angular2 uploading file to PHP, $_FILES is empty - php

Question

I am trying to upload files using angular2 and PHP server. The variable $_FILES is empty and I cannot figure out the reason.
Component code:
let formData:FormData = new FormData();
for (let i = 0; i < this.filmsFiles.length; i++) {
formData.append('images', this.filmsFiles[i], this.filmsFiles[i].name);
}
this.filmDataService.uploadFiles(formData).subscribe( outPutData => {
if(outPutData[0]){...
Service Angular code:
uploadFiles(formData:FormData): Observable {
this.data = 'action=10060&jsonData=""';
let headers = new Headers();
headers.append('Content-Type', 'multipart/form-data; charset=utf-8; boundary=' + Math.random().toString().substr(2));
headers.append('Accept', 'application/json');
let options = new RequestOptions({ headers: headers });
return this.http.post(this.url+'?'+this.data, formData, options)
.map((response:Response) => response.json())
.catch(this.handleError)
}
PHP code:
foreach($_FILES['images']['error'] as $key => $error){
if($error == UPLOAD_ERR_OK){
$name = $_FILES['images']['name'][$key];
$fileNameParts = explode(".", $name);
$nameWithoutExtension = $fileNameParts[0];
$extension = end($fileNameParts);
$newFileName = "film_".$i.time().".".$extension;
move_uploaded_file($_FILES['images']['tmp_name'][$key], '../../images/' . $newFileName);
$newFileNames[]='images/filmsImages/'.$newFileName;
$i++;
}
I've been checking whether the variable this.filmsFiles is empty or not and it contains the files to upload, in the view, file tag, I have:
(change)="filmsFiles[i]=$event.target.files[0]"
The server receives the parameters I send but nothing in $_FILES.
Could you help me please?
Thanks,
Roberto