Patent Publication Number: US-2023148747-A1

Title: Set of panels with a mechanical locking device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. application Ser. No. 16/553,325, filed on Aug. 28, 2019, which claims the benefit of Swedish Application No. 1851028-9, filed on Aug. 30, 2018. The entire contents of each of U.S. application Ser. No. 16/553,325 and Swedish Application No. 1851028-9 are hereby incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     Embodiments of the present invention relate to panels that may be arranged perpendicular to each other and locked together with a mechanical locking device. The panels may be assembled and locked together to obtain a furniture product, such as a bookshelf, a cupboard, a wardrobe, a box, a drawer or a furniture component. 
     TECHNICAL BACKGROUND 
     A furniture product provided with a mechanical locking device is known in the art, as evidenced by WO2015/038059. The furniture product comprises a first panel connected perpendicular to a second panel by a mechanical locking device comprising a flexible tongue in an insertion groove. 
     The above description of various known aspects is the applicant&#39;s characterization of such, and is not an admission that any of the above description is considered as prior art. 
     Embodiments of the present invention address a need to provide panels that may be easily assembled. 
     SUMMARY 
     It is an object of certain aspects of the present invention to provide an improvement over the above described techniques and known art; particularly to facilitate assembling of panels configured to be assembled without the need of using any tools. 
     A further object of at least certain aspects of the present invention is to facilitate assembling of panels configured to be assembled with a locking device that is easy to manufacture and to use, which reduces the risk of incorrect installation thereof. 
     A further object of at least certain aspects of the present invention is to facilitate assembling of panels configured to be assembled in a more stable and aesthetic way. 
     At least some of these and other objects and advantages that will be apparent from the description have been achieved by a set comprising a first panel, a second panel and a mechanical locking device for locking the first panel to the second panel, wherein the first panel comprises a first edge surface and a first panel surface, the second panel comprises a second panel surface, the first edge surface is facing and/or is parallel with the second panel surface in a locked position of the first and the second panel, the mechanical locking device comprises at least one rod-shaped element at the first edge surface and at least one insertion groove at the second panel surface, the rod-shaped element is configured to be inserted into the insertion groove, the rod-shaped element extends at a first angle from the first edge surface, the insertion groove extends into the second panel surface at an angle from the second panel surface, the mechanical locking device further comprises at least one locking groove at the first edge surface or at the second panel surface and at least one locking part, wherein the locking groove comprises at least one locking surface extending at a third angle from the first edge surface or from the second panel surface, the locking part is configured to be inserted into the locking groove and lock against the locking surface, and the third angle is different than the first angle. 
     According to an aspect the mechanical locking device is configured to obtain the locked position by displacing first panel relative the second panel in an assembly direction which is essentially parallel with the first panel surface. 
     According to an aspect the third angle is about 45° to about 90° larger than the first angle. 
     According to an aspect the locking part is positioned at the first edge surface or at the second panel surface and the locking groove is positioned at the opposite second panel surface or first edge surface. 
     According to an aspect the first angle is within the range of about 30° to about 60, or within the range of about 40° to about 50, or about 45°. 
     According to an aspect the assembly direction is essentially parallel with at least one of the first angle and the second angle. 
     According to an aspect the locking part is flexible. 
     According to an aspect the locking part, in an unflexed/non-compressed state, is configured to be positioned partly in the locking groove. 
     According to an aspect the locking part comprises a spring. 
     According to an aspect the locking part is arranged in a locking part groove on the first edge surface or on the second panel surface. 
     According to an aspect the locking part, in a flexed/compressed state, is configured to be substantially positioned in the locking part groove. 
     According to an aspect the insertion groove and/or the locking groove is a drill hole. 
     According to an aspect the drill hole is a bottom-ended drill hole. 
     According to an aspect the rod-shaped element is arranged in a rod element groove in the first edge surface. 
     According to an aspect the set comprises a first panel groove on the first panel surface on the first panel and a second panel groove on the second panel surface of the second panel. 
     According to an aspect a width of the first panel groove is essentially the same as a width of the second panel groove. 
     According to an aspect the set further comprises a back panel configured to be inserted in, and optionally to cooperate with, the first and second panel groove. 
     According to an aspect the first panel comprises a second edge surface, the second panel comprises a third edge surface, the first panel groove is substantially parallel to the second edge surface and the second panel groove is substantially parallel to the third edge surface. 
     According to an aspect the first panel groove extends substantially along the entire second edge surface and the second panel groove extends essentially along the entire third edge surface. 
     According to an aspect the first panel groove and/or the second panel groove is bottom-ended. 
     According to an aspect an extension of the back panel from the first edge of the first panel, when one first panel, one second panel, and one back panel have been assembled, is less than an extension of the rod shaped element from the first edge surface. 
     According to an aspect the core of the first panel and/or of the second panel may be a wood-based core, such as MDF, HDF, OSB, WPC, plywood or particleboard. The core may also be a plastic core comprising thermosetting plastic or thermoplastic, e.g., vinyl, PVC, PU or PET. The plastic core may comprise fillers. 
     The first panel and/or the second panel may also be of solid wood. 
     The first panel and/or the second panel may be provided with a decorative layer, such as a foil or a veneer, on one or more surfaces. 
     At least some of the above identified and other objects and advantages that may be apparent from the description have been achieved by a locking device for a furniture product in accordance with the above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other aspects, features and advantages of which embodiments of the invention are capable of, will be apparent and elucidated from the following description of embodiments and aspects of the present invention, reference being made to the accompanying drawings, in which 
         FIG.  1    shows a 3D view from above of a set in an unassembled state of an aspect of the invention. 
         FIG.  2    shows a 3D view from above of a set in an unassembled state of an aspect of the invention. 
         FIG.  3    shows a 3D view from above of a set in an unassembled state of an aspect of the invention. 
         FIG.  4    shows a 3D side view of a set in an assembled state of an aspect of the invention. 
         FIG.  5 A  shows a side view of a set in an unassembled state of an aspect of the invention. 
         FIG.  5 B  shows a side view of an embodiment of the rod-shaped element 
         FIG.  6    shows a side view of a set in an assembled state of an aspect of the invention. 
         FIG.  7    shows a side view of a set in an unassembled state of an aspect of the invention. 
         FIG.  8    shows an enlargement of part of the view shown in  FIG.  7   . 
         FIG.  9    shows a side view of a set in an assembled state of an aspect of the invention. 
         FIG.  10    shows an enlargement of part of the set shown in  FIG.  9   . 
         FIG.  11    shows a view of a set comprising two of the first panel, two of the second panel and one back panel in an unassembled state of an aspect of the invention. 
         FIG.  12    shows a side view of a set in an assembled state of an aspect of the invention. 
         FIG.  13    shows an enlargement of part of the set shown in  FIG.  12   . 
         FIG.  14    shows an enlargement of part of the set shown in  FIG.  12   . 
         FIG.  15    shows a side view of an embodiment of first panel. 
         FIG.  16    shows a view of a set comprising two of the first panel, two of the second in an unassembled state of an aspect of the invention. 
         FIGS.  17 A- 17 D  show enlargements of parts of a set during assembling. 
     
    
    
     DETAILED DESCRIPTION 
     Specific embodiments of the invention will now be described with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The terminology used in the detailed description of the embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like numbers refer to like elements. 
     The terminology used herein is for the purpose of describing particular aspects of the disclosure only, and is not intended to limit the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. 
     In the drawings and specification, there have been disclosed exemplary aspects of the disclosure. However, many variations and modifications may be made to these aspects without substantially departing from the principles of the present disclosure. Thus, the disclosure should be regarded as illustrative rather than restrictive, and not as being limited to the particular aspects discussed above. Accordingly, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, for example, definition of dimensions such as width or breadth or height or length or diameter depends on how exemplary aspects are depicted, hence, if depicted differently, a shown width or diameter in one depiction is a length or thickness in another depiction. 
     It should be noted that the word “comprising” does not necessarily exclude the presence of other elements or steps than those listed and the words “a” or “an” preceding an element do not exclude the presence of a plurality of such elements. It should further be noted that any reference signs do not limit the scope of the claims, that the example aspects may be implemented at least in part by means of both hardware and software, and that several “means”, “units” or “devices” may be represented by the same item of hardware. 
     The different aspects, alternatives and embodiments of the invention disclosed herein may be combined with one or more of the other aspects, alternatives and embodiments described herein. Two or more aspects may be combined. 
     Embodiments of the invention are shown in  FIGS.  1 - 16    including a set comprising a first panel  10 , a second panel  20  and a mechanical locking device for locking of the first panel  10  to the second panel  20 . The first panel  10  comprises a first edge surface  11  and a first panel surface  13 . The second panel  20  comprises a second panel surface  22 . The first edge surface  11  is facing or parallel to the second panel surface  22  in a locked position of the first and the second panel  10 ,  20 . The mechanical locking device comprises at least one element  31  at the first edge surface  11  and at least one insertion groove  32  at the second panel surface  22 . The element  31  may be rod-shaped. The rod-shaped element  31  is configured to be inserted into the insertion groove  32 . The rod-shaped element  31  extends at a first angle α 1  from the first edge surface  11  and the insertion groove  32  extends into the second panel surface  22  at a second angle α 2  from the second panel surface  22 . When there are more than one element  31 , each element  31  may be arranged parallel to each other element  31 . When there are more than one insertion grooves  32 , each insertion groove  32  may be arranged parallel to each other insertion groove  32 . The mechanical locking device further comprises at least one locking groove  35  at the first edge surface  11  or at the second panel surface  22  and at least one locking part  34 . The locking groove  35  comprises at least one locking surface  37  extending at a third angle β from the first edge surface  11  or from the second panel surface  22 . The locking part  34  is configured to be inserted into the locking groove  35  and lock against the locking surface  37 , and the third angle β is different than the first angle α 1 . 
     The first panel  10  and the second panel  20  may be panels for a furniture product and may be a part of a frame of a furniture product. 
     The set may be configured for locking the first panel  10  to the second panel  20  with the first panel surface  13  perpendicular or essentially perpendicular to the second panel surface  22 . 
     The second panel  20  may comprise a fourth edge surface  25  and the insertion groove  32  may be positioned adjacent the fourth edge surface  25 . The set may be configured for locking the first panel  10  to the second panel  20  with the first panel surface  13  parallel or essentially parallel to the fourth edge surface  25 . 
       FIGS.  1 - 3 ,  5 A,  7 - 8 ,  11 , and  16    disclose a set according to an aspect in an unassembled state.  FIGS.  4 ,  6 ,  9 - 10 , and  12 - 14    disclose a set according to an aspect in an assembled state. The set may be assembled by a displacement of the first panel  10  relative the second panel  20  in an assembly direction  111 ,  112 ,  114  which is essentially parallel with the first panel surface  13 . The mechanical locking device may be configured to automatically lock the first panel  10  to the second panel  20  when the rod-shaped element  31  is inserted into the insertion groove  32  and the locking part  34  is inserted into the locking groove  35  and locks against the locking surface  37 . The set may be locked when the first edge surface  11  is arranged against the second panel surface  22 . 
     The third angle β may be about 45° to about 90° larger than the first angle α 1  and/or the second angle α 2 . 
     The locking part  34  may be positioned at the first edge surface  11  or at the second panel surface  22  and the locking groove  35  may be positioned at the opposite second panel surface  22  or the first edge surface  11 . 
     The first angle α 1  and/or the second angle α 2  may be within the range of about 30° to 60°, or within the range of about 40° to 50°, or about 45°. The first angle α 1  and the second angle α 2  may be parallel or essentially parallel. 
     The assembly direction  111 ,  112 ,  114  may be essentially parallel with the first angle α 1  and/or the second angle α 2 . 
     The third angle β of the locking surface  37  may be within the range of about 70° to 110°, or within the range of about 80° to 100°, or within the range of about 85° to 95°, or about 90°. 
     The locking part  34  may be flexible. 
     The locking part  34 , in an unflexed/non-compressed state, may be configured to be positioned partly in the locking groove  35 . 
     The locking part  34  may comprise a spring. 
     The locking part  34  may be arranged in a locking part groove  38  on the first edge surface  11  or on the second panel surface  22 . 
     The locking part  34 , in a flexed/compressed state, may be configured to be substantially positioned in the locking part groove  38 . 
     When the first  10  and second  20  panels are assembled together the locking part  34  may be compressed and is substantially positioned in the locking part groove  38 . The locking part  34  may comprise a spring that facilitates the compression of the locking part  34 . When the first panel  10  is displaced in relation to the second panel  20  in the assembly direction, the rod-shaped element  31  becomes inserted into the insertion groove  32 . When the locking part  34  meets the locking groove  35  the locking part  34  may expand out from the locking part groove  38  and protrude into the locking groove  35 . The first panel  10  and second panel  20  will then be locked together, since the positioning of a part of the locking part  34  in the locking groove  35  hinders the first panel  10  from being displaced in relation to the second panel  20  in a direction opposite to the assembly direction. 
     The insertion groove  32  and/or the locking groove  35  may be a drill hole. The drill hole may be a bottom-ended drill hole. 
     The insertion groove  32  may have a diameter D 2 . 
     The insertion groove  32  may comprise a chamfer  60  or a rounding, which is configured to guide the rod shaped element during assembling, as shown in  FIG.  8   . 
     The rod-shaped element  31  may be arranged in a rod element groove  36  on the first edge surface  11  on the first panel  10  or on the second panel surface  22  on the second panel  20 . 
     The rod-shaped element  31  may have a diameter D 1 . The diameter D 2  of the insertion groove  32  may be larger than the diameter D 1  of the rod-shaped element  31 . The diameter D 2  of the insertion groove  32  may be about 0.3 to about 0.8 mm larger than the diameter D 1  of the rod-shaped element  31  for optimal assembly. 
     According to an aspect the set may comprise a first panel groove  12  on the first panel surface  13  on the first panel  10  and/or a second panel groove  23  on the second panel surface  22  of the second panel  20 . 
     The first panel groove  12  on the first panel surface  13  may comprise a width W 1 . 
     The second panel groove  23  on the second panel surface  22  may comprise a width W 2 . 
     The width W 1  of the first panel groove  12  may be essentially the same as the width W 2  of the second panel groove  23 . 
     The set may further comprise a back panel  40 . The back panel  40  may be configured to be inserted in, and optionally cooperate with, the first panel groove  12  and the second panel groove  23 . 
       FIG.  6    shows that the back panel  40  may be assembled to the first  10  and second  20  panel by displacing the back panel  40  relative the first  10  and second  20  panel in an assembly direction  113  which is essentially perpendicular to the second panel surface  22  of the second panel  20 . A thickness T of the back panel  40  may be essentially the same as the width W 1 , W 2  of the first  12  and/or second  23  panel groove. 
     There may be a play between the back panel  40  and the first  12  and/or second  23  panel groove which may facilitate a displacement of an edge of the back panel  40  in the first  12  and/or second  23  panel grooves. The play may be in the range of about 0 mm to about 0.5 mm, or about 0.1 mm to about 0.2 mm. 
     In one aspect the width W 1 , W 2  of the first  12  and/or second  23  panel groove minus a thickness T of the back panel  40 , i.e., ΔW, is equal to or larger than an extension H of the back panel  40  in relation to the first panel  10  or second panel  20  after a first panel  10 , a second panel  20  and a back panel  40  have been assembled, i.e., ΔW≥H, see  FIGS.  12 - 15   . 
       FIG.  13    shows an embodiment comprising a positioning element  50 , for positioning the back panel  40  relative the first  12  and/or second  23  panel groove. The positioning element  50  may comprise a first wedge element  51  and second wedge element  52 . 
     In one aspect H is less than an extension D of the rod shaped element  31  from the first edge surface  11 . 
     The rod shaped element  31  may have an extension E along the first edge surface  11 . 
     In one aspect, if a set comprising two of the first panel  10  and two of the second panel  20  are to be assembled, at least one panel  10 ,  20  may have a width W 1 , W 2  of the first  12  and/or second  23  panel groove that allows for a displacement of the extension H of the back panel  40  within the first  12  and/or second  23  panel groove. The displacement may be equal to or larger than ΔW. In one aspect, all panels  10 ,  20  have the same width W 1 , W 2  of the first  12  and second  23  panel groove to facilitate the production of the panels. 
     A length of the back panel  40  may designed to avoid the extension H of the back panel  40 . 
     An edge of the back panel  40  may be essentially flush with the first edge  11  surface of the first panel  10   
       FIG.  15    shows a side view of an embodiment of first panel  10  with the first  12  panel groove. The first  12  panel groove may comprise a width W 1  and a height H 1 . The first panel  10  may comprise a second edge surface  14  and the second panel  20  may comprise a third edge surface  24 . The first panel groove  12  may be substantially parallel to the second edge surface  14  and the second panel groove  23  may be substantially parallel to the third edge surface  24 . 
     The first panel groove  12  may extend substantially along the entire second edge surface  14  and the second panel groove  23  may extend essentially along the entire third edge surface  24 . 
     The first panel groove  12  and/or the second panel groove  23  may be bottom-ended. 
     The first  12  and/or second  23  panel groove may be formed by mechanical cutting, such as milling or sawing. 
     The first panel groove  12  may be formed in the first panel surface  13  and in a core of the first panel  10 . The second panel groove  23  may be formed in the second panel surface  22  and in a core of the second panel  20 . 
     The first edge surface  11  may comprise two or more of said rod-shaped element  31  and the second panel surface  22  may comprise two or more of said insertion groove  32 , and vice versa, which may be arranged linearly, wherein each of the rod-shaped elements  31  is configured to be inserted into one insertion groove  32 . 
     A locking of the first panel  10  to the second panel  20  in a direction which is parallel with the second panel surface  22  may be obtained by the locking part  34  being inserted into the locking groove  35  and locking against the locking surface  37 . The locking surface extends at the third angle β from the first edge surface  11 , where third angle β is about 45° to about 90° larger than the first angle α 1 . 
     A cross cut of the insertion groove  32 , in a plane parallel to the second panel surface  22 , may have a shape that matches a cross cut of the rod-shaped element  31 , in a plane parallel to the first edge surface  11 . An advantage of this may be that an improved locking of the first panel  10  to the second panel  20  is obtained and that the assembly of the set of panels is done easily. 
     The rod-shaped element  31  and the insertion groove  32  are disclosed more in detail in  FIGS.  5 A- 8  and  10   , which show cross cuts along the rod-shaped element  31  and the insertion groove  32 . 
       FIG.  5 A  shows an embodiment of the locking part  34  comprising a guiding surface  87  at outer edge of the locking part  34 . The guiding surface is configured to cooperate with an outer edge the locking groove  35  during the insertion of locking part  34  into the locking groove  35 . 
       FIG.  5 B  shows an embodiment of the rod-shaped element  31  which may be of an elongated shape and comprise a length direction  86 , a width direction  85  and a centre line  81  extending in the length direction. According to an aspect the rod-shaped element  31  is configured to be inserted in the rod element groove  36  on the first edge surface  11 . 
     According to an aspect the rod-shaped element  31  is configured to be inserted in the rod element groove  36  on the second panel surface  22 . 
     According to an aspect the rod-shaped element  31  may be configured to be attached in the rod element groove  36  by friction. 
     According to an aspect the rod-shaped element  31  may be configured to be glued in the rod element groove  36 . 
     According to an aspect the rod-shaped element  31 , the rod element groove  36  and the insertion groove  32  may have a substantially circular shape, although other shapes, such as triangular, rectangular, square, etc. are possible. 
     According to one aspect the locking groove  35  and the locking part  34  may have a substantially circular shape, although other shapes, such as triangular, rectangular, square, etc. are possible. 
     According to an aspect, which is shown in  FIG.  7   , a first edge surface  11  may have at least one element  31 , while the opposite edge surface may have at least one insertion groove  32 . 
     According to a further aspect, a first edge surface  11  may have a combination of at least one element  31  and at least one insertion groove  32 . A corresponding second panel surface  22  may have a corresponding combination of at least one insertion groove  32  and at least one element  31 . 
     According to an aspect, which is shown in  FIG.  8   , the position of at least one rod shaped element  31  may be positioned at first distance  83  from the second edge surface  14 . The first distance may be measured from the second edge surface  14  to a centre line  81  of the rod shaped element  31 . The corresponding insertion groove  32  may be positioned at a second distance  84  from the third edge surface  24 . The second distance may be measured from the third edge surface  24  to a centre line  82  of the insertion groove  32 . The first distance may be different from the second distance which may increase the locking force. 
     The difference between the first distance and the second distance may be in the range of about 0.1 mm to about 0.5 mm. 
     According to an aspect the rod-shaped element  31  is made from one or more of a wood based material, a polymer material, which may comprise reinforcement, such as glass fibre or a metal. 
     According to an aspect the rod shaped element  31  may have a waxed surface to facilitate assembly. 
     According to an aspect the rod-shaped element  31  may be configured to cooperate, in a locked position, with the bottom surface of the insertion groove  32 . 
     The sidewalls of the insertion groove  32  and the locking groove  35  may comprise material of the core of the first panel  10  or the second panel  20 , dependent on in which panel they are made. According to an aspect they may also be enforced with, e.g., metal or glass fibre. 
     According to an aspect the locking groove  35  may be impregnated/reinforced with a liquid. 
     According to an aspect the first panel  10  and the second panel  20  may be assembled by a displacement of the first panel  10  relative the second panel  20  in an assembly direction which is essentially parallel with the first panel surface  13  as shown in  FIGS.  5 A,  11  and  16   . The mechanical locking device is according to an aspect configured to automatically lock the first panel  10  to the second panel  20  when the rod-shaped element  31  is inserted into the insertion groove  32  and the locking part  34  is inserted into the locking groove  35  and locks against the locking surface  37  by said displacement of the first panel  10  relative the second panel  20 . The set may be locked when the first edge surface  11  is arranged against the second panel surface  22 . 
     According to an aspect the first panel  10  may comprise two or more of said first edge surface  11  according to the above. Put in another way, one or more of said rod-shaped elements  31  may be positioned at two or more of the edges of the first panel  10 , as disclosed in  FIGS.  2 - 4 ,  9 ,  11 ,  12  and  16   . 
     According to an aspect the second panel  20  may comprise two or more of said fourth edge surface  25  according to the above. Put in another way, one or more of said insertion grooves  32  may be positioned adjacent two or more of the edges of the second panel  10 , as disclosed in  FIGS.  1 - 4 ,  9 ,  11 ,  12  and  16   . 
     According to an aspect, as shown in  FIG.  11   , two of the first panels  10 , two of the second panels  20 , and one back panel  40  may be assembled. 
     A left embodiment of the of the first panel  10  may be assembled to a bottom embodiment of the second panel  20  by displacing the left embodiment of the first panel  10  relative the bottom embodiment of the second panel  20  in the assembly direction  111 . A right embodiment of the of the first panel  10  may be assembled to the bottom embodiment of the second panel  20  by displacing the right embodiment of the first panel  10  relative the bottom embodiment of the second panel  20  in the assembly direction  112 . An embodiment of the back panel  40  may be assembled to the left and right embodiment of the first panel  10  and the bottom embodiment of the second panel  20  by displacing the embodiment of the back panel  40  in an assembly direction  113  which is essentially perpendicular to the second panel surface  22  of the bottom embodiment of the second panel  20 . A top embodiment of the second panel  20  may be assembled to the left and right embodiment of the first panel  10  and the embodiment of the back panel  40  by displacing the top embodiment of the second panel  20  in the assembly direction  114 . 
     According to an aspect, as shown in  FIG.  16   , two of the first panel  10 , two of the second panel  20 , may be assembled. 
     A left embodiment of the of the first panel  10  may be assembled to a bottom embodiment of the second panel  20  by displacing the left embodiment of the first panel  10  relative the bottom embodiment of the second panel  20  in the assembly direction  111 . A right embodiment of the of the first panel  10  may be assembled to the bottom embodiment of the second panel  20  by displacing the right embodiment of the first panel  10  relative the bottom embodiment of the second panel  20  in the assembly direction  112 . A top embodiment of the second panel  20  may be assembled to the left and right embodiment of the first panel  10  and the embodiment of the back panel  40  by displacing the top embodiment of the second panel  20  in the assembly direction  114 . 
     A length  93  of the back panel  40  which in the locked position may be inserted in the panel groove  12  of the first panel  10  may be essentially the same or greater than a length  94  of the first panel  10  at the second edge surface  14  of the first panel. The length  93  of the back panel  40  may be equal to the length  94  of the first panel  10  plus about half the height H 1  of the panel groove  12  to about two times the height H 1  of the panel groove  12  or equal to the length  94  of the first panel  10  plus the height H 1  of the panel groove  12 .  FIG.  11    shows the length  93  of the back panel  40  which extend between an upper edge  87  of the back panel and a lower edge  88  of the back panel. 
       FIGS.  17 A-D  show enlargements of parts of a set during assembling.  FIG.  17 A  shows an embodiment in a first position in which the back panel  40  is inserted in the panel groove  12  of the first panel  10 . The upper edge  87  of the back panel  40  is below the first edge surface  11  of the first panel.  FIG.  17 C  shows that in this first position the lower edge  88  of the back panel may contact a lower surface  89  of the panel groove  23  of the lower second panel  20 . 
       FIG.  17 B  shows the embodiment in a second position in which, an upper second panel  20  has been displaced  114  and assembled to the first panel  10 , and the back panel  40  has been displaced to a position in which the upper edge  87  of the back panel  40  is within the panel groove  23  of the upper second panel  20 .  FIG.  17 D  shows that in this second position the lower edge  88  of the back panel may be at a distance  91  from the lower surface  89  of the panel groove  23  of the lower second panel  20 . The lower edge  88  of the back panel  40  may be positioned at a distance  91  from the second panel surface  22  of the second panel. The distance may be within the range of about ⅓ to about ⅔ a height H 2  of the panel groove  23  of the second panel, or about half the height H 2  of the panel groove  23  of the second panel. 
     The height H 2  of the panel groove  23  of the lower second panel groove may be greater than the height H 2  of the panel groove  23  of the upper second panel groove. The set may be rotated such that the gravity causes the displacement of the back panel to obtain the position in which the upper edge  87  of the back panel  40  is within the panel groove  23  of the upper second panel  20 . 
     The back panel may be displaced by gravity or by hand and the position in which the upper edge  87  of the back panel  40  is within the panel groove  23  of the upper second panel  20  may be maintained by arranging a positioning element  92  between the panel and the panel groove  12  of the first panel and/or between the back panel and the panel groove  23  of the second panel. 
     Embodiments of the first panel groove  12  may comprise a width W 1  which is essentially the same as a thickness T of the back panel  40 . A part of the first panel groove  12  may be wider which may allow an embodiment of the positioning element  50  to be positioned between the back panel and the first panel groove  12  to maintain the position in which the upper edge  87  of the back panel  40  is within the panel groove  23  of the upper second panel  20 . 
     Embodiments of the second panel groove  24  may comprise a width W 2  which is essentially the same as a thickness T of the back panel  40 . A part of the second panel groove  23  may be wider which may allow an embodiment of the positioning element  50  to be positioned between the back panel  40  and the second panel groove  23  to maintain the position in which the upper edge  87  of the back panel  40  is within the panel groove  23  of the upper second panel  20 . 
     The back panel may be displaceable and the position in which the upper edge  87  of the back panel  40  is within the panel groove  23  of the upper second panel  20  may be maintained by an embodiment of the locking device  4  disclosed in WO2019/125292 or WO2019/125291. The entire contents of WO2019/125292 and WO2019/125291 are hereby incorporated herein by reference in their entirety. 
     The core of the first panel  10  and/or of the second panel  20  may be a wood-based core, such as MDF, HDF, OSB, WPC, plywood or particleboard. The core may also be a plastic core comprising thermosetting plastic or thermoplastic, e.g., vinyl, PVC, PU or PET. The plastic core may comprise fillers. 
     The first panel  10  and/or the second panel  20  may also be of solid wood. 
     The first panel  10  and/or the second panel  20  may be provided with a decorative layer, such as a foil or a veneer, on one or more surfaces. 
     According to an aspect the set of panels are resilient panels. The resilient panels may comprise a core comprising thermoplastic material. The thermoplastic material may be foamed. 
     The thermoplastic material may comprise polyvinyl chloride (PVC), polyester, polypropylene (PP), polyethylene (PE), polystyrene (PS), polyurethane (PU), polyethylene terephthalate (PET), polyacrylate, methacrylate, polycarbonate, polyvinyl butyral, polybutylene terephthalate, or a combination thereof. The core may be formed of several layers. 
     The aspects described above may comprise a decorative layer, such as a decorative foil comprising a thermoplastic material. The thermoplastic material of the decorative layer may be or comprise polyvinyl chloride (PVC), polyester, polypropylene (PP), polyethylene (PE), polystyrene (PS), polyurethane (PU), polyethylene terephthalate (PET), polyacrylate, methacrylate, polycarbonate, polyvinyl butyral, polybutylene terephthalate, or a combination thereof. The decorative foil may be printed, for example by direct printing, rotogravure, or digital printing. According to an aspect the decorative layer comprises melamine, a high pressure laminate (HPL) or a veneer. 
     The aspects described above may comprise a wear layer such as a film or foil. The wear layer may comprise thermoplastic material. The thermoplastic material may be polyvinyl chloride (PVC), polyester, polypropylene (PP), polyethylene (PE), polystyrene (PS), polyurethane (PU), polyethylene terephthalate (PET), polyacrylate, methacrylate, polycarbonate, polyvinyl butyral, polybutylene terephthalate, or a combination thereof. 
     The aspects described above may comprise a wood base core, such as HDF, MDF, plywood, particleboard, OSB or Masonite. 
     The different aspects, embodiments and alternatives described above may be combined with one or more of the other described aspects, embodiments and alternatives. 
     Embodiments 
     1. A set comprising a first panel ( 10 ), a second panel ( 20 ) and a mechanical locking device for locking the first panel ( 10 ) to the second panel ( 20 ), wherein
         the first panel ( 10 ) comprises a first edge surface ( 11 ) and a first panel surface ( 13 ),   the second panel ( 20 ) comprises a second panel surface ( 22 ),   the first edge surface ( 11 ) is facing or parallel to the second panel surface ( 22 ) in a locked position of the first and the second panel ( 10 ,  20 ),   the mechanical locking device comprises at least one rod-shaped element ( 31 ) at the first edge surface ( 11 ) and at least one insertion groove ( 32 ) at the second panel surface ( 22 ),   the rod-shaped element ( 31 ) is configured to cooperate with the insertion groove ( 32 ) in the locked position,   the rod-shaped element ( 31 ) extends at a first angle (α 1 ) from the first edge surface ( 11 ),   the insertion groove ( 32 ) extends into the second panel surface ( 22 ) at a second angle (α 2 ) from the second panel surface ( 22 ),   the mechanical locking device further comprises a locking groove ( 35 ) at the second panel surface ( 22 ) and a locking part ( 34 ) at the first edge surface ( 11 ) or a locking groove ( 35 ) at the first edge surface ( 11 ) and a locking part ( 34 ) at the second panel surface ( 22 ),   the locking groove ( 35 ) comprises at least one locking surface ( 37 ) extending at a third angle (β) from the first edge surface ( 11 ) or from the second panel surface ( 22 ),   the locking part ( 34 ) is configured to cooperate with the locking groove ( 35 ) and lock against the locking surface ( 37 ) in the locked position,   the third angle (β) is different than the first angle (α 1 ),   the first angle (α 1 ) is within the range of about 30° to 60°, or within the range of about 40° to about 50, or about 45, and   the mechanical locking device is configured to obtain the locked position by displacing first panel ( 10 ) relative the second panel ( 20 ) in an assembly direction which is essentially parallel with the first panel surface ( 13 ).       

     2. The set as in embodiment 1, wherein the assembly direction ( 111 ,  112 ,  114 ) is essentially parallel with at least one of the first angle (α 1 ) and the second angle (α 2 ). 
     3. The set as claimed in embodiment 1 or 2, wherein the third angle (β) is about 45° to about 90° larger than the first angle (α 1 ). 
     4. The set as in any one of the preceding embodiments, wherein the third angle (β) of the locking surface ( 37 ) is in the range of about 70° to 110°, or within the range of about 80° to 100%, or within the range of about 85° to 95°, or about 90°. 
     5. The set as in any one of the preceding embodiments, wherein the locking part ( 34 ) is flexible. 
     6. The set as in any one of the preceding embodiments, wherein the locking part ( 34 ), in an unflexed/non-compressed state, is configured to be positioned partly in the locking groove ( 35 ). 
     7. The set as in any one of the preceding embodiments, wherein the locking part ( 34 ) comprises a spring. 
     8. The set as in any one of the preceding embodiments, wherein the locking part ( 34 ) is arranged in a locking part groove ( 38 ) on the first edge surface ( 11 ) or at the second panel surface ( 22 ). 
     9. The set as in claim  8 , wherein the locking part ( 34 ), in a flexed/compressed state, is configured to be substantially positioned in the locking part groove ( 38 ). 
     10. The set as in any one of the preceding embodiments, wherein at least one of the insertion groove ( 32 ) and the locking groove ( 35 ) is a drill hole. 
     11. The set as in claim  10 , wherein the drill hole is a bottom-ended drill hole. 
     12. The set as in any one of the preceding embodiments, wherein the rod-shaped element ( 31 ) is arranged in a rod element groove ( 36 ) in the first edge surface ( 11 ). 
     13. The set as in any one of the preceding embodiments, wherein set comprises a first panel groove ( 12 ) on the first panel surface ( 13 ) of the first panel ( 10 ), and a second panel groove ( 23 ) on the second panel surface ( 22 ) of the second panel ( 20 ). 
     14. The set as in claim  13 , wherein a width (W 1 ) of the first panel groove ( 12 ) is essentially the same as the width (W 2 ) of the second panel groove ( 23 ). 
     15. The set as in any of embodiments 13 to 14, wherein the set further comprises a back panel ( 40 ) configured to be inserted in, and optionally to cooperate with, the first and second panel groove ( 12 ,  23 ). 
     16. The set as in any of embodiments 13 to 15, wherein the first panel ( 10 ) comprises a second edge surface ( 14 ), the second panel ( 20 ) comprises a third edge surface ( 24 ), the first panel groove ( 12 ) is substantially parallel to the second edge surface ( 14 ) and the second panel groove ( 23 ) is substantially parallel to the third edge surface ( 24 ). 
     17. The set as in any of embodiments 13 to 16, wherein the first panel groove ( 12 ) extends substantially along the entire second edge surface ( 14 ) and the second panel groove ( 23 ) extends essentially along the entire third edge surface ( 24 ). 
     18. The set as in any of embodiments 13 to 17, wherein at least one of the first panel groove ( 12 ) and the second panel groove ( 23 ) is bottom-ended. 
     19. The set as in any of embodiments 16 to 18, wherein an extension (H) of the back panel ( 40 ) from the first edge ( 11 ) of the first panel ( 10 ), when one first panel, one second panel and one back panel have been assembled, is less than an extension of the rod shaped element ( 31 ) from the first edge surface ( 11 ) of the first panel ( 10 ).