cutting edges 115,

115’ and chip guides 120, 120’. The spade bit may comprise a centre point 130. The centre point may comprise a centre point flute 131 oriented in an axial direction across the surface of the centre point. If the centre point is absent, the cutting edges may form a single cutting edge. The spade bit may comprise a single chip guide instead of multiple or two chip guides. The spade bit typically comprises a coupling part 107 for coupling with a driving tool at a proximal end of the shaft. The shaft typically has a longitudinal axis E. The coupling part typically aligns with the shaft and the longitudinal axis E. The longitudinal axis E is typically during use in alignment with a rotational axis R of the spade bit, which is typically the same or substantially the same as the rotational axis of the driving tool driving the spade bit. The spade bit typically rotates around the rotational axis in a rotational direction D. The spade bit may be attached to an attachment part 106 at an opposite end of the shaft and/or distal end of the shaft. The attachment part may attach the blade to the shaft. The blade is typically symmetrically shaped relative to the rotational or the longitudinal axis. The centre point is typically symmetrically shaped relative to the rotational axis or the longitudinal axis.

Figure 2 schematically shows a detail of an isometric view of an embodiment of a spade bit 100 of Figure 1. The spade bit 100 comprises the blade and chip guides 120, 120’ arranged to the blade. Each of the chip guides comprises a ramp 121, 12G. Each of the ramps is shaped to guide impinging cut away material in use to slide along the ramp and change direction such that the cut away material is directed outward from the hole.

In this embodiment of the invention, the spade bit also comprises respective chip guide openings 126, 126’. The respective chip guide openings are typically arranged to the ramps for guiding cut away material coming through the opening in use to change direction along the chip guide for providing a direction to the cut away material coming through the opening that is outward from the hole. The respective chip guides may have start chip guides 122, 122’, which start of the chip guides are arranged close or proximal to the respective cutting edges. The respective chip guides may have end chip guides 123, 123, which end chip guides are arranged away of distal to the respective cutting edges. The chip guides may advantageously be made by punching out a part of the blade for thereby advantageously creating a ramp for the chip guide, while at the same time creating a chip guide opening for advantageously combining these features for a more optimal leading cut away material away, while also simplifying production of the spade bit.

The respective ramps of the respective chip guides may start with respective first slopes 124, 124’. The respective ramps of the respective chip guides may end with respective second slopes 125, 125’. The first slope is the slope where the cut away material starts to come in contact with the ramp. The second slope is the slope where the cut away material leaves the ramp and preferably or substantially has changed direction outward from the hole. The first slope is typically more aligned with the direction of travel of the cut away material before coming in contact with the ramp comprising this first slope. The cut away material coming in contact with the ramp, typically going through the opening has a direction of travel substantially perpendicular to a front surface of the blade. The front surface of the blade is facing into the direction of rotation of the blade. The second slope is typically more aligned with the direction of travel of the cut away material leaving the ramp and outward from the hole. The second slope typically allows the cut away material to slide along the second slope in a direction outward from the hole.

Figure 3 schematically shows a detail of an isometric top view of an embodiment of a spade bit 100 in figure 1. The respective ramps comprise a proximal end or side, which proximal end or side is proximal to the rotational axis. The respective ramps comprise a distal end or side, which distal end or side is distal to the rotational axis. A twist T in the ramp allows the ramp to counter the centrifugal force of the cut away material coming through the chip guide opening. The twist typically allows for cut away material travelling or sliding along the ramp to not leave the chip guide in a radial direction but more in an axial direction, which is typically a direction outward of the hole. The twist is typically in the range of 2-45 degrees, more specific 3-30 degrees, more specific 3-15 degrees, even more specific 5 degrees. The chip guide opening is typically having a height in the range of ¼ - ¾ of the height of the blade, more specific about ½ the height of the blade. The chip guide opening is typically having a width in the range of 1/8 - 7/8 of the distance of the side of the blade to the rotational axis, specifically, ¼ - 7/8 of the distance of the side of the blade to the rotational axis, more specifically, ½ - 7/8 of the distance of the side of the blade to the rotational axis, even more specifically, ¾ - 7/8 of the distance of the side of the blade to the rotational axis. The ramp, more specific the second slope, typically has an angle with a frontal surface of the blade in the range of 20-70 degrees, more specific 25-65 degrees, more specific 30-60 degrees, even more specific 35-55 degrees, even more specific about 45 degrees. The twist may also be seen in that the distal end and a medial part, arranged between the proximal and the distal end of the ramp, form a single flat surface having a single slope. The angle of this single slope or flat surface may be twisted radial or twisted relative to the longitudinal axis. The range of the twist angle for this twist is the same as the twist angle for the twist specified at the start of this paragraph. Figure 3 may be seen as comprising both types of twists.

The term “substantially” herein, such as in “substantially all emission” or in “substantially consists”, will be understood by the person skilled in the art. The term “substantially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially may also be removed. Where applicable, the term “substantially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. The term “comprise” includes also embodiments wherein the term “comprises” means “consists of’.

The term "functionally" will be understood by, and be clear to, a person skilled in the art. The term “substantially” as well as “functionally” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective functionally may also be removed. When used, for instance in “functionally parallel”, a skilled person will understand that the adjective “functionally” includes the term substantially as explained above. Functionally in particular is to be understood to include a configuration of features that allows these features to function as if the adjective “functionally” was not present. The term “functionally” is intended to cover variations in the feature to which it refers, and which variations are such that in the functional use of the feature, possibly in combination with other features it relates to in the invention, that combination of features is able to operate or function. For instance, if an antenna is functionally coupled or functionally connected to a communication device, received electromagnetic signals that are receives by the antenna can be used by the communication device. The word “functionally” as for instance used in “functionally parallel” is used to cover exactly parallel, but also the embodiments that are covered by the word “substantially” explained above. For instance, “functionally parallel” relates to embodiments that in operation function as if the parts are for instance parallel. This covers embodiments for which it is clear to a skilled person that it operates within its intended field of use as if it were parallel. Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

The devices or apparatus herein are amongst others described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation or devices in operation.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device or apparatus claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

The invention further applies to an apparatus or device comprising one or more of the characterising features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterising features described in the description and/or shown in the attached drawings.

The various aspects discussed in this patent can be combined in order to provide additional advantages. Furthermore, some of the features can form the basis for one or more divisional applications.