Method for embroidering three-dimensional workpieces

A method for embroidering three-dimensional workpieces (2) uses an embroidery machine (100) with at least one embroidery head (101) for embroidering and at least one embroidery frame (1) for positioning the workpiece (2). The workpiece (2) is moved by means of the embroidery frame (1) by at least two angles (Θ, μ, ω) in relation to at least two axes (X, Y, Z), which are in relation to the movement axis of the embroidery head (101) positioned to introduce at least one stitch of embroidery into the workpiece (2).

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of German Patent Application DE 10 2023 103 349.2, filed on Feb. 13, 2023, which is incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a method for embroidering three-dimensional workpieces.

BACKGROUND

Embroidery machines that can embroider not only flat structures, but also curved structures, are generally known. Such curved structures are often half-round and are used as headgear in the form of caps.

Sewing robots that can process curved surfaces are also known. Post bed sewing machines used to sew hollow objects are also generally known.

The full-surface embroidery of a curved three-dimensional structure using an inexpensive articulation mechanism is currently not possible with an embroidery machine. Instead, for example, in the case of a cap, only a partial area can be embroidered. Such a partial area corresponds to a rectangular section of a cylinder surface. The movement for embroidering such a section of a cylinder surface with respect to the needle is derived from an X and Y direction of an embroidery frame that is only partially present. This is done in such a way that the movement in the depth direction Y of the pantograph of the embroidery machine is maintained. In contrast, the lateral movement X of the pantograph is converted into a rotary movement, for example by means of a cable pull. This makes it possible to embroider a portion of a cap, with this portion being determined by the way the cap is clamped before the embroidery process. The design to be embroidered on this section is provided to the embroidery machine control in the form of stitch data. This stitch data is a sequence of data in the form of a triple consisting of an adjustment path in the X direction, an adjustment path in the Y direction and the information to create a stitch at the position reached after the adjustment of the cap to be embroidered. A large number of these triples in an orderly sequence one after the other create the desired design on the cap. Since the section to be embroidered is part of a cylinder surface, its development can be viewed as a flat rectangular element. Therefore, to generate the stitch data triples, a design is simply artistically created in a rectangular base area, since the transfer to the section of the cylinder surface is inherent through the use of the previously mentioned cable pull mechanism.

If several partial surfaces of such a cap are to be embroidered, this is only possible by laboriously re-clamping the cap so that several cylindrical sections can be embroidered one after the other.

SUMMARY

The present disclosure eliminates the aforementioned disadvantages. Embroidering a curved workpiece is no longer restricted to a rectangular section of a cylinder surface. Rather, an almost full-surface embroidery of the surface of a workpiece can be advantageously achieved. The term workpiece is used in the further description to reflect that the disclosed method and apparatus are not limited to the embroidery of caps, but can be used with a broad range of objects.

The method for embroidering three-dimensional workpieces is carried out using an embroidery machine which comprises at least one embroidery head for embroidering and at least one embroidery frame for positioning the workpiece.

The workpiece is positioned by pivoting the embroidery frame about at least two angles with respect to at least two axes which are non-parallel to the axis of movement of the embroidery head, in order to introduce at least one stitch of embroidery into the workpiece. The at least two axes preferably include a lateral axis and a longitudinal axis, with the embroidery head moving in a vertical axis. The lateral axis preferably intersects the vertical axis. The longitudinal axis preferably intersects the vertical axis. The lateral axis, the longitudinal axis, and the vertical axis may intersect in a point of origin.

This design enables the embroidery of a workpiece, for example a cap, in one clamping over almost the entire surface of the workpiece. The embroidery frame includes or is operatively connected to drives that enable the pivoting motion. The workpiece can preferably be rotated about the vertical axis.

DETAILED DESCRIPTION

FIGS.1-7show an embroidery frame1for positioning a workpiece2. The workpiece2is clamped to the embroidery frame1. The embroidery frame1includes or is operatively connected to at least one drive3,4,5for the driven pivoting or rotating of the workpiece2by at least two angles Θ, μ, ω.

An embroidery machine100for embroidering the workpiece comprises at least one embroidery head101for embroidering and at least one embroidery frame1for positioning the workpiece2.

In a particularly advantageous embodiment, the embroidery machine100can also include several embroidery frames1, with each of these several embroidery frames1being assigned at least one embroidery head101.

The embroidery machine100is provided with an articulation mechanism for the curved three-dimensional workpiece2, which allows the curved workpiece2to be tilted about the two independent but limited angles Θ and μ and rotated about the infinite angle of rotation ω. This arrangement makes it possible to bring almost any position of the surface of the curved workpiece2below the needle position.

FIG.1shows a post bed embroidery machine100with a control. The post bed embroidery machine100is equipped with an embroidery head101which is equipped with several needles, with only one of the several needles within the embroidery head101being connected to a drive mechanism of the embroidery head at a time. By moving the embroidery head101laterally, it is possible to select another one of the several needles, so that the selected needle is driven by the drive mechanism of the embroidery head101. Since the different needles can be equipped with different colored threads, for example, it is possible to create embroidered areas of different colors in order to achieve the artistic impression of the embroidery.

FIG.3shows the embroidery frame1for full-surface embroidery as well as several drives3,4,5of the embroidery frame1.

InFIG.2, the embroidery frame1for full-surface embroidering and the drives3,4,5of the embroidery frame1are shown in detail in relation to the embroidery head101. For orientation purposes, the Cartesian axes X, Y and Z are shown. Here, the pitch angle Θ denotes a rotation about the longitudinal X-axis, the roll angle μ denotes a rotation about the lateral Y-axis and the yaw angle ω denotes a rotation about the vertical Z-axis. The pitch angle Θ and roll angle μ can have both positive and negative values, but are limited due to the mechanical arrangement. For example, Θ and μ may each be limited to a pivot angle in the range between −45° and +45°. The yaw angle ω can also assume positive and negative values and is not inherently limited by the mechanical arrangement.

FIG.3shows the embroidery frame1for full-surface embroidering in relation to at least one post102. The post102accommodates a bobbin and bobbin case, which holds a bottom thread. The embroidery frame1is preferably gimballed within the post102. The gimbal suspension allows the pivoting shown inFIG.2by the pitch angle Θ about the longitudinal X-axis and by the roll angle μ about the lateral Y-axis as previously described. To carry out the pivoting around the X-axis, a pitch drive3is used to adjust the pitch angle Θ. Executing a positive adjustment of the pitch drive3results in the front area of the embroidery frame1pivoting up by the positive pitch angle Θ and the rear area of the embroidery frame1pivoting downwards to the same extent. Accordingly, the pivoting directions behave in reverse when the drive3is adjusted negatively.

Independently thereof, a roll drive4is used to adjust the roll angle μ around the lateral Y-axis. Executing a positive adjustment of the drive4results in the right area of the embroidery frame1pivoting up by the positive roll angle μ and the left area of the embroidery frame1pivoting downwards to the same extent. Accordingly, the pivoting directions behave in reverse when the drive4is adjusted negatively.

Since the pitch drive3for the pitch angle Θ and the roll drive4for the roll angle μ are advantageously orthogonal to one another, it is possible to bring the entire surface of the clamped workpiece2under the needle positions for carrying out embroidery. The orthogonal arrangement of the drives3,4to one another is one of several possible embodiments.

FIG.3shows further elements of the embroidery frame1according to the invention for full-surface embroidery. A longitudinal strut8connects the fixed inner ring7along the longitudinal X-axis with the gimbal suspension within the post102. Accordingly, a lateral strut9connects the fixed inner ring7along the Y-axis with the gimbal suspension within the post102.

A rotatable outer holder6serves to receive the workpiece2—as shown inFIG.4—during embroidering and to hold it at the lower edge. The rotatable outer holder6is mounted on the fixed inner ring7in such a way that rotation of the outer holder6around the inner fixed ring7by the yaw angle ω is possible. This can be achieved, for example, by incorporating a circumferential groove on the inside of the outer holder6and attaching webs which engage in the circumferential groove of the holder6on the outside of the fixed ring7. A yaw drive5is used to realize the rotation of the outer holder6by the yaw angle ω around the Z axis. Drive energy of the yaw drive5can be transmitted to the outer holder6, for example, by incorporating a gear ring all around the inside of the outer holder6and a driven gear wheel from the yaw drive5engaging in this gear ring and thus transmitting the rotational movement. This arrangement allows continuous, unrestricted rotation of the workpiece2about the vertical Z-axis. The yaw angle of rotation ω can assume any positive or negative values.

By implementing three independent angle adjustments for pitch Θ, roll μ, and yaw ω, the embroidery of the workpiece is advantageously possible in one clamping and over almost the entire surface of the workpiece2as well as all around.

FIGS.5,6and7each show different positions of the workpiece2in relation to the needle position. This makes it possible to embroider almost the entire surface of a three-dimensional workpiece2using the articulation mechanism described here.

According to the method, the respective new position of the workpiece2is particularly advantageously determined from predetermined coordinate triplets and the at least one embroidery frame1is controlled by means of the drives3,4,5in such a way that the positioning of the workpiece2is carried out around the pitch angle Θ, the roll angle μ, and the yaw angle ω.

In addition, it can be advantageous for the positioning of the workpiece2around the pitch angle Θ, the roll angle μ, and the yaw angle ω to be calculated and carried out step by step from continuously transferred coordinates for each stitch of the embroidery.

The articulation mechanism is preferably controlled by the drives (drive units)3,4and5. These can be powered by an electric motor or any other drive energy.

To control the correct movement of the drives3,4,5, a control is preferably provided which determines the new position of the workpiece2from predetermined coordinate triples and sets it using the drives3,4,5. By synchronizing the positioning of the workpiece2with the drive mechanism of the embroidery head101, it is achieved that the needle only penetrates into the workpiece2after it has been positioned and then carries out a stitch of embroidery. By continuously adjusting the workpiece2and introducing further stitches based on the evaluation of the successive coordinate triples, the entire surface of the workpiece2is embroidered.

LIST OF REFERENCE NUMBERS

1Embroidery frame for full-surface embroidering with drives2Workpiece (cap)3Pitch drive for pitch angle adjustment Θ4Roll drive for roll angle adjustment μ5Yaw drive for yaw angle adjustment ω6Rotatable outer ring to receive the workpiece7Fixed inner ring8Longitudinal strut in X-direction9Lateral strut in Y-direction100Post bed embroidery machine with control101Embroidery head102Post for holding the bobbin